October
Chemistry World Podcast - October 2009
00.11- Introduction
02.02 -Sniffing out the chemical profile of death
04.42 - Are antioxidants always good for you?
07.53 - James Galloway on concerns that humans are upsetting the nitrogen cycle
14.55 - Is nitrous oxide now the biggest threat to the ozone layer?
17.45 - Plugging in to paper batteries
20.22 - Grab the garlic - Jeya Henry shares his tips on the top three health-giving spices
27.09 - The new bond found to hold collagen together
30.20 - Making MOFs more active
32.50 - The chemical conundrum - what did L-cysteine, used in bread making, used to be made from?
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
(00.11 - Introduction)
Interviewer - Meera Senthilingam
Welcome to the October edition of the Chemistry World Podcast with James Mitchell Crow, Phillip Broadwith, Bibiana Campos-Seijo, and Tom Bond. I'm Meera Senthilingam from thenakedscientists dot com. In this month's show, we explore some deadly scents.
Interviewee - Bibiana Campos-Seijo
They want to create a chemical profile for this, so that they can ultimately design a device that can be carried to the pesticides to discover bodies and then identify how long they have been dead for.
Interviewer - Meera Senthilingam
Sniffing out the crime scene. Bibi Campos-Seijo will be explaining how researchers have identified the scents of death as well as how this will make crime scene investigations more efficient. Also on the way, it may give you smelly breath, but garlic is the godfather of the spices.
Interviewee - Jeya Henry
Garlic contains a group of thiocyanates and it turns out that it has got multifaceted attributes. It certainly is also antibacteriocide, reduces the cholesterol, improves your digestion, the anti-cancer agent, the lists are infinite in terms of its potential.
Interviewer - Meera Senthilingam
Jeya Henry will be revealing the health benefits of his top three spices as well as garlic, shortly. We've also got a new greener design for batteries.
Interviewee - James Mitchell Crow
Well, these are metal-free rechargeable batteries and as you say they are made largely from paper and the advantage that they have over current batteries is that they can be made extremely thin and they can also be made flexible.
Interviewer - Meera Senthilingam
James Mitchell Crow will be explaining just how this paper-thin battery will work later in the show. That's all coming up on this month's Chemistry World Podcast.
(Promo)
The Chemistry World Podcast is brought to you by the Royal Society of Chemistry. Look us up online at chemistryworld dot org.
(End Promo)
(02.02 -Sniffing out the chemical profile of death)
Interviewer - Meera Senthilingam
Now first this month, we imagine going out to a crime scene. A body has been found, but no one knows how long it's been there. Currently it's difficult to work this out, whilst out on location, but now it may be slightly easier. Thanks to a new device that could sniff out the different stages of decomposition. Does this really work, Bibi?
Interviewee - Bibiana Campos-Seijo
Yes, it happens that dogs that are searching for human remains in disaster sites might be soon out of a job because a couple of researchers at Pennsylvania State University are trying to identify the chemical composition of death. They basically have used pigs because pigs replicate the five stages of decomposition of bodies that the humans go through. Basically, they euthanized the pigs and then they tried to collect the volatile organic compounds that are released during the early stages of decomposition. They want to create a chemical profile for death, so that they can ultimately design a device that can be carried to the pesticides or whatever and then help to discover bodies and then identify how long they have been dead for.
Interviewer - Meera Senthilingam
So, what materials where they using to collect the volatile organic compounds?
Interviewee - Bibiana Campos-Seijo
They are using solid-phase microextraction fibres. They have three different types of fibres with polymer coatings on the outside and these are placed over the carcass of the pig within a wooden enclosure that allows airflow I should say that and then these fibres, they are taken regularly back to the lab on ice to avoid the loss of any volatile compounds and then the analysis it directly to a GC-MS apparatus and they have so far worked on the first two weeks from the death of the pig and they have created quick chemical profiles and using these three different types of fibres, they have demonstrated that the chemical profile is virtually identical and is quite accurate in that they see, you know, the same chemicals appear in every time within the same concentration. Other techniques are a lot more complicated, in that they require different type of equipment that needs to have vacuum or some sort of pumping system to draw the air through the collection material. They are going for some, sort of a crime scene investigation sort of device that they can carry and do the analysis in-situ. So hopefully should all be pretty straightforward and ready soon.
(04.42 - Are antioxidants always good for you?)
Interviewer - Meera Senthilingam
And well from rotting flesh now over to cancerous cells, Phil. As it seems antioxidants aren't quite as beneficial as we all think.
Interviewee - Phillip Broadwith
Well, yes. There's a lot of discussion about whether antioxidants prevent cancer or perhaps may be at certain stages aren't so useful and what Joan Brugge of Harvard has been looking at is the very early stages of cancer. Now normal cells have to be attached to a sort of scaffolding matrix that provides them with certain nutrients as signalling compounds and as cancer cells divide very quickly, they soon run out of room to be attached to the matrix. So if you think of a cancer tumour, those cells in the middle of that aren't going to be attached to that matrix, so they need to develop a way of surviving away from that.
Interviewer - Meera Senthilingam
The fact that they do this, has the body come up with various ways to attack them and kill them.
Interviewee - Phillip Broadwith
Yes. Well, there are two different major defence mechanisms. They first is programmed cell death or apoptosis, but a lot of cancers has evolved ways of turning that process off and the second process is that reactive oxygen species which are very oxidizing and help to break down lots of the proteins and molecules in the cell, which cause it to die.
Interviewer - Meera Senthilingam
So how do the cancerous cells then overcome these natural defence mechanisms?
Interviewee - Phillip Broadwith
Well, there are two problems. The first is this genetic apoptosis, which they quite happily turned off using various genes. The second is getting energy, one of the main things that being attached to the matrix is it allow them to transport glucose as a source of energy into the cells. If you are not attached to the matrix, that glucose transport mechanism is turned off. So they either need to find another way of getting glucose, which can be done using various genes or they need to find a different source of energy and that different source of energy could be the oxidation of fatty acids.
Interviewer - Meera Senthilingam
So how would they obtain this energy from fatty acids?
Interviewee - Phillip Broadwith
That's where the antioxidants come in. There is a problem with fatty acid oxidation in these cells that have been detached. When the cells are detached, they start producing reactive oxygen species as the secondary defence mechanism to try and kill the cell. That also blocks fatty acid oxidation. If you then add antioxidants into that, you can neutralize the reactive oxygen species and allow the cell to get its energy from fatty acid oxidation.
Interviewer - Meera Senthilingam
So, basically the presence of antioxidants at this early stage of tumour formation is allowing the cells to proliferate because it's allowing them to get energy from the fatty acid metabolism.
Interviewee - Phillip Broadwith
Yes. That's exactly right.
Interviewer - Meera Senthilingam
So now knowing this, what can be done to understand more about tumour formation and hopefully prevent tumour spread?
Interviewee - Phillip Broadwith
It's crucial that we understand how the metabolism and chemistry that's going on within cancer cells changes through their lifetime. We know that established cancer cells don't use fatty acids as a form of energy because they spend a lot of energy making fatty acids, fatty acids accumulating cancer cells. But it seems that in this very early stage, just when the cells detach from the scaffolding around them that they are using this as a sort of interim source of energy. Understanding that will hopefully help us understand where we can intervene in that process and stop the cancer from spreading.
Interviewer - Meera Senthilingam
So understanding this use of antioxidants in the early stages of cancer cell proliferation could help stop the cancer in its tracks. Thanks Phil.
(07.53 - James Galloway on concerns that humans are upsetting the nitrogen cycle)
Interviewer - Meera Senthilingam
Now the pollution of our environment and the warming of our planet have been issues that we have been aware of and trying to deal with for a long time now and the main culprit we all seem to be worrying about is carbon dioxide or CO2, but there's another element that has been causing damage, whilst in the shadows of CO2and that's nitrogen. James Galloway from the University of Virginia has been trying to bring the trouble nitrogen is causing out into the light, to show that this too is a major environmental concern.
Interviewee - James Galloway
The current concern regarding nitrogen is that there is too much in the environment. As a background, let me say that nitrogen is very common in the environment, but it's in a form that is not reactive, it's in the form of the molecule N2, two nitrogen elements put together and that is not biologically reactive mostly, chemically or physically reactive. However, when that N2is converted to other forms of nitrogen, they become biologically, chemically and physically active. This is a good thing in some sense because all living systems need nitrogen, but because humans are creating these forms of reactive nitrogen at a much faster rate than nature, reactive nitrogen is accumulating in the environment, where it contributes to many, if not most of the environmental impacts that humans and ecosystems are experiencing today.
Interviewer - Meera Senthilingam
So how does nature create nitrogen in the first place?
Interviewee - James Galloway
Natural systems create reactive nitrogen that is converting inert into any other form of nitrogen, which we term reactive nitrogen by two main processes; the dominant one is biological nitrogen fixation where microorganisms actually within the cells convert N2into reactive nitrogen. Another important one in some regions is lightening, when lightening occurs, lots of energy is released and the molecule N2in the atmosphere reacts with oxygen to form nitric oxide. So that's how nature creates reactive nitrogen and nature also converts reactive nitrogen back to N2in the process of denitrification, so you don't have reactive nitrogen accumulating in the environment. But now humans have come along and by three main mechanisms, they also create reactive nitrogen. First they plant legumes, we think soybeans and peanuts, and by virtue of planting those, these are plants that act as a host for those same bacteria and microorganisms that create reactive nitrogen through biological nitrogen fixation, so they are enhancing nature's ability to create reactive nitrogen. The second one and by far the largest on a global basis, is making of nitrogen fertilizer by the Haber-Bosch process, where under high temperatures and pressures, the molecule N2and the molecule H2- hydrogen are reacted to form ammonia. Then the third one is combustion of fossil fuels and you convert N2in the atmosphere with oxygen over to nitric oxide.
Interviewer - Meera Senthilingam
Something that you have come up with, to describe and explain the real kind of problem that nitrogen is having is with your nitrogen cascade. What is this and how does this show the effects of nitrogen and how it's amplified?
Interviewee -James Galloway
The nitrogen cascade is that one atom of nitrogen, one atom of reactive nitrogen created by humans can cascade through the environmental systems, contributing in turn to each of those impacts and so imagine a molecule of nitric acid, a molecule of nitric oxide that is emitted from a car's tailpipe that is emitted into the atmosphere, where it can cause ozone concentrations increase, which contribute to smog, that molecule of nitrogen, that atom of nitrogen can be converted into a particle which can contribute to haze, then that atom of nitrogen can be taken out of the atmosphere by rain and snow, acidifying the rain and snow in the process, which will then acidify soils and streams and lakes and then as this same atom of nitrogen moves through the environmental system is transported in rivers to coastal environment, where it acts as an over enriching nutrient and can cause oxygen loss in coastal environments leading to dead zones and then again the same atom of nitrogen can be converted to a gas called nitrous oxide which is two atoms of nitrogen and one atom of oxygen which would be emitted in the atmosphere as a greenhouse gas, so it contributes to global climate change and then this same atom of nitrogen again in the form of nitrous oxide can diffuse into the stratosphere contributing to stratospheric ozone depletion. And so just this one creation of reactive nitrogen in the form of nitric oxide cascades through all the environmental systems.
Interviewer - Meera Senthilingam
So what are the proposed solutions, how can we achieve this balance?
Interviewee - James Galloway
The most obvious is since when reactive nitrogen is formed during combustion of fossil fuels that's formed by accident, we don't need that reactive nitrogen. And so we have the technology, we know the science, we have the public policy instruments and in some countries there are laws to decrease the amount of reactive nitrogen emitted to the atmosphere from fossil fuel combustion, so that's simple to do technically. Another way on the food production system is, we can make crops more efficient in taking up reactive nitrogen. Currently, of all the reactive nitrogen in the form nitrogen fertilizer put on crop plants, only about 30 to 50% is taken up by the crop, the rest is lost to the environment. The same can be said about animals, the world consumes a lot of meat, animals need nitrogen just like crops, just like people, so we could make this feeding of animals more efficient, we can have a better mixture of amino acids in the animal feed, so that more of the nitrogen that enters the animal's mouth, stays with the animal, instead of coming out the other end.
Interviewer - Meera Senthilingam
So those are some possible solutions to ease the problem, but as individuals we can play our part too by eating less meat and reducing our fossil fuel consumption. That was James Galloway from the University of Virginia, explaining how the increasing levels of reactive nitrogen in our atmosphere is damaging our environment.
(Promo)
(End Promo)
Interviewer - Meera Senthilingam
You are listening to the Chemistry World Podcast with me Meera Senthilingam. And still to come, we discover the benefits of spicing up your life, reveal a new, greener form of battery and discover a new chemical bond that could not only help treat Goodpasture's syndrome, but also give us an insight into the entire animal kingdom.
(14.55 - Is nitrous oxide now the biggest threat to the ozone layer?)
Interviewer - Meera Senthilingam
But first keeping on the topic of nitrogen, Tom, you found out about another way this element is affecting our atmosphere.
Interviewee -Tom Bond
Yeah that's right. This is a study that has been undertaken by A. R. Ravishankara and his colleagues who are from NOAA, which is the National Oceanic and Atmospheric Administration Research Center, and they are at Colorado in the USA. They've published a study in science, the main point being that nitrous oxide which is N2O is now thought to be the main contributory factor to the depletion of the ozone layer and it will remain in that status for the rest of this century.
Interviewer - Meera Senthilingam
Why is nitrous oxide now the concern and how has it kind of overtaken other potential worries about chemicals that affect the ozone?
Interviewee -Tom Bond
It basically seemed that it's been over looked in the past to some extent and that's because most of the focus has been on the CFCs and also HCFCs. CFCs are chlorofluorocarbons and the HCFCs are the hydrochloroflurocarbons. It was really in the later years of the last century, the 1980s where pictures of the ozone layer showed that there was a big hole there and this kind of raised the issue in the public consciousness and then as a result of that the Montreal Protocol was formulated in 1987. So this banned use of the CFCs which at the time were the most destructive chemicals depleting the ozone layer. The HCFCs were then introduced as temporary replacements for the CFCs. They are also harmful towards the ozone layer, but not as much as the CFCs, but that really is why no one has looked particularly at nitrous oxide. This group has run a computational simulation model which shows that now N2O is the main chemical depleting the ozone layer.
Interviewer - Meera Senthilingam
How is this nitrous oxide created by human activity and what effect does it actually have on our ozone, why does it damage our Ozone?
Interviewee - Tom Bond
They are both natural and manmade sources and I think actually natural sources are still more important than manmade nitrous oxide. So, depends on which information source you look at, but roughly 30% of the nitrous oxide, which ends up in the stratosphere comes from manmade sources. Of this the largest single source is nitrate fertilizers used for agriculture and then it ends up as nitrogen oxides in the atmosphere and then these nitrogen oxides react with ozone thus depleting it.
Interviewer - Meera Senthilingam
Just how big a problem is nitrous oxide? So what levels are we looking at here, in our atmosphere?
Interviewee - Tom Bond
What they've done, they have calculated something called the ODP which is the ozone depleting potential. Nitrous oxide has a similar ODP to some of the HCFCs.
(17.45 - Plugging in to paper batteries)
Interviewer - Meera Senthilingam
Okay, so everyone needs to do their bit to help the environment as well and one way we could do this in the future is by using paper batteries. So, what are these about, James?
Interviewee - James Mitchell Crow
Well, these are metal-free rechargeable batteries and as you say they are made largely from paper and the advantage that they have over current batteries is that they can be made extremely thin and they can also be made flexible, so you could even consider rolling them up to increase the density of the power that they can hold. This is some research that's come out of Uppsala University in Sweden and has basically two research groups that were working on quite different standing things. One group were looking at conducting organic polymers, so these are long chain organic molecules, which have lots of double bonds in so they can conduct electrons along the backbone of the molecule and the other group were looking at cellulose produced by a particular kind of algae and this cellulose has acquired unique nano structure has an extremely high surface area, extremely rough surface on the nanoscale. So what these groups have done is get together and basically coat the cellulose with this conducing polymer and they found that makes a really effective electrode. That's what they have done a little while ago. What they've done now is put two of those electrodes together, separated by a sheet of filter paper that has just been soaked in some salty water and discovered that that works as quite an effective battery.
Interviewer - Meera Senthilingam
Although it may work as a battery, just what kind of figures are we looking at into the actual voltage and the power that these batteries create?
Interviewee - James Mitchell Crow
In terms of the capacity, it's quite a lot lower than the lithium ion batteries that we all have in our laptops and mobile phones these days. I think they've done a thousand cycles of charging and discharging and shown that they do have quite a long life. They work in quite a similar way to lithium ion batteries, but it's the chloride ions from the salty water that actually transfers from one electrode to the other, so they flow in one direction when it's discharging and then sort of pump back the other way, when the batteries are being charged up.
Interviewer - Meera Senthilingam
So due to this flexibility and their thinness what are the potential uses then of these batteries?
Interviewee - James Mitchell Crow
Well, they are also quite lightweight as well as you can imagine incorporating them into clothing to power all sorts of devices, the authors are even suggesting they could be impregnated into wallpaper to power, I don't know, goodness knows what, your wall clock or something and they've also talked about putting them into packaging, powering active displays on things like medicines, for example, could be quite beneficial.
Interviewer - Meera Senthilingam
So we could soon see models with lights flashing all down them as they walk down the catwalk and have light designs covering our walls. Thanks James.
(20.22 - Grab the garlic - Jeya Henry shares his tips on the top three health-giving spices)
Interviewer - Meera Senthilingam
Now spices such as garlic, cinnamon, chilly own acquired taste. There are some of us that put them in everything we cook or boast about how much of things like chilly we can handle in our food and there are others that just can't stand them. But nutritionists have been studying these spices for many years now and have found a variety of benefits of these spices on our health. One such scientist is Jeya Henry from Oxford Brookes University and he has identified his top three spices in terms of their health benefits. So I spoke to him to find out what these spices are and at number three we have cinnamon.
Interviewee - Jeya Henry
Well, it turns out that cinnamon in recent years has been shown repeatedly from different laboratories that it has a very unique property of modulating your blood glucose and in other words many people around the world are diabetic, which is as you know a way in which your blood glucose levels are not very well controlled, so you have what is called hyperglycaemia and the common intervention is to either provide insulin or some tablets that cause you to reduce your blood glucose. Now it is quite challenging that people have noticed from the time of the Vedic period which goes back as you know millennia, that cinnamon has an effect on what they call at that time, sugar problems, and I think they were quite clever in articulating that, but recent studies both from America and from Europe have shown that yes, providing cinnamon as a powder form in food appears to have a moderating effect on your blood glucose and I think that's a very exciting observation.
Interviewer - Meera Senthilingam
Now what is the actual compound in the cinnamon that has this effect on the body and how does it work?
Interviewee - Jeya Henry
Well, I think those two questions have still not been resolved, I think the analytical chemistry is still up on speed, but also we do not know whether it actually stimulates insulin production, which is what the speculation has been, as you know, there are compounds that are available in the market, pharmacological, that stimulate insulin production by the pancreas. So therefore it could well be that we are now on a starting of a journey, so at the moment, it's what I would call an observational study, so the next stage will be the analytical chemistry to identify the particular compound.
Interviewer - Meera Senthilingam
Now then moving up your ranks to number two is turmeric. So what is it about turmeric that's beneficial to the human body?
Interviewee - Jeya Henry
Well, turmeric has been used for centuries, certainly in India, as an excellent antimicrobial and a kind of antiseptic and in India, especially, young women who have just had a bath, they normally have their face garnished with turmeric because it actually gets rid of your pimples and the acne and all the microbes that are surrounding it. But the more recent exciting observation is that it may have an effect on reducing the amyloid formation in your brain cells, so that it reduces your risk of becoming demented. One form of dementia in Alzheimer's is due to amyloid formation of the proteins in your brain and it turns out that turmeric has some way in which it actually mechanistically stops that amyloid formation, reduces your risk of gaining dementia, which today has been labelled as a major public health issue around the world.
Interviewer - Meera Senthilingam
So what is the compound within this turmeric that's having this dual effect then?
Interviewee - Jeya Henry
The compound that has been identified is called curcumin, which is also a very powerful antioxidant and as we speak there is also clinical trial using it as a therapeutic intervention for anticancer agents. So it is quite a fascinating compound in terms of these multiple attributes due to health and well-being.
Interviewer - Meera Senthilingam
Now the spice at the top of your list, having benefits for the human body is a particular spice, I myself love, and that's garlic, which you've been quoted to say that if you could only eat one spice in every food that you eat and nothing else, it would be garlic. So why is garlic so great that it has the best benefits above everything else?
Interviewee - Jeya Henry
Garlic contains a group of thiocyanates and it turns out that it has got even more than turmeric, a kind of a multifaceted attributes. It certainly is also antibacteriocide, reduces the cholesterol, improves your digestion, we also know that it has got very unusual properties as anticancer agent, the lists are infinite in terms of its potential, but I think these four are quite important, in that these are issues that surround many of us in terms of our day-to-day lives and so therefore it has got in one single package as it were, these various attributes that are going to improve the quality of your life.
Interviewer - Meera Senthilingam
So, I mean, there are a variety of foods now that have been found to be very beneficial. So to what degree should someone spice up their life then, as opposed to incorporating all these other good foods.
Interviewee - Jeya Henry
Well, I think spicing up life will be like turbo-charging your engine, I mean, you know, your engine is in good form, but by putting this sort of turbo-charging your life, life expectancy, by adding these compounds you are going to double your advantage.
Interviewer - Meera Senthilingam
Speaking of spicing up life, there's one particular spice, we've forgotten about and that's chilly, which you have actually found has had certain effects in controlling your weight.
Interviewee - Jeya Henry
Some years ago, we showed that eating a few grams of chilli sauce, increases your metabolic rate or what we call diet-induced thermogenesis. So if you think about it, if you eat food and the food that you eat is partly burnt off as what you call dissipated energy, you will have less energy to store as adipose tissue. So our proposal has been that if we eat small amounts of chilli sauce or chilli in your food, it burns up part of your excess energy and therefore leaves you with less energy for storage as adipose issue. So in terms of your strategy eating spiced up food, will not only spice up your life, but also spice up your body weight, in terms of keeping it under shape.
Interviewer - Meera Senthilingam
But to what degree do you think this has a strong effect in controlling someone's weight. I mean, I'm assuming someone can't just stop doing exercise and start eating this.
Interviewee - Jeya Henry
Absolutely, to just give you a simple equation, if you eat only 50 calories per day, that will turn out to be 1500 calories per month, which turns out to be about half a kilo per month in terms of excess body weight consumption, and if you eat these spiced up food, especially chilly, it will burn up about 70 calories extra per day and you can now work out the stoichiometry which says actually that 50 calorie that you had to get rid of, you're now getting rid of by just eating this food. So, in terms of sort of small quantum change that makes a big difference this has got an important attribute.
Interviewer - Meera Senthilingam
So basically, eating a curry on a regular basis could be a good idea and may be adding a touch of cinnamon to that next latte. That was Jeya Henry from Oxford Brookes University, explaining the benefits of spicing up your menu.
(27.09 - The new bond found to hold collagen together)
Interviewer - Meera Senthilingam
When many of us think of collagen, we think cosmetics, skin care, but there are many forms of collagen and now researchers have identified a new bond in one form of collagen, which could help treat a certain autoimmune disease, as well as tell us a lot about the animal kingdom as a whole. Is that right Phil?
Interviewee - Phillip Broadwith
Yes Meera. Billy Hudson, from Vanderbilt University in Tennessee has been studying collagen for 25 years and he has just managed to pin down exactly the bond that holds the whole thing together. It's completely new bond that has never been seen before in any kind of biological molecule. It's a nitrogen-sulphur double bond called the sulfilimine
Interviewer - Meera Senthilingam
Just for the basics first of all, what's collagen IV and what role does it play in animals?
Interviewer - Phillip Broadwith
Well, collagen IV is a particular kind of collagen. We have all heard of collagen for sort of cosmetic implants and they put it in creams and everything now, but there are lots and lots of different kinds of collagen that have different functions around the body. Collagen IV is particularly used in the basement membranes which form the scaffolding that tissues are built up on top of.
Interviewer - Meera Senthilingam
How important is this newly found double bond in this collagen structure?
Interviewee - Phillip Broadwith
Because it's kind of the basic scaffolding that all tissues are built on, knowing how it's held together is very important but there's also a disease called Goodpasture's Syndrome, where our own antibodies attack the collagen structure. So collagen IV has a tail group which is made up of spiralled collagen tails and a head group protein. Two of these head group proteins are held together by this new sulfilimine bond, but if that bond is not present, which it is in Goodpasture's Syndrome, now those head groups aren't held together quite so well and an antibody can get in, bind to those head groups and cause an immune response, which is what the disease is about that the body starts then attacking the basement membrane.
Interviewer - Meera Senthilingam
Did they know how the sulfilimine bond actually forms?
Interviewee - Phillip Broadwith
Well, not for sure, but professor Hudson thinks that it is formed by an enzyme which would fit with the whole Goodpasture's syndrome model because it would be possible that patients affected by Goodpasture's are either missing that enzyme or it's been disabled in some way.
Interviewer - Meera Senthilingam
So is there kind of a main benefit of understanding this bond in targeting Goodpasture's syndrome or there other benefits as well?
Interviewee - Phillip Broadwith
Well, yes. The collagen IV dimers has been implicated in certain cancers as well. So there's possibility of looking at treating those, but also when you find something as widespread as this, I mean first Hudson has got undergraduates from Vanderbilt University looking at tissues from all different kinds of animals and so far they've found them in pretty much everything from sea sponges onwards.
Interviewer - Meera Senthilingam
So if they're present in all these animals, they must obviously play a very important role and so understanding them is crucial.
Interviewee - Phillip Broadwith
Absolutely and also now that this new bond has been identified, the possibility exists that it can be found in other biomolecules, we know what we're looking for now.
(30.20 - Making MOFs more active)
Interviewer - Meera Senthilingam
Well, moving away from animal bonds now, to the world of catalysts where a potential new use has been found or a new location for catalysts that could be very useful, James.
Interviewee - James Mitchell Crow
That's right Meera and that's within MOFs - metal-organic frameworks. Basically what they are is big lattices where basically the corners of the lattice are metal and these are held together by organic arms in a repeating unit - so basically it's a big porous cage like structure. So we talked about gas storage in separation for these type of structures, but now people want to start doing a little bit more than that and making molecules that get absorbed into the structure actually sort of doing some chemistry on them to do that a good way is to incorporate catalysts. People have tried to incorporate catalysts directly into these, sort of, organic arms to hold the structure together, but that can compromise the basic structure.
Interviewer - Meera Senthilingam
So how have they managed now to get a catalyst involved?
Interviewee - James Mitchell Crow
Well, what they have done is incorporated amine groups and nitrogen bearing group into these organic arms and that basically serves as a chemical handle and that you can then attach the catalysts too, so they are sort of done it in a two-stage process. They have reacted those amines with cyclic anhydrides and that basically pops open the cycle and leaves two oxygen bearing arms free and then they can kelite to a metal and it's the metal that is actually the active catalyst. What they've now done is just sort of a proof of concept aldol carbon-carbon bond forming reaction to show that this structure is catalytically active. So you basically flow some reactants in and get the products out the other side.
Interviewer - Meera Senthilingam
So now that they've proved that this is possible and they understand it, how can it be made even better?
Interviewee - James Mitchell Crow
The speculation is that you might be able to incorporate multiple catalysts into the same MOF. So basically you flow in a starting material and get quite a complex product out the other end. A lot of what these have been used for in the past is for storing carbon dioxide. There's a lot of talk about separating carbon dioxide out of flue gases of passage and that's one thing and so if you could sort of absorb that carbon dioxide into the MOF selectively, and then do some sort of reactions with it to turn it into something useful rather than just pumping it underground and hoping it stays there, there will be obviously a great thing to be able to do. So that's a way off, but it's going in the right direction.
Interviewer - Meera Senthilingam
Thanks James.
(32.50 - The chemical conundrum - what did L-cysteine, used in bread making, used to be made from?)
Interviewer - Meera Senthilingam
Now that's pretty much it for this month, but before we go, it's time to catch up with the answer to last month's chemical conundrum. Say what was the question again James?
Interviewee - James Mitchell Crow
Well, it was all to do with brain chemistry and a group of scientists studying the brain had found a way to erase fearful memories in rats and we wanted to know how had they done it?
Interviewee - Bibiana Campos-Seijo
And the answer was by manipulating their dopamine receptors. So dopamine is a neurotransmitting molecule that we all have in our brains and what the group found was that if they block the dopamine receptors exactly 12 hours after scaring the rats, then they quickly forgot what it was that scared them, but instead if they give a chemical which promotes the activity of dopamine, that created a very long-lasting fear in the rats and the timing is also very crucial. If you give the same treatment after 9 hours or 24 hours after scaring the rats, then you don't get the same kind of memory build-up.
Interviewer - Meera Senthilingam
Now what have you got for us, the conundrum this month, James?
Interviewee - James Mitchell Crow
Well, this month's conundrum is about chemistry of bread making. L-Cysteine is often added to dough to speed up the rising process when you are making bread. Until 2001, when a synthetic route to L-Cysteine was invented, L-Cysteine came from a quite intriguing source and we want you to tell us what that was.
Interviewer - Meera Senthilingam
And what enticing prizes do you have in the Chemistry World goodie bag to entice people on doing.
Interviewee - James Mitchell Crow
Well, appropriately enough, we have got a book on bread chemistry, but we also been having a lot fun in the office putting together a visual element, periodic table jigsaw. So we have got one of those jigsaws to give away.
Interviewer - Meera Senthilingam
And how do people go about entering?
Interviewee - James Mitchell Crow
They need to send the answer to chemistryworld at rsc dot org and don't forget to include your address.
Interviewer - Meera Senthilingam
And you can of course also use that address to send us your thoughts, feedback or suggestions for future episodes. That's it for this month, but make sure to join us next month for more of the top stories from the world of chemistry. Contributors this month were James Mitchell Crow, Bibiana Campos-Seijo, Phillip Broadwith and Tom Bond. I'm Meera Senthilingam from the nakedscientists dot com and see you next month.
(Promo)
The Chemistry World podcast is brought to you by the Royal Society of Chemistry, look us up online at chemistryworld dot org.
(End Promo)
