Their weak spot, however, is that they aren’t designed to survive outside the body and tend to decompose if not kept at the correct temperature and acidity. This presents a challenge if we want to use them in medicine or synthesis.
"Enzymes are some of the most selective and efficient catalysts – reactors to facilitate chemical synthesis", explains Christian Doonan from the University of Adelaide, Australia. "However, due to their fragility they need to be protected from the harsher solvents and non-physiological conditions used in industrial synthesis."
One strategy for overcoming this problem is to encapsulate the enzyme in something more resilient. Chemical scientists often use a porous, crystalline material called a metal-organic framework (MOF) for this purpose. The challenge is how to get the enzyme into the MOF shell. Certain proteins have a particular structure which means that, when they come into contact with the MOF, the MOF crystallises into a shell around the enzyme. However, until now this has only worked for specific proteins with specific properties.
Now, Christian and his team have developed a simple modification to make this work for any protein. "The research shows that a simple chemical modification to the surface of a protein can reliably induce crystallisation of a protective MOF shell around the protein and stabilise it when exposed to inhospitable conditions", he says.
Christian explains how this encapsulation technique could make it easier for enzymes to be used in medicines. "Proteins denature under elevated temperatures. However, when tightly encapsulated within the MOF crystal the protein maintains its structure when heated. Thus, transport of proteins could be carried out efficiently and inexpensively without the need to maintain low temperatures."
The technique could also be used for evidence preservation in forensics labs, where biological material is often stored for long periods.
This article is free to read: Natasha Maddigan et al., Chem. Sci. 2018, DOI: 10.1039/C8SC00825F