Chemists in India reveal crystal-clear evidence that acrylamide chains form sheet-like structures similar to protein ?-sheets. 

Gangadhar Sanjayan and colleagues at the National Chemical Laboratory in Pune crystallized acrylamide tetramers (molecules made of a chain of four acrylamide units) using a method usually used for protein crystallisation. The researchers analysed the crystals by x-ray diffraction and two dimensional NMR, and found a layered structure, held together by hydrogen-bonds. The researchers claim the structure is 'reminiscent of protein ?-sheets.'

According to Sanjayan the 'stunning observation of sheet conformation' had never been predicted even by computer modelling studies. Sam Gellman, professor of chemistry at the University of Wisconsin, Madison, US, an expert on proteins and protein-like molecules, said the intermolecular hydrogen-bonding patterns discovered 'could not have been predicted, as far as I can see.' Gellman praised the researchers 'very clever' method of preparing the tetramers, as it would have been impossible to get the high resolution structural information using polymers.

Sanjayan said his discovery should help to figure out how the spatial arrangement of atoms and groups in a monomer (the stereochemistry) translates into the final shape of a polymer - a mystery which has yet to be solved for these kinds of molecules. 

Polymers with protein-like shapes might find use in medical applications as peptide replacements with better in vivo stability than their natural counterparts, said Sanjayan. 

Michael J Smith