Crystal structure of a helical oligopeptide model of polyglycine II and of other polyamides: acetyl-(glycyl-beta-alanyl)2-NH propyl.
We synthesized and solved the crystalline structure of the oligopeptide acetyl-(glycyl-beta-alanyl)2-NH propyl. The crystal is formed by layers of helical molecules with the same chirality; however, right-handed layers alternate with left-handed ones. Inside every layer, the packing of helices is pseudohexagonal with hydrogen bonds between neighbor molecules. The structure found affords direct support for the model proposed by Crick and Rich for polyglycine II and also provides an interpretation for the structure of a newly found family of polyamides that do not form sheets as observed in most nylon structures.
Amino Acid Sequence↗