GLYCINE RESIDUES PROVIDE FLEXIBILITY FOR ENZYME ACTIVE-SITES

The high resolution refined structures of 23 enzymes were analyzed to determine the properties of amino acids involved in active site region s. These regions were found to be rich in G-X-P or Y-X-G oligopeptides , where X and Y are polar and non-polar residues, respectively, that a re small and with low polarity. Other regions of the enzyme molecules have significantly fewer of these sequences, These features suggest th at glycine residues may provide flexibility necessary for enzyme activ e sites to change conformation, and the G-X-Y or Y-X-G oligopeptides m ay be a motif for the formation of enzyme active sites.