Polypeptide chains with similar amino acid sequences but a distinctly different conformation

Abstract

The primary structures of bovine and porcine pancreatic phospholipase A₂ differ only by about 15%. Nevertheless, a 12 residue loop, with only one substitution (Val→Phe) has a quite different conformation, whereas the rest of the molecules have a very similar folding indeed. From this observation it is concluded that prediction of a 3‐dimensional structure on the basis of sequence similarity of short segments alone might give erroneous results.