Similarity of different β‐strands flanked in loops by glycines and prolines from distinct (α/β)₈‐barrel enzymes: Chance or a homology?

Abstract

Many (a/&barrel enzymes contain their conserved sequence regions at or around the 0-strand segments that are often preceded and succeeded by glycines and prolines, respectively. a-Amylase is one of these enzymes. Its sequences exhibit a very low degree of similarity, but strong conservation is seen around its &strands. These conserved regions were used in the search for similarities with P-strands of other (a/&-barrel enzymes. The analysis revealed an interesting similarity between the segment around the 02-strand of a-amylase and the one around the P4-strand of glycolate oxidase that are flanked in loops by glycines and prolines. The similarity can be further extended on other members of the a-amylase and glycolate oxidase subfamilies, i.e., cyclodextrin glycosyltransferase and oligo-l,6-glucosidase, and flavocytochrome b2, respectively.