Analogous salicylic acid affinity regions in serum albumin and soybean β‐Conglycinin

Abstract

AbstractThe known structures of human serum albumin and its binding sites for salicylic acid (SA) were used as a model for examining the amino acid sequence of soybean β‐conglycinin to determine whether a plant protein might share structural similarities with albumin relative to the binding of SA, Molecular mechanics energy calculations for computed nonionized and ionized interactions in vacuo identified the two major SA affinity regions in human serum albumin and a single analogous region in the α‐subunit of soybean β‐conglycinin. SA interactions with 21‐residue segments from both proteins suggest redundant binding sites with multiple degrees of affinity. Highaffinity segments incorporate hydrophobic amino acids with combinations or multiple residues of histidine, tryptophan, lysine, or arginine in keeping with a preference of SA for homopolymers of these acids over other homopolypeptides. Residue spacing also seems important. High affinity is associated with but not imparted by genetic similarity. Profiles from β‐sheet conformations simplify identification of analogous segments.