Conchiolin-protein in aragonite shells of mollusks

Conchiolin is partially dissolved from 12 species of mollusks representing 7 families. Nacreous conchiolin proteins separate by PAGE into a consistent electromorph pattern. Protein bands H (high), M (medium) and L (low) have molecular weights of 37,800, 23,200, and 19,600, respectively. Protein analysis for amino acid content indicates the principal protein in band H is both aliphatic and basic. Five amino acids account for 87% of the total 100% in protein H on a mole fraction basis, namely: glycine (29%), valine (24%), leucine (8.3%), lysine (21%), and arginine (4.3%). Aspartic and glutamic acids combined total less than 1%. A plausible molecular model is advanced for protein relationships in the nacreous layers of mollusk shells. The template model may account for the crystallization oi calcium carbonate into an aragonite structure in contrast to calcite crystals. Copyright (C) 1996 Elsevier Science Inc.