Synthesis and conformational study of cuticle collagen models and application as a bioadhesive

Abstract

The synthesis of models of marine cuticle collagens, conformational aspects of native and model proteins and bonding strengths on substrates are investigated. Based on the amino acid composition of acid-soluble cuticle collagen of the Polychaete Nereis japonica, two random-sequence copolypeptides and two repeating-sequence polypetides have been synthesized using N-carboxyanhydride and active-ester methods. Native marine cuticle collagen exhibited a thermally induced conformational transition at a melting temperature (T_m) of 28 °C. Sequential (Ala-Gly-Glu-Hyp-Gly-Gly)₂₁ and (Hyp-Gly-Gly-Glu-Ala-Gly)₁₉ exhibited T_m at 33 and 28 °C, respectively, while no critical T_m was observed in the cases of the random copolypeptides A and B, suggesting that the amino acid sequence plays an important role in the marine cuticle collagen. Adhesive formulations consisting of copoly(Lys¹⁰Tyr¹), native and synthetic model collagens added by oxidase, were found to have the highest tensile shear strength of 5.1 N mm^–2 on iron, while the value for copoly(Lys¹⁰Tyr¹) itself was 2.6 N mm^–2. Mixed adhesive formulations consisting of copoly(Lys¹⁰Tyr¹) and collagens (native and synthetic) showed tensile shear strengths of 3.2–3.9 N mm^–2 on iron. The effect of oxidase to increase the bonding strength was observed in general but the bonding strengths of the adhesive formulation consisting of both native and synthetic cuticle collagens were weaker on alumina, skin and bone than those on iron. The results of this study have been compared to those for bonding strengths of commercial gelatin from cattle bone.