Cuticle structure of squid Illex argentinus pen

Abstract

The cuticle structure of squid Illex argentinus pen was investigated by enzymatic hydrolysis, amino acid analysis, scanning electron micrography observation and electrophoresis of proteins in each enzyme(s)-treated squid pen. It is suggested that a thin layer of collagen-like substance was coated outside the pen, which comprised 22% of total protein in the pen. Under this layer, there was a row of chitinous lamella (1.7 μm for each lamellae). A number of cuneiform protein particles (0.1 x 0.3 μm) that could not be hydrolyzed by collagenase but could be hydrolyzed by alcalase were bound to the lamella. The spaces (0.5 μm) between each two lamella were filled with proteins. These proteins included those that could be hydrolyzed by alcalase and those that could not be hydrolyzed by alcalase, nor be dissolved in phosphate buffer solution.