Biochemical and Immunochemical Characterization of Guanidine Hydrochloride-Soluble Collagen in the Mantle Muscle of Squid Todarodes pacificus

Abstract

Approximately 8% of the total collagen in the mantle muscle of the squid Todarodes pacificus was solubilized by extraction with 50 mM Tris-HCl, pH 7.5, containing 4M guanidine hydrochloride (G/HCl). The G/HCl-soluble collagen (GSC) was partially characterized by biochemical and immunochemical techniques for the purpose of obtaining information on the structure of intact collagen in the squid muscle. The GSC showed four a chain-sized components, termed chains e, f, g, and h, in SDS-PAGE. The SDS-PAGE pattern was changed by pepsin digestion to show quite a similar pattern to that of Type SQ-II collagen (quantitatively minor collagen) from pepsin-solubilized collagen. The pepsin-digested GSC and the pepsin-solubilized Type SQ-II collagen displayed quite similar peptide maps with lysyl endopeptidase and V-8 protease to each other. These results indicated that the GSC consisted predominantly of intact Type SQ-II collagen. In addition, the chains e and g were identified as intact forms of α1(SQ-II) and α2(SQ-II) components, respectively, by peptide mapping and immunoblot analysis of the GSC and its pepsin digests.