Studies on the additional peptide of procollagen extracted from chick embryo cartilage.

The additional peptide of procollagen is thought to play an important role in its synthesis, and attempts were made to elucidate the chemical properties of the additional peptide, particularly in regard to the possible existence of sugar substituents. Labeled procollagens were obtained with 4 M guanidine.HCl from chick embryo epiphyseal cartilages which had been incubated with [14C] proline, [14C] tryptophan or [14C] glucose. Each of the procollagen samples was digested with bacterial collagenase, and then chromatographed on 0.1% SDS.Sephadex G-150. The [ 14 C] glucose-labeled sample yielded a fraction with the size of additional peptide (molecular weight, 13,200), plus collagenase-digestible small peptides. The peptide was distinct from the collagenase.sensitive region (Q.region) in having [14C] tryptophan. On acid hydrolysis of the additional peptide samples, radioactive glucose, galactose, mannose and a small amount of glucosamine were recovered on paper chromatography and paper electrophoresis. Mannose and glucosamine are the components not found in the authentic Q-chain of type II collagen. The results demonstrate that the additional peptide of cartilage procollagen is different from the 0:1(11) chain in amino acid composition and also in the type of sugars attached.