Aldehyde content and cross-linking of type III collagen

Abstract

Summary The aldehyde content and crosslink characteristics of Type III collagen, extracted from fetal calf skin, have been examined by employing NaB 3 H 4 reduction. Direct comparison was made with Type I collagen from the same preparation of fetal calf skin. Collagen molecules and reconstituted collagen fibrils were assayed for tritium incorporation and for their content of reduced aldehydes and crosslinks. Type III collagen incorporated about 45% of the tritium found in Type I collagen and lysinonorleucine was the major crosslink in reconstituted Type III collagen fibrils. In contrast, reconstituted fibrils of Type I collagen primarily formed hydroxylysinonorleucine. These results demonstrate that Type III collagen resembles all other collagen isotypes by containing crosslinking aldehydes but that it differs from them by the predominance of lysinonorleucine. This difference may be related to the turnover and progrressive loss of Type III collagen in developing tissues.