Structural analysis of the extension peptides on matrix forms of type V collagen in fetal calf bone and skin

The structure of the extension peptides retained on the tissue form of type V collagen molecules was determined. Type V collagen α chains containing extension peptides were extracted from fetal calf skin and bone by 4 M guanidine-HCl and 0.5 M acetic acid, respectively. Collagens present in both extracts were fractionated by sodium chloride precipitation. The collagen α(V) chains were then resolved by reverse-phase high performance liquid chromatography. The N-terminal extension peptides were characterized by direct sequence analysis after deblocking with pyroglutamate amino-peptidase and analysis of the products of digestion by bacterial collagenase, chymotrypsin, V8 protease and endoproteinase Lys-C. The results showed that the retained extension peptides on type V collagen molecules in the extracellular matrix of skin and bone were amino-properties and that the α2(V) chain retains an intact amino-propeptide while the α1(V) chain appears to be partially processed. The extended α1(V) chain isolated from fetal calf bone gave an identical amino-terminal sequence to that of the α1(V) chain isolated from fetal calf skin, suggesting that a specific enzyme may be involved in processing the α1(V) amino-propeptide.