The characterization of type I and type III collagens from human peripheral nerve

The normal chemical features of peripheral nerve collagens were determined on postmortem, histologically normal adult human femoral nerve. 1. Genetically distinct type I, [alpha1(I)2]alpha2, and type III, [alpha1(III)]3, were isolated by differential salt precipitation and the component subunit chains, alphal(I), alpha2 and alphal(III) were obtained by ion-exchange chromatography and gel filtration. 2. The molecular weight of alphal(I) and alpha2 of type I collagen was 95 000 and that for type III was 280 000. Reduction of type III with dithiothreitol yielded expected alpha1(III) chains of 95 000 molecular weight. 3. The amino acid composition of the three collagen chains, alpha1(I), alpha2, and alpha1(III), was the same as previously reported values for the corresponding chains from human skin except for slightly elevated hydroxylysine content. 4. Peripheral nerve collagen was found to contain 81% type I collagen and 19% type III. These results indicate that peripheral nerve collagen characteristics closely simulate that of human skin and differ from that of human aorta and other parenchymal organs. These data will permit a chemical analysis for possible abnormalities of peripheral nerve collagen in various neurogenic disorders.