Isolation of the alpha 3-chain of human type V collagen and characterization by partial sequencing

The alpha 1 alpha 2 alpha 3-chain form of human type V collagen was solubilized from placenta by pepsin treatment and isolated by ion-exchange chromatography. The alpha 3-chain was further separated after denaturation of the triple helix also by ion-exchange chromatography, cleaved with lysyl endopeptidase and the fragments separated by size-exclusion chromatography and reversed phase HPLC. N-Terminal sequence analysis of the fragments and comparison to sequences contained in a database indicated a relatively high similarity of the alpha 3(V)-chain to alpha 1(V) and alpha 1(XI) with an identity of approximately 73%.