Bovine renal cortex type I collagen: high contents of 3- and 4-hydroxyprolines

Type I collagen was prepared from bovine renal cortices by pepsin digestion followed by differential salt fractionation, and was identified by SDS-polyacrylamide gel electrophoresis, CM-cellulose chromatography, and by the analysis of CNBr-cleavage products of the alpha 1 chain. About 61-87% of total collagen in the tissue was solubilized by this procedure and type I collagen represents about 40% of the collagen solubilized. Renal cortex type I collagen is characteristic in that the extent of hydroxylation of the prolyl residues is high, but that of the lysyl residues is at the same level as in skin. Tissue-specific differences in the hydroxylation of prolyl residues of type I collagen are also discussed.