Peptide Mapping of Cornea Collagens from Chick Embryos by Dodecylsulfate/Polyacrylamide Gel Electrophoresis

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Abstract
Using differential salt fractionation, different collagen types were obtained from corneas of 17 day old chick embryos. The collagen precipitated by 1.7 M and 2.5 M NaCl consisted of type I collagen, having an .alpha.1:.alpha.2 ratio of 2. The collagen precipitated by 5 M NaCl contained .alpha.A, .alpha.B, .alpha.1 and .alpha.2 chains having an .alpha.A:.alpha.B ratio of 1 and an .alpha.1:.alpha.2 ratio of 10. The .alpha.1 and .alpha.2 chains isolated from corneas had higher mobility in polyacrylamide gel electrophoresis in sodium dodecylsulfate compared to that of their counterparts isolated from embryonic chick tendons. When the .alpha.1 and .alpha.2 chains isolated by polyacrylamide gel electrophoresis in sodium dodecylsulfate were subjected to limited protease degradations, the peptide maps obtained from corneal .alpha. chains were not identical to those of tendon .alpha. chains. Apparently, type I collagen in cornea is different from type I collagen in tendon. Apparently, the .alpha.1 chain present in the 5 M NaCl precipitate is a type I .alpha.1 chain.