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Using automated stepwise Edman degradation of suitable overlapping peptides, the complete amino acid sequence of the 268 residue peptida α1-CB7 from calf skin collagen was determined. The preparation and ordering of the chymotryptic, tryptic and thermolytic peptides is described in the preceding paper. As shown previously for other peptides from the helical region of collagen, glycine appears in every third position and proline is present in high amount. Hydroxylation of proline to 4-hydroxyproline and lysine to hydroxylysine only occurred in the Y position of the tripeptide unit Gly-X-Y. Non-random distribution of other amino acids between the X and Y positions was also observed. [ABSTRACT FROM AUTHOR]

Sequencing of chyinotrypsin, trypsin, collagenase- and hydroxylamine-derived peptides, using the automated Edman degradation procedure, yielded the complete amino acid sequence of α2-CB4 from calf skin collagen (321 residues). Together with the data from earlier work, an uninterrupted sequence in the helical region of the α2-chain from residues 1-393 is now known. Glycine is found in every third position of the peptide. Hydroxylation of proline and lysine occurs only in the Y-position of the triplet Gly-X-Y and is not complete in every position. Some residues, such as glutamic acid, leucine, phenylalanine and arginine, are distributed non-randomly between the X and Y-positions and this non-random distribution is different in the α1 and α2-chains. Comparison of the N-terminal 393 residues from the helical region of the α1 and α2-chains revealed a nearly identical distribution of charged polar residues arginine, lysine, glutamic and aspartic acids. The distribution of the triplet Gly-Pro-Hyp is similar in both chains. The remaining residues in the α2-chain exhibit a high degree of substitutions when compared with those in the α1-chain. Approximately one in every two residues in both the X and Y-positions are substituted. [ABSTRACT FROM AUTHOR]