Modulation of lysyl oxidase activity toward peptidyl lysine by vicinal dicarboxylic amino acid residues. Implications for collagen cross-linking.
The substrate specificity of lysyl oxidase has been explored with synthetic oligopeptides. kcat/Km increased with increasing peptide length in Ac-(Gly)n-Lys-(Gly)n-CONH2 (n = 1-5). Using 11-mers as the standard peptide length, Glu immediately N-terminal to Lys increased kcat/Km 8.8-fold over that for the -Lys-Glu- sequence and 4.9-fold over the glutamate-free control. Kinetic constants were significantly less perturbed when Glu was 2 or more residues distant from Lys. Replacement of Glu in -Glu-Lys- with Gln significantly increased Km and lowered kcat/Km. Asp rather than Glu N-terminal to Lys decreased Km similar to that of the -Glu-Lys- 11-mer, although the kcat decreased considerably, indicating that lysyl oxidase responds to the side chain length of vicinal Asp or Glu at this position. -Asp-Glu-Lys- within an 11-mer was not oxidized, although this sequence is oxidized within the N-terminal telopeptide of the alpha 1(I) chain in type I collagen fibrils. Thus, lysyl oxidase exhibits distinct preferences for sequences vicinal to lysine. These results are discussed with respect to a model requiring collagen fibril formation prior to oxidation of lysine in collagen by lysyl oxidase.
Nagan
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Department of Biochemistry, Boston University School of Medicine, Massachusetts 02118.
Kagan
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D000595:Amino Acid Sequence; D000600:Amino Acids, Dicarboxylic / Q000378:metabolism*; D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology; D002417:Cattle; D003094:Collagen / Q000378:metabolism*; D003432:Cross-Linking Reagents; D007700:Kinetics; D008239:Lysine / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D008249:Protein-Lysine 6-Oxidase / Q000378:metabolism*; D013379:Substrate Specificity
D000600:Amino Acids, Dicarboxylic; D003432:Cross-Linking Reagents; D001224:Aspartic Acid; D003094:Collagen; D008249:Protein-Lysine 6-Oxidase; D008239:Lysine