Chemical modification of the monkey brain cytosolic aminopeptidase that cleaves enkephalin to its constituent amino acids. Evidence for essential tyrosine residue (residues).
A cytosolic monkey brain aminopeptidase is known to cleave amino acids sequentially from the amino termini of peptides like enkephalins, angiotensins, and tuftsin. This enzyme is stimulated by ATP-Mg2+ and inactivated by cyclic AMP-dependent phosphorylation. Chemical modification of this aminopeptidase by several amino acid-modifying agents indicated essential lysine, histidine, arginine, cysteine, and tyrosine residues. The involvement of tyrosine residues in the catalytic activity was confirmed by modification by N-acetylimidazole and acetic anhydride, hydroxylamine treatment, and absorbance studies. Moreover, acetic-1-14C anhydride could label the enzyme that was inhibited by ATP or by bestatin, a competitive inhibitor of the enzyme.
Ramamoorthy
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Neurochemistry Laboratory, Christian Medical College and Hospital, Vellore, India.
Balasubramanian
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AS
D000089:Acetic Anhydrides; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002384:Catalysis; D004745:Enkephalins / Q000378:metabolism*; D000882:Haplorhini / Q000378:metabolism*; D019811:Hydroxylamine; D006898:Hydroxylamines; D007093:Imidazoles; D007931:Leucyl Aminopeptidase / Q000737:chemistry*; D010779:Photofluorography; D013439:Sulfhydryl Reagents; D014443:Tyrosine / Q000737:chemistry*
D000089:Acetic Anhydrides; D000596:Amino Acids; D004745:Enkephalins; D006898:Hydroxylamines; D007093:Imidazoles; D013439:Sulfhydryl Reagents; C031800:acetic anhydride; D019811:Hydroxylamine; D014443:Tyrosine; D007931:Leucyl Aminopeptidase; C012160:N-acetylimidazole