Inhibition of Streptomyces griseus aminopeptidase and effects of calcium ions on catalysis and binding--comparisons with the homologous enzyme Aeromonas proteolytica aminopeptidase

• Published in: European journal of biochemistry Vol. 258; no. 2; pp. 313 - 319
• Main Authors: Papir, G, Spungin-Bialik, A, Ben-Meir, D, Fudim, E, Gilboa, R, Greenblatt, H M, Shoham, G, Lessel, U, Schomburg, D, Ashkenazi, R, Blumberg, S
• Format: Journal Article
• Language: English
• Published: England 01.12.1998
• Subjects: Aeromonas - enzymology; Aeromonas proteolytica; aminopeptidase; Aminopeptidases - chemistry; Anilides - metabolism; Anti-Bacterial Agents - pharmacology; Bacterial Proteins - chemistry; Binding Sites - physiology; Calcium - pharmacology; Enzyme Inhibitors - pharmacology; Enzyme Stability - drug effects; Kinetics; Leucine - analogs & derivatives; Leucine - pharmacology; Metalloproteins - chemistry; Models, Molecular; Molecular Structure; Peptides; Protein Binding; Protein Structure, Tertiary; Streptomyces griseus; Streptomyces griseus - enzymology; Substrate Specificity
• ISSN: 0014-2956; 1432-1033
• DOI: 10.1046/j.1432-1327.1998.2580313.x

Streptomyces griseus aminopeptidase is a zinc metalloenzyme containing 2 mol zinc/mol protein, similar to the homologous enzyme Aeromonas proteolytica aminopeptidase. In addition, a unique Ca2+-binding site has been identified in the Streptomyces enzyme, which is absent in the Aeromonas enzyme. Binding of Ca2+ enhances stability of the Streptomyces enzyme and modulates its activity and affinity towards substrates and inhibitors in a structure-dependent manner. Among the three hydrophobic 4-nitroanilides of alanine, valine and leucine, the latter displays the largest overall activation (increase in k(cat)/Km). Large enhancements in affinity (1/Ki) upon Ca2+ binding have been observed for inhibitors with flexible (leucine-like) residues at their N-termini and smaller enhancements for inhibitors with rigid (phenylalanine-like) residues.