Inhibition of carboxypeptidase A by excess zinc: analysis of the structural determinants by X‐ray crystallography

FEBS Letters

Avilés, Francesc X¹  Gomez-Ortiz, Mariola¹  Huber, Robert²  Gomis-Rüth, Francesc X² 

[1] Departament de Bioquı́mica/Institut de Biologia Fonamental, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain;Max Planck Institut für Biochemie, 82152 Martinsried bei München, Germany

关键词: Metalloenzyme;    Carboxypeptidase A;    Enzyme inhibition;    Zinc inhibition;    X-ray crystallography;   

DOI  :  10.1016/S0014-5793(96)01412-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Pancreatic metallocarboxypeptidases are inhibited by a millimolar excess of zinc together with other exo- and endometalloproteases. We have analyzed the structure of bovine carboxypeptidase A inhibited by an excess of zinc ions using X-ray crystallography at 1.7 Å overall resolution. Under these conditions, a second zinc is observed to bind to the enzyme active site, establishing a distorted tetrahedrally coordinated complex which involves Glu-270 (the general base for catalysis), a water molecule, a chloride ion, and a hydroxide ion. This hydroxide ion forms a 114° angular bridge between the inhibitory and the catalytic zinc ions, which are at a distance of 3.3 Å from one another. The inhibitory zinc holds the hydroxide at nearly the same location as a previously observed active site water molecule (W571) and probably perturbs the substrate positioning and stereochemical rearrangements required for substrate cleavage during catalysis.

【 授权许可】

Unknown