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The Role of Zinc in Angiotensin Converting Enzyme
Author(s) -
Bünning Peter,
Riordan James F.
Publication year - 1981
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198100011
Subject(s) - chemistry , zinc , enzyme , substrate (aquarium) , hydrolysis , chelation , catalysis , dissociation constant , manganese , cobalt , chloride , inorganic chemistry , biochemistry , organic chemistry , receptor , oceanography , geology
Angiotensin converting enzyme is a chloride‐dependent zinc metalloexo‐peptidase. The zinc atom is essential for enzymatic activity. Removal of zinc by dialysis against the chelating agent 1,10‐phenanthroline abolishes activity toward the chromophoric substrates furanacryloyl‐Phe‐Gly‐Gly. Reconstitution of the resultant apoenzyme with either zinc, cobalt or manganese restores activity to 100, 55 or 25% of that of the native enzyme, respectively. Spontaneous dissociation of zinc from the enzyme occurs below pH 7 and this can be prevented by adding excess metal to the buffer. Radiationless energy transfer studies with a fluorescent substrate demonstrate that zinc is not required for substrate binding and does not mediate the activating effect of chloride. Thus, zinc functions solely in the hydrolytic step of catalysis.