The Role of Zinc in Angiotensin Converting Enzyme

Israel Journal of Chemistry - Tập 21 Số 1 - Trang 43-47 - 1981
Peter Bünning1, James Riordan1
1Biophysics Research Laboratory, Brigham and Woman's Hospital, and Department of Biological Chemistry, Harvard Medical School, Boston, MA 02115 USA

Tóm tắt

AbstractAngiotensin 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.

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Tài liệu tham khảo

Abbreviations: ACE angiotensin converting enzyme; EDTA ethylenediamine tetraacetic acid; FA‐ furanacryloyl‐; dansyl 5‐dimethylaminonaphthalene‐1‐sulfonyl‐; Hepes hydroxyethylpiperazine ethanesulfonate; Mes morpholinoethanesulfonate.

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This fluorescent substrate was employed in this study primarily because it was available in reasonable quantities and had good solubility characteristics. Additional studies with a series of dansyl tripeptides will be carried out in the near future.

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Israel Journal of Chemistry

Tập 21 Số 1

43-47

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