Effects of pH on the structure and function of carboxypeptidase A: crystallographic studies

G. Shoham, D. C. Rees, W. N. Lipscomb

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

High-resolution crystal structures are described for carboxypeptidase A (EC 3.4.17.1) in crystals grown at pH 8.5, 9.0, and 9.5 and compared with the structure at pH 7.5. The comparison shows that in the pH range of 7.5-9.5 the enzyme structure is practically unchanged, and, most importantly, that the flexible side chain of Tyr-248 remains exclusively in the 'up' position, away from the Zn atom, throughout the pH range. There is no evidence for binding of Tyr-248 to Zn at any of these pH values. We conclude that the interaction of Tyr-248 with Zn is not an essential part of the mechanism of carboxypeptidase A and that its occurrence is an artifact of chemical modification of Tyr-248. It is also suggested that Tyr-248 is not uniquely associated with the observed high pK of the enzymatic hydrolysis.

Original languageAmerican English
Pages (from-to)7767-7771
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume81
Issue number24 I
DOIs
StatePublished - 1984
Externally publishedYes

Fingerprint

Dive into the research topics of 'Effects of pH on the structure and function of carboxypeptidase A: crystallographic studies'. Together they form a unique fingerprint.

Cite this