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Effects of pH on the Structure and Function of Carboxypeptidase A: Crystallographic Studies

Shoham, G. and Rees, D. C. and Lipscomb, W. N. (1984) Effects of pH on the Structure and Function of Carboxypeptidase A: Crystallographic Studies. Proceedings of the National Academy of Sciences of the United States of America, 81 (24). pp. 7767-7771. ISSN 0027-8424. PMCID PMC392233. https://resolver.caltech.edu/CaltechAUTHORS:20150210-094928604

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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.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://www.pnas.org/content/81/24/7767PublisherArticle
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC392233/PubMed CentralArticle
ORCID:
AuthorORCID
Rees, D. C.0000-0003-4073-1185
Additional Information:© 1984 National Academy of Sciences. Contributed by W. N. Lipscomb, August 27, 1984. We are grateful to Drs. R. B. Honzatko, M. Lewis, L. C. Kuo, and W. Bennett for helpful discussion and experimental assistance. We thank the National Institutes of Health (GM 06920) for support and the National Science Foundation (PCM-77-11398) for the computational facilities. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Funders:
Funding AgencyGrant Number
NIHGM 06920
NSFPCM-77-11398
Subject Keywords:enzyme activity; proteases; protein crystallography; activity of enzymes in solution and crystals
Issue or Number:24
PubMed Central ID:PMC392233
Record Number:CaltechAUTHORS:20150210-094928604
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150210-094928604
Official Citation:G Shoham, D C Rees, and W N Lipscomb Effects of pH on the structure and function of carboxypeptidase A: crystallographic studies PNAS 1984 81 (24) 7767-7771
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54641
Collection:CaltechAUTHORS
Deposited By: SWORD User
Deposited On:11 Feb 2015 00:31
Last Modified:03 Oct 2019 07:59

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