Please use this identifier to cite or link to this item: http://hdl.handle.net/20.500.12779/3916
Title: Crystal-structure of the Ternary Complex Between Carboxypeptidase-a, L-phenylalanine, and the Azide Ion
Authors: Mangani, Stefano 
P., Orioli
Keywords: x-ray; crystal structure; carboxypeptidase A; inhibitor; ternary complex
Issue Date: 1992
Project: None 
Journal: INORGANIC CHEMISTRY
Abstract: 
The structure of the ternary complex of carboxypeptidase A (CPA) with the amino acid L-phenylalanine and the azide anion is reported as determined by X-ray crystallography to a resolution of 2.0 angstrom. The structure has been refined to an R factor of 0.151 over 7234 reflections having I > 2-sigma(I). The binding of the amino acid molecule to the enzyme hydrophobic pocket closely resembles that of D-phenylalanine with the carboxylate linked to Arg-145 and Asn-144 and its alpha-amino group linked to Glu-270. The azide anion binds to Arg-145, which is proposed as the high-affinity binding site for anions. Upon L-phe binding the Tyr-248 residue moves in the "down" position at contact distances with both the amino and the carboxylate groups of the bound amino acid. A region of electron density near the metal has been interpreted as a second azide ion directly coordinated to zinc as suggested by spectroscopic studies on cobalt-substituted CPA. The present structure confirms the proposed mechanism of CPA sensitivity toward anions.
Description: 
47995
URI: http://hdl.handle.net/20.500.12779/3916
ISSN: 0020-1669
DOI: 10.1021/ic00029a006
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