5cpa
From Proteopedia
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REFINED CRYSTAL STRUCTURE OF CARBOXYPEPTIDASE A AT 1.54 ANGSTROMS RESOLUTION.
Overview
The crystal structure of bovine carboxypeptidase A (Cox) has been refined, at 1.54 A resolution using the restrained least-squares algorithm of, Hendrickson & Konnert (1981). The crystallographic R factor (formula; see, text) for structure factors calculated from the final model is 0.190. Bond, lengths and bond angles in the carboxypeptidase A model have, root-mean-square deviations from ideal values of 0.025 A and 3.6 degrees, respectively. Four examples of a reverse turn like structure (the "Asx", turn) requiring an aspartic acid or asparagine residue are observed in, this structure. The Asx turn has the same number of atoms as a reverse, turn, but only one peptide bond, and the hydrogen bond that closes the, turn is between the Asx side-chain CO group and a main-chain NH group. The, distributions of CO-N and NH-O hydrogen bond angles in the alpha-helices, and beta-sheet structures of carboxypeptidase A are centered about 156, degrees. A total of 192 water molecules per molecule of enzyme are, included in the final model. Unlike the hydrogen bonding geometry observed, in the secondary structure of the enzyme, the CO-O(wat) hydrogen bond, angle is distributed about 131 degrees, indicating the role of the lone, pair electrons of the carbonyl oxygen in the hydrogen bond interaction., Twenty four solvent molecules are observed buried within the protein., Several of these waters are organized into hydrogen-bonded chains, containing up to five waters. The average temperature factor for atoms in, carboxypeptidase A is 8 A2, and varies from 5 A2 in the center of the, protein, to over 30 A2 at the surface.
About this Structure
5CPA is a Single protein structure of sequence from Bos taurus with ZN as ligand. Active as Carboxypeptidase A, with EC number 3.4.17.1 Full crystallographic information is available from OCA.
Reference
Refined crystal structure of carboxypeptidase A at 1.54 A resolution., Rees DC, Lewis M, Lipscomb WN, J Mol Biol. 1983 Aug 5;168(2):367-87. PMID:6887246
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