1arm
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CARBOXYPEPTIDASE A WITH ZN REPLACED BY HG
OverviewOverview
The crystal structure of the zinc-containing exopeptidase bovine, carboxypeptidase A (CPA) has been refined to high resolution, based on a, data set collected from a single crystal, incorporating new sequence, information based on cloning of the bovine gene. In addition, new refined, structures are available for the zinc-removed form of the enzyme, apo-CPA, as well as the mercury-replaced form, Hg-CPA. The native structure reveals, that the zinc-bound water molecule does not appear to more loosely bound, than the rest of the zinc ligands, at least when B-factor values are, considered. Nor is there any evidence for a secondary location of this, water molecule. The apo-enzyme structure does not show any density in the, place of the removed zinc ion. The only significant change appears to be a, chi2 rotation of one zinc histidine ligand to form an ion-pair interaction, with a glutamic acid side chain. The structure of Hg-CPA reveals a solvent, Tris molecule bound to the mercury cation, as well as an unidentified, cation bound to Glu270. The location of this citation agrees with previous, proposals for the binding side of inhibitory zinc. These observations may, explain some of the differences in kinetics observed in metal- replaced, CPA.
About this StructureAbout this Structure
1ARM is a Single protein structure of sequence from Bos taurus with HG, CU and TRS as ligands. Active as Carboxypeptidase A, with EC number 3.4.17.1 Full crystallographic information is available from OCA.
ReferenceReference
Carboxypeptidase A: native, zinc-removed and mercury-replaced forms., Greenblatt HM, Feinberg H, Tucker PA, Shoham G, Acta Crystallogr D Biol Crystallogr. 1998 May 1;54(Pt 3):289-305. PMID:9867434
Page seeded by OCA on Tue Nov 20 11:04:39 2007