1can

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spinqualitylabelsall models 1can, resolution 1.9Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTALLOGRAPHIC STUDIES OF THE BINDING OF PROTONATED AND UNPROTONATED INHIBITORS TO CARBONIC ANHYDRASE USING HYDROGEN SULPHIDE AND NITRATE ANIONS

Contents 1 Overview 2 Disease 3 About this Structure 4 Reference

Overview

The structures of human carbonic-anhydrase-II complexes with the anionic, inhibitors hydrogen sulphide (HS-) and nitrate (NO3-) have been determined, by X-ray diffraction at 0.19-nm resolution from crystals soaked at pH 7.8, and 6.0, respectively. The modes of binding of these two anions differ, markedly from each other. The strong inhibitor HS- replaces the native, zinc-bound water/hydroxide (Wat263) leaving the tetrahedral metal geometry, unaltered and acts as a hydrogen-bonding donor towards Thr199 gamma. The, weak NO3- inhibitor does not displace Wat263 from the metal coordination, but occupies a fifth binding site changing the zinc coordination, polyhedron into a slightly distorted trigonal bipyramid. The interaction, of NO3- with the metal is weak; the nearest of its oxygen atoms being at a, distance of 0.28 nm from the zinc ion. The binding of nitrate to the, enzyme is completed by a hydrogen bond to the metal coordinated Wat263 and, a second one to a water molecule of the active-site cavity. The structures, of the two complexes help to rationalize the binding of anionic inhibitors, to carbonic anhydrase and the binding mode displayed by NO39 may be, relevant to the catalytic mechanism.

Disease

Known disease associated with this structure: Osteopetrosis, autosomal recessive 3, with renal tubular acidosis OMIM:[611492]

About this Structure

1CAN is a Single protein structure of sequence from Homo sapiens with HG, NO3 and ACE as ligands. Active as Carbonate dehydratase, with EC number 4.2.1.1 Full crystallographic information is available from OCA.

Reference

Crystallographic studies of the binding of protonated and unprotonated inhibitors to carbonic anhydrase using hydrogen sulphide and nitrate anions., Mangani S, Hakansson K, Eur J Biochem. 1992 Dec 15;210(3):867-71. PMID:1336460

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