1trz

From Proteopedia

Revision as of 14:58, 15 February 2008

CRYSTALLOGRAPHIC EVIDENCE FOR DUAL COORDINATION AROUND ZINC IN THE T3R3 HUMAN INSULIN HEXAMER

Overview

The T3R3 human insulin hexamer (T and R referring to extended and, alpha-helical conformations, respectively, of the first eight residues of, the B-chain), complexed to two zinc ions, crystallizes in space group R3, with hexagonal cell constants a = 80.64 and c = 37.78 A. The structure has, been refined to a residual of 0.172 using 9225 independent data to 1.6-A, resolution. The asymmetric unit consists of a TR dimer, and the insulin, hexamer is generated by the action of the crystallographic 3-fold axis., The conformation of one insulin trimer is nearly identical to that of the, T6 hexamer, while the other trimer approximates that of the R6 hexamer, except for the three N-terminal B-chain residues that adopt an extended, rather than an alpha-helical conformation. Each of the two zinc ions, which lie on the crystallographic 3-fold axis and exhibit two different, disordered coordination geometries, is coordinated by the imidazole groups, of three symmetry-related B10 histidine residues. The coordination sphere, of the zinc in the T3 trimer is either tetrahedral, with the fourth site, filled by a chloride ion, or octahedral, completed by three water, molecules. The coordination of the zinc in the 12-A narrow channel in the, R3 trimer is tetrahedral, with either a second chloride ion or a water, molecule completing the coordination sphere. The putative off-axial zinc, binding sites that result from the T-->R transition of monomer II do not, contain zinc ion, but instead are filled with clusters of ordered water, molecules.(ABSTRACT TRUNCATED AT 250 WORDS)

Disease

Known diseases associated with this structure: Diabetes mellitus, rare form OMIM:[176730], Hyperproinsulinemia, familial OMIM:[176730], MODY, one form OMIM:[176730]

About this Structure

1TRZ is a Protein complex structure of sequences from [1] with , and as ligands. The following page contains interesting information on the relation of 1TRZ with [Insulin]. Full crystallographic information is available from OCA.

Reference

Crystallographic evidence for dual coordination around zinc in the T3R3 human insulin hexamer., Ciszak E, Smith GD, Biochemistry. 1994 Feb 15;33(6):1512-7. PMID:8312271

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