3mth

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spinqualitylabelsall models 3mth, resolution 1.9Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

X-RAY CRYSTALLOGRAPHIC STUDIES ON HEXAMERIC INSULINS IN THE PRESENCE OF HELIX-STABILIZING AGENTS, THIOCYANATE, METHYLPARABEN AND PHENOL

Overview

Three X-ray crystallographic studies have been carried out on pig insulin, in the presence of three ligands, thiocyanate, methylparaben (methyl, p-hydroxybenzoate), and phenol. In each case, rhombohedral crystals were, obtained, which diffracted to 1.8, 1.9, and 2.3 A, respectively. Each, crystal structure was very similar to that of 4-zinc pig insulin, which, was used as a starting model for PROLSQ refinement (Collaborative, Computational Project, Number 4, 1994). The R factors for the refined, structures of thiocyanate insulin, methylparaben insulin, and phenol, insulin were 19.6, 18.4, and 19.1, respectively. Each crystal structure, consists of T3R3f insulin hexamers with two zinc ions per hexamer. In the, R3f trimer of the thiocyanate insulin hexamer, one thiocyanate ion is, coordinated to the zinc on the hexamer 3-fold axis, but there is no, evidence of zinc ion binding in the off-axis zinc ion sites seen in the, 4-zinc pig insulin structure. In the methylparaben insulin and phenol, insulin hexamers, the phenolic ligands are bound at the dimer-dimer, interfaces in the R3f trimers in a manner similar to that of phenol in R6, phenol insulin. The binding of methylparaben appears to make the hexamer, more compact by drawing the A and the B chains closer together in the, binding site. In all three structures presented herein, the conformations, of the first three residues of the B chain in the R3f trimer are extended, rather than alpha-helical, as is seen in R6 phenol insulin. The energetics, of ligand binding in the insulin hexamer are discussed.

About this Structure

3MTH is a Protein complex structure of sequences from Sus scrofa with ZN, CL and MPB as ligands. This structure superseeds the now removed PDB entry 2MTH. Full crystallographic information is available from OCA.

Reference

X-ray crystallographic studies on hexameric insulins in the presence of helix-stabilizing agents, thiocyanate, methylparaben, and phenol., Whittingham JL, Chaudhuri S, Dodson EJ, Moody PC, Dodson GG, Biochemistry. 1995 Nov 28;34(47):15553-63. PMID:7492558

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