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spinqualitylabelsall models 1mdc, resolution 1.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTALLIZATION, STRUCTURE DETERMINATION AND LEAST-SQUARES REFINEMENT TO 1.75 ANGSTROMS RESOLUTION OF THE FATTY-ACID-BINDING PROTEIN ISOLATED FROM MANDUCA SEXTA L

Overview

The molecular structure of an insect fatty-acid-binding protein isolated, from Manduca sexta L. has been determined and refined to a nominal, resolution of 1.75 A. Crystals used in the investigation were grown from, 1.6 M-ammonium sulfate solutions buffered at pH 4.5 with 50 mM-sodium, succinate, and belonged to space group P2(1) with unit cell dimensions of, a = 27.5 A, b = 71.0 A, c = 28.7 A and beta = 90.8 degrees. An electron, density map, phased with four heavy-atom derivatives and calculated to 2.5, A resolution, allowed for complete tracing of the 131 amino acid residue, polypeptide chain. Subsequent least-squares refinement of the model, reduced the R-factor from 46.0% to 17.3% using all measured X-ray data, from 30.0 A to 1.75 A. Approximately 92% of the amino acid residues fall, into classical secondary structural elements including ten strands of, anti-parallel beta-pleated sheet, two alpha-helices, one type I turn, three type II turns, four type II' turns and one type III turn. As in, other fatty-acid-binding proteins, the overall molecular architecture of, the insect molecule consists of ten strands of anti-parallel beta-pleated, sheet forming two layers that are nearly orthogonal to one another. A, helix-turn-helix motif at the N-terminal portion of the protein flanks one, side of the up-and-down beta-barrel. The functional group of the fatty, acid is within hydrogen-bonding distance of Gln39, Tyr129, Arg127 and a, sulfate molecule, while the aliphatic portion of the ligand is surrounded, by hydrophobic amino acid residues lining the beta-barrel. The binding of, the carboxylic acid portion of the ligand is very similar to that observed, in P2 myelin protein and the murine adipocyte lipid-binding protein, but, the positioning of the hydrocarbon tail after approximately C6 is, completely different.

About this Structure

1MDC is a Single protein structure of sequence from Manduca sexta with SO4, ACE and PLM as ligands. Full crystallographic information is available from OCA.

Reference

Crystallization, structure determination and least-squares refinement to 1.75 A resolution of the fatty-acid-binding protein isolated from Manduca sexta L., Benning MM, Smith AF, Wells MA, Holden HM, J Mol Biol. 1992 Nov 5;228(1):208-19. PMID:1447782

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