1o9x

From Proteopedia

Revision as of 14:42, 5 November 2007

HUMAN SERUM ALBUMIN COMPLEXED WITH TETRADECANOIC ACID (MYRISTIC ACID) AND HEMIN

Overview

BACKGROUND: Human serum albumin (HSA) is an abundant plasma protein that, binds a wide variety of hydrophobic ligands including fatty acids, bilirubin, thyroxine and hemin. Although HSA-heme complexes do not bind, oxygen reversibly, it may be possible to develop modified HSA proteins or, heme groups that will confer this ability on the complex. RESULTS: We, present here the crystal structure of a ternary HSA-hemin-myristate, complex, formed at a 1:1:4 molar ratio, that contains a single hemin group, bound to subdomain IB and myristate bound at six sites. The complex, displays a conformation that is intermediate between defatted HSA and, HSA-fatty acid complexes; this is likely to be due to low myristate, occupancy in the fatty acid binding sites that drive the conformational, change. The hemin group is bound within a narrow D-shaped hydrophobic, cavity which usually accommodates fatty acid; the hemin propionate groups, are coordinated by a triad of basic residues at the pocket entrance. The, iron atom in the centre of the hemin is coordinated by Tyr161. CONCLUSION:, The structure of the HSA-hemin-myristate complex (PDB ID 1o9x) reveals the, key polar and hydrophobic interactions that determine the hemin-binding, specificity of HSA. The details of the hemin-binding environment of HSA, provide a structural foundation for efforts to modify the protein and/or, the heme molecule in order to engineer complexes that have favourable, oxygen-binding properties.

About this Structure

1O9X is a Single protein structure of sequence from Homo sapiens with MYR and HEM as ligands. Structure known Active Site: AC1. Full crystallographic information is available from OCA.

Reference

Crystal structural analysis of human serum albumin complexed with hemin and fatty acid., Zunszain PA, Ghuman J, Komatsu T, Tsuchida E, Curry S, BMC Struct Biol. 2003 Jul 7;3:6. Epub 2003 Jul 7. PMID:12846933

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