1g0a

From Proteopedia

Revision as of 13:50, 15 February 2008

CARBONMONOXY LIGANDED BOVINE HEMOGLOBIN PH 8.5

Overview

Initial crystallographic studies suggested that fully liganded mammalian, hemoglobin can adopt only a single quaternary structure, the quaternary R, structure. However, more recent crystallographic studies revealed the, existence of a second quaternary structure for liganded hemoglobin, the, quaternary R2 structure. Since these quaternary structures can be, crystallized, both must be energetically accessible structures that, coexist in solution. Unanswered questions include (i) the relative, abundance of the R and R2 structures under various solution conditions and, (ii) whether other quaternary structures are energetically accessible for, the liganded alpha(2)beta(2) hemoglobin tetramer. Although, crystallographic methods cannot directly answer the first question, they, represent the most direct and most accurate approach to answering the, second question. We now have determined and refined three different, crystal structures of bovine carbonmonoxyhemoglobin. These structures, provide clear evidence that the dimer-dimer interface of liganded, hemoglobin has a wide range of energetically accessible structures that, are related to each other by a simple sliding motion. The dimer-dimer, interface acts as a "molecular slide bearing" that allows the two alpha, beta dimers to slide back and forth without greatly altering the number or, the nature of the intersubunit contacts. Since the general stereochemical, features of this interface are not unusual, it is likely that interface, sliding of the kind displayed by fully liganded hemoglobin plays important, structural and functional roles in many other protein assemblies.

About this Structure

1G0A is a Protein complex structure of sequences from Bos taurus with and as ligands. Full crystallographic information is available from OCA.

Reference

Interface sliding as illustrated by the multiple quaternary structures of liganded hemoglobin., Mueser TC, Rogers PH, Arnone A, Biochemistry. 2000 Dec 19;39(50):15353-64. PMID:11112521

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