Water-mediated variability in the structure of relaxed-state haemoglobin

Kaushal, Prem Singh and Sankaranarayanan, R and Vijayan, M (2008) Water-mediated variability in the structure of relaxed-state haemoglobin. In: Acta Crystallographica Section F: Structural Biology and Crystallization Communications, 64 (6). pp. 463-469.

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Abstract

The crystal structure of high-salt horse methaemoglobin has been determined at environmental relative humidities (r.h.)of 88, 79, 75 and 66%. The molecule is in the R state in the native and the r.h. 88% crystals. At r.h. 79%, the water content of the crystal is reduced and the molecule appears to move towards the R2 state.The crystals undergo a water-mediated transformation involving a doubling of one of the unit-cell parameters and an increase in water content when the environmental humidity is further reduced to r.h. 75%. The water content is now similar to that in the native crystals and the molecules are in the R state. The crystal structure at r.h. 66% is similar, but not identical, to that at r.h. 75%, but the solvent content is substantially reduced and the molecules have a quaternary structure that is in between those corresponding to the R and R2 states. Thus,variation in hydration leads to variation in the quaternary structure.Furthermore, partial dehydration appears to shift the structure from the R state to the R2 state. This observation is in agreement with the earlier conclusion that the changes in protein structure that accompany partial dehydration are similar to those that occur during protein action.

Item Type:	Journal Article
Publication:	Acta Crystallographica Section F: Structural Biology and Crystallization Communications
Publisher:	International Union of Crystallography
Additional Information:	Copyright of this article belons to International Union of Crystallography.
Keywords:	Haemoglobin;water-mediated variability;dehydration.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	08 Jul 2008
Last Modified:	19 Sep 2010 04:47
URI:	http://eprints.iisc.ac.in/id/eprint/14830

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