New Sequential Model for Human Hemoglobin: Alpha Subunit as Cooperativity Inducer
Abstract:
Hemoglobin is a tetrameric oxygen transport protein in animal bodies. However, there is a paucity of information regarding differences between alpha and beta subunits of hemoglobin in terms of oxygen affinity. The sequential model of Koshland, Nemthy and Filmer (KNF model) has attributed similar affinities to both alpha and beta subunits. The main purpose of the present study is to construct a new sequential model for hemoglobin oxygenation based on higher oxygen affinities for alpha subunits. To this end, coordinate files of 19 oxy and 41 deoxy hemoglobin structures were used as starting structures. These files were processed using Microsoft Excel and SPSS software in order to calculate Euclidean distances between each pair of proximal and distal histidine Fe2 as well as other pairs of atoms of interest. The calculated distances were then compared for either set of hemoglobin conformations, i.e. oxy and deoxy conformations. Our results showed that α2 subunit show higher structural changes that could be related to oxygen affinity. This subunit could be introduced as initiator of hemoglobin oxygenation and cooperativity. Subunit α2 in our sequential model induces relaxed conformation in α1, β2 and β1 respectively. The order of oxygen affinity in our model is as follow: α2 > α1 > β1 > β2.
Language:
English
Published:
Biomacromolecular Journal, Volume:1 Issue: 2, Autumn 2015
Pages:
148 to 153
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