Double mixing stopped-flow method for the study of equilibria and kinetics of dimer-tetramer association of hemoglobins: studies on Hb Carp, Hb A, and Hb Rothschild.
A double mixing stopped-flow method is described for studying the dimer-tetramer equilibria of oxyhemoglobins and the kinetics of association of unliganded dimers. The three hemoglobins studied were: Hb Carp, Hb A, and Hb Rothschild (Trp beta 37 (C3)----Arg). The new method reproduces the data obtained for oxyHb A by other established methods. In agreement with previous studies, the new method indicates little, if any, dissociation of oxyHb carp into dimers even in 2 M urea solutions (0.1 M Bis-Tris pH 7.0). OxyHb Rothschild, on the other hand, is extensively dissociated into dimers (K(Hb4L4 in equilibrium with 2Hb2) = 37.3 x 10(-6) M) and the rate constant for the association of deoxy dimers of Hb Rothschild is about one-tenth of the value for Hb A indicating that the deoxy tetramer of Hb Rothschild is at least 10 times more dissociated into dimers than deoxyHb A.
Berjis
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M
Department of Medicine, University of California, San Diego, La Jolla 02093.
Sharma
V S
VS
D000818:Animals; D002347:Carps; D002623:Chemistry Techniques, Analytical / Q000379:methods; D006441:Hemoglobin A / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry*; D006455:Hemoglobins, Abnormal / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D010108:Oxyhemoglobins / Q000737:chemistry*; D013329:Structure-Activity Relationship
D006454:Hemoglobins; D006455:Hemoglobins, Abnormal; D046911:Macromolecular Substances; D010108:Oxyhemoglobins; C024993:hemoglobin Rothschild; D006441:Hemoglobin A; C029774:oxyhemoglobin A