Proton-linked subunit kinetic heterogeneity for carbon monoxide binding to hemoglobin from Chelidonichthys kumu.

The Journal of Biological Chemistry
M ColettaG di Prisco

Abstract

The pH dependence of CO binding kinetics to Chelidonichthys kumu hemoglobin (Hb) and human adult Hb has been investigated between pH 2.0 and 9.0 at 20 degrees C. For both Hbs, CO binding kinetics is characterized by two proton-linked transitions, with different pKa values for alpha- and beta-chains in C. kumu Hb, leading to a relevant functional kinetic heterogeneity at most pH values. On the other hand, in human adult Hb the CO binding does not display a functional heterogeneity. Lowering the pH from 9 to 6 brings about a decrease of the CO binding rate constants, to a different extent for human adult Hb and the two chains of C. kumu Hb. Further lowering the pH from 6 to 2 induces an enhancement of CO binding rate constants, probably related to the protonation of proximal HisF8 Nepsilon atom and the cleavage (or severe weakening) of the HisF8-Fe bond. The presence of physiological concentrations of ATP (approximately 3 mM) affects the pH dependence of CO binding kinetics to C. kumu. Moreover, the effect of temperature (between 8 degrees C and 38 degrees C) on CO binding kinetics has been investigated in the absence of ATP at different pH values. These results allow to interpret the functional kinetic heterogeneity of C. kumu H...Continue Reading

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Citations

Sep 21, 2004·Journal of Biological Inorganic Chemistry : JBIC : a Publication of the Society of Biological Inorganic Chemistry·Mauro FasanoPaolo Ascenzi
Apr 19, 2005·Journal of Inorganic Biochemistry·Paolo AscenziMassimo Coletta
Oct 4, 2007·Biochemical and Biophysical Research Communications·Paolo AscenziMassimo Coletta
Jul 16, 2002·The Journal of Biological Chemistry·Cinzia VerdeGuido Di Prisco
May 24, 2006·The Journal of Biological Chemistry·Cinzia VerdeGuido di Prisco
Feb 11, 2021·International Journal of Molecular Sciences·Giovanna De SimonePaolo Ascenzi

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