JBC, Vol. 252, Issue 7, 2234-2244, Apr, 1977
Quantitative determination of carbamino adducts of alpha and beta chains in human adult hemoglobin in presence and absence of carbon monoxide and 2,3-diphosphoglycerate
J. B. Matthew, J. S. Morrow, R. J. Wittebort and F. R. Gurd
The principal component of normal adult human hemoglobin was equilibrated
under various conditions with 13CO2. Quantitative analysis of the carbamino
resonance intensities over the pH range of 6.5 to 9.0 shows that the
effects of conversion from the deoxy to the liganded state in reducing the
carbamino adduct formation occur predominantly at Val-1beta. Analysis of
the pH dependence of carbamino formation at constant total carbonates
yields values of pKz and pKc for Val-1beta and Val-1alpha in the deoxy and
liganded conditions. In contrast to the Val-1beta as the allosteric site
for CO2, the Val-1alpha site is shown to be primarily an alkaline Bohr
group. 2,3-Diphosphoglycerate is shown to reduce substantially the
Val-1beta carbamino resonance intensity in deoxyhemoglobin. Evidence for
2,3-diphosphoglycerate effects in carbon monoxide hemoglobin at both
Val-1alpha and Val-1beta sites is presented. Enhanced carbamino formation
in carbon monoxide hemoglobin at Val-1beta is observed at pH values less
than 7.8. Finally, chemical exchange analysis of the spectra shows the
release rate of the deoxy Val-1alpha carbamino adduct to be greater than
that for deoxy Val-1beta. At pH 7.47 k-1obs,beta congruent to 1.0 and
k-1obs, alpha congruent to 11.0 s-1.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?