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emoglobin-bound CO2 was estimated by a procedure first described by Rossi-Bernardi et al. (1969) in which the carbamate compound is stabilized by rapid mixing with alkali and then separated from other CO2 constituents in solution by gel filtration and ion-exchange chromatography. Carbamate equilibrium of bovine hemoglobin was studied at constant PCO2 (44 mm Hg) and varying pH as well as at constant pH (7.4) and varying PCO2 (ionic strength 0.18, temperature 37.0 degrees C). The difference in Z (deltaZ) between hemoglobin and oxyhemoglobin appeared to be 0.11 plus or minus 0.04 (pH=7.40; PCO2=44 mm Hg) i.e. about half the value observed in human hemoglobin. DeltaZ was shown to account completely for the difference in CO2 content (CCO2) between hemoglobin and oxyhemoglobin when in total equilibrium with CO2. Carbamate determinations on bovine hemoglobin specifically modified at all terminal amino groups (double-blocked carbamylated derivative) did not show any CO2 binding at all, thus giving a final proof for the exclusive role of the terminal amino groups in CO2 binding under physiological conditions. Attempts to calculate the ionization constant (Kz) and the carbamate equilibrium constant (Kc) of the terminal amino groups failed, suggesting that both terminal groups are not equivalent in their CO2 binding properties. This was confirmed by the fact that carbamate data obtained at constant PCO2 and varying pH fitted binding curves derived from two sets of independent but non-equivalent binding sites. Association constants for both kinds of binding sites appeared to differ by a factor of at least 3 in hemoglobin and of about 10 in oxyhemoglobin. From determinations of hemoglobin-bound CO2 and CO2 content of hemoglobin and oxyhemoglobin solutions in total equilibrium with CO2, the apparent first dissociation constant of carbonic acid was calculated as 5.71 plus or minus 0.0061 pH and found to be independent of the oxygenation state of hemoglobin. In contrast with hemoglobin of other species bovine hemoglobin appeared to be not influenced by the presence of 2.3-diphosphoglycerate as far as its CO2-binding properties are concerned.
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
June 1981,
The Journal of biological chemistry,
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
November 1975,
The Journal of pharmacy and pharmacology,
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
October 1972,
Journal de physiologie,
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
March 1980,
Thrombosis research,
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
April 1986,
Zentralblatt fur Bakteriologie, Mikrobiologie und Hygiene. Serie B, Umwelthygiene, Krankenhaushygiene, Arbeitshygiene, praventive Medizin,
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
April 1988,
The Journal of hospital infection,
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
January 1979,
Research in veterinary science,
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
October 2007,
Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases,
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
October 1974,
Hoppe-Seyler's Zeitschrift fur physiologische Chemie,
L H Van Kempen, and
P M Breepoel, and
F Kreuzer
June 1964,
Science (New York, N.Y.),
