Open AccessThe Effect of pH and d ‐Glycerate 2,3‐Bisphosphate on the O 2 Equilibrium of Norma1 and SH(β93)‐Modified Human Hemoglobin
Author(s) -
ANTONINI Eraldo,
CONDÒ Saverio G.,
GIARDINA Bruno,
IOPPOLO Carmela,
BERTOLLINI Albcrto
Publication year - 1982
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1982.tb05789.x
Subject(s) - bohr effect , hemoglobin , chemistry , phosphate , oxygen , p50 , stereochemistry , biochemistry , organic chemistry , oxygen–haemoglobin dissociation curve , transcription factor , gene
The present paper reports data for the effect of pH and d ‐glycerate 2,3‐bisphosphate ( d ‐glycerate‐2,3‐ P 2 ) on the oxygen equilibrium of norma1 and SH(β93)‐modified human hemoglobin. At sufficiently high d ‐glycerate‐2,3‐ P 2 concentrations, both oxy and deoxy forms of HbA are saturated with the organic phosphate at a1l pH va1ues between 6 and 9. Furthermore the difference in the affinity for d ‐glycerate‐2,3‐ P 2 between deoxy and oxy hemoglobin remains constant with pH, implying that the p K va1ues of the Bohr effect groups in deoxy and oxyhemoglobin are not affected by the presence of d ‐glycerate‐2,3‐ P 2 on the hemoglobin molecule. In the hemoglobins modified in position β93, the difference in affinity between deoxy and oxy hemoglobin for d ‐glycerate‐2,3‐ P 2 decreases with decrease in pH due mainly to a decrease in the affinity of the deoxy form for d ‐glycerate‐2,3‐ P 2 . The effect of the chemica1 modification appears to be primarily a change in p K of a Bohr group in deoxy hemoglobin which is especia1ly pronounced in the presence of phosphates.