Hydrogen-tritium exchange survey of allosteric effects in hemoglobin
The oxy and deoxy forms of hemoglobin display major differences in H-exchange behavior. Hydrogen-tritium exchange experiments on hemoglobin were performed in the low-resolution mode to observe the dependence of these differences on pH (Bohr effect), organic phosphates, and salt. Unlike a prior report, increasing pH was found to decrease the oxy-deoxy difference monotonically, in general accordance with the alkaline Bohr effect. A prior report that the H-exchange difference between oxy- and deoxyhemoglobin vanishes at pH 9, and thus appears to reflect the Bohr effect alone, was found to be due to the borate buffer used, which at high pH tends to abolish the oxy-deoxy difference in a limited region of the H-exchange curve. Effects on hemoglobin H exchange due to organic phosphates parallel the differential binding of these agents (inositol hexaphosphate more than diphosphoglycerate, deoxy more than oxy, at low pH more than at high pH). Added salt slows H exchange of deoxyhemoglobin and has no effect on the oxy form. These results display the sensitivity of simple H-exchange measurements for finding and characterizing effects on structure and dynamics that may occur anywhere in the protein and help to define conditions for higher resolution approaches that can localize the changes observed.
- Research Organization:
- Univ. of Pennsylvania, Philadelphia
- OSTI ID:
- 6278151
- Journal Information:
- Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:7; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
Similar Records
A proton nuclear magnetic resonance investigation of the anion Bohr effect of human normal adult hemoglobin
A proton nuclear magnetic resonance investigation of proximal histidyl residues in human normal and abnormal hemoglobins: a probe for the heme pocket
Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
BORATES
BORON COMPOUNDS
CARBOXYLIC ACIDS
ELEMENTS
GLOBIN
HEMOGLOBIN
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN
ION EXCHANGE
KINETICS
LABELLED COMPOUNDS
METHEMOGLOBIN
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PH VALUE
PHOSPHATES
PHOSPHORUS COMPOUNDS
PIGMENTS
PORPHYRINS
PROTEINS
REACTION KINETICS
TRITIUM COMPOUNDS