Abstract
The populations of the intermediates in concentrated solutions of hemoglobin A0 equilibrated at various PCO values, pH 7.0, 0.1 M KCl, and 20 ° C, have been determined using cryogenic methods. Data on CO saturations and distributions of intermediates were analysed in terms of the free energies of dimer-tetramer assembly of the intermediates (G.K. Ackers and F.R. Smith, Annu. Rev. Biophys. Chem. 16 (1987) 583). The cooperative free energy value of the singly ligated species was approximately one-half the total cooperative energy. The cooperative free energy value of the doubly ligated species was not significantly different from that of carboxyhemoglobin. Because of experimental error, the observed difference in concentrations among the populations of the doubly ligated species cannot be taken as indicative of their functional heterogeneity. Additional studies on some NO intermediates have emphasized that (α1β1)(α2β2)X, a key intermediate in the formulation of the 'third-state' hypothesis in the deoxy/cyanomethemoglobin system, has a free energy value for dimer-tetramer assembly which is critically dependent on the nature of the ligand X as suggested by Ackers and Smith (reference as cited above).
| Original language | English |
|---|---|
| Pages (from-to) | 211-223 |
| Number of pages | 13 |
| Journal | Biophysical Chemistry |
| Volume | 37 |
| Issue number | 1-3 |
| DOIs | |
| Publication status | Published - Aug 31 1990 |
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Keywords
- Allosterism
- Cryogenics
- Hemoglobin intermediate
ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Physical and Theoretical Chemistry
Cite this
What the intermediate compounds in ligand binding to hemoglobin tell about the mechanism of cooperativity. / Perrella, Michele; Colosimo, Alfredo; Benazzi, Louise; Ripamonti, Marilena; Rossi-Bernardi, Luigi.
In: Biophysical Chemistry, Vol. 37, No. 1-3, 31.08.1990, p. 211-223.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - What the intermediate compounds in ligand binding to hemoglobin tell about the mechanism of cooperativity
AU - Perrella, Michele
AU - Colosimo, Alfredo
AU - Benazzi, Louise
AU - Ripamonti, Marilena
AU - Rossi-Bernardi, Luigi
PY - 1990/8/31
Y1 - 1990/8/31
N2 - The populations of the intermediates in concentrated solutions of hemoglobin A0 equilibrated at various PCO values, pH 7.0, 0.1 M KCl, and 20 ° C, have been determined using cryogenic methods. Data on CO saturations and distributions of intermediates were analysed in terms of the free energies of dimer-tetramer assembly of the intermediates (G.K. Ackers and F.R. Smith, Annu. Rev. Biophys. Chem. 16 (1987) 583). The cooperative free energy value of the singly ligated species was approximately one-half the total cooperative energy. The cooperative free energy value of the doubly ligated species was not significantly different from that of carboxyhemoglobin. Because of experimental error, the observed difference in concentrations among the populations of the doubly ligated species cannot be taken as indicative of their functional heterogeneity. Additional studies on some NO intermediates have emphasized that (α1β1)(α2β2)X, a key intermediate in the formulation of the 'third-state' hypothesis in the deoxy/cyanomethemoglobin system, has a free energy value for dimer-tetramer assembly which is critically dependent on the nature of the ligand X as suggested by Ackers and Smith (reference as cited above).
AB - The populations of the intermediates in concentrated solutions of hemoglobin A0 equilibrated at various PCO values, pH 7.0, 0.1 M KCl, and 20 ° C, have been determined using cryogenic methods. Data on CO saturations and distributions of intermediates were analysed in terms of the free energies of dimer-tetramer assembly of the intermediates (G.K. Ackers and F.R. Smith, Annu. Rev. Biophys. Chem. 16 (1987) 583). The cooperative free energy value of the singly ligated species was approximately one-half the total cooperative energy. The cooperative free energy value of the doubly ligated species was not significantly different from that of carboxyhemoglobin. Because of experimental error, the observed difference in concentrations among the populations of the doubly ligated species cannot be taken as indicative of their functional heterogeneity. Additional studies on some NO intermediates have emphasized that (α1β1)(α2β2)X, a key intermediate in the formulation of the 'third-state' hypothesis in the deoxy/cyanomethemoglobin system, has a free energy value for dimer-tetramer assembly which is critically dependent on the nature of the ligand X as suggested by Ackers and Smith (reference as cited above).
KW - Allosterism
KW - Cryogenics
KW - Hemoglobin intermediate
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U2 - 10.1016/0301-4622(90)88020-S
DO - 10.1016/0301-4622(90)88020-S
M3 - Article
C2 - 2285782
AN - SCOPUS:0025072785
VL - 37
SP - 211
EP - 223
JO - Biophysical Chemistry
JF - Biophysical Chemistry
SN - 0301-4622
IS - 1-3
ER -