Effects of pH, 2,3-diphosphoglycerate and salts on gelation of sickle cell deoxyhemoglobin

Robin W. Briehl, Sandra Ewert

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82 Citations (Scopus)

Abstract

Gelation of fully deoxygenated sickle cell hemoglobin was assayed by (1) determination of the temperature at which viscosity increased sharply and (2) a high-speed sedimentation equilibrium method in which three zones are seen. These are a pre-gelation zone, a narrow transition zone exhibiting aggregation, followed by a phase change and a zone of gelation. Only the first zone is seen with deoxyhemoglobin A and CO hemoglobins A and S up to about 0·35 g protein/ml. Minimal gelling temperatures by the viscosity method and, by ultracentrifugation, minimal gelling concentrations determined at the onset of aggregation and at the phase change showed: (a) lowering the pH toward 6·7 favors gelation; (b) deoxyhemoglobin S gels more readily in 6 mm-2,3-diphosphoglycerate than in its total absence; (c) 1 m-NaCl and l m-KCl inhibit gelation. The known favoring of gelation by warming is confirmed by the equilibrium method and is about 2% change in minimal gelling concentration per degree. The effects of pH and high ionic strengths are consistent with contributions of specific polar interactions to gel structure. The effect of 2,3-diphosphoglycerate probably depends on known structural changes which this cofactor induces rather than on alteration of the allosteric quaternary structure equilibrium.

Original languageEnglish (US)
JournalJournal of Molecular Biology
Volume80
Issue number3
DOIs
StatePublished - Nov 5 1973

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Sickle Hemoglobin
2,3-Diphosphoglycerate
Salts
Viscosity
Gels
Hemoglobin A
Temperature
Ultracentrifugation
Carbon Monoxide
Osmolar Concentration
sickle deoxyhemoglobin
Proteins

ASJC Scopus subject areas

  • Virology

Cite this

Effects of pH, 2,3-diphosphoglycerate and salts on gelation of sickle cell deoxyhemoglobin. / Briehl, Robin W.; Ewert, Sandra.

In: Journal of Molecular Biology, Vol. 80, No. 3, 05.11.1973.

Research output: Contribution to journalArticle

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