Subunit Interactions of Glucose‐6‐Phosphate Dehydrogenase from Human Erythrocytes

P. Cohen, M. A. Rosemeyer

Research output: Contribution to journalArticle

87 Citations (Scopus)

Abstract

Glucose‐6‐phosphate dehydrogenase from human erythrocytes shows successive aggregation‐dissociation equilibria. The effects of salt concentration and pH show that a molecule of 210,000 molecular weight and s20,w of 9.0 S dissociated to a half‐molecule of 105,000 molecular weight and s20,w of 5.6 S. Evidence for this being a discrete dissociation was provided by molecular weight determinations, relation between sedimentation coefficients and molecular weights, and the occurrence of skew patterns at a particular degree of dissociation. Some aggregation of the molecule to give apparent molecular weights above 210,000 occurred at low salt concentrations in the pH range 6–7. Reaction with maleic anhydride gave a species of molecular weight 53,000 and s20,w 3.4 S, indicating that in the native protein the predominant molecular species (210,000) was a tetramer. The nature of the dissociations indicate the dissimilarities between the subunit contacts in the tetrameric molecule. Optimum conditions for the enzyme assay suggest that the dimer contains the essential requirements for the catalytic function of the protein, and the implications of these findings are discussed.

Original languageEnglish
Pages (from-to)8-15
Number of pages8
JournalEuropean Journal of Biochemistry
Volume8
Issue number1
DOIs
Publication statusPublished - Mar 1969

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Oxidoreductases
Erythrocytes
Molecular Weight
Molecular weight
Molecules
Salts
Maleic Anhydrides
Enzyme Assays
Sedimentation
Dimers
Assays
Proteins
Agglomeration
Enzymes

Cite this

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abstract = "Glucose‐6‐phosphate dehydrogenase from human erythrocytes shows successive aggregation‐dissociation equilibria. The effects of salt concentration and pH show that a molecule of 210,000 molecular weight and s20,w of 9.0 S dissociated to a half‐molecule of 105,000 molecular weight and s20,w of 5.6 S. Evidence for this being a discrete dissociation was provided by molecular weight determinations, relation between sedimentation coefficients and molecular weights, and the occurrence of skew patterns at a particular degree of dissociation. Some aggregation of the molecule to give apparent molecular weights above 210,000 occurred at low salt concentrations in the pH range 6–7. Reaction with maleic anhydride gave a species of molecular weight 53,000 and s20,w 3.4 S, indicating that in the native protein the predominant molecular species (210,000) was a tetramer. The nature of the dissociations indicate the dissimilarities between the subunit contacts in the tetrameric molecule. Optimum conditions for the enzyme assay suggest that the dimer contains the essential requirements for the catalytic function of the protein, and the implications of these findings are discussed.",
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Subunit Interactions of Glucose‐6‐Phosphate Dehydrogenase from Human Erythrocytes. / Cohen, P.; Rosemeyer, M. A.

In: European Journal of Biochemistry, Vol. 8, No. 1, 03.1969, p. 8-15.

Research output: Contribution to journalArticle

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AB - Glucose‐6‐phosphate dehydrogenase from human erythrocytes shows successive aggregation‐dissociation equilibria. The effects of salt concentration and pH show that a molecule of 210,000 molecular weight and s20,w of 9.0 S dissociated to a half‐molecule of 105,000 molecular weight and s20,w of 5.6 S. Evidence for this being a discrete dissociation was provided by molecular weight determinations, relation between sedimentation coefficients and molecular weights, and the occurrence of skew patterns at a particular degree of dissociation. Some aggregation of the molecule to give apparent molecular weights above 210,000 occurred at low salt concentrations in the pH range 6–7. Reaction with maleic anhydride gave a species of molecular weight 53,000 and s20,w 3.4 S, indicating that in the native protein the predominant molecular species (210,000) was a tetramer. The nature of the dissociations indicate the dissimilarities between the subunit contacts in the tetrameric molecule. Optimum conditions for the enzyme assay suggest that the dimer contains the essential requirements for the catalytic function of the protein, and the implications of these findings are discussed.

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