Effect of carbamidomethylation of cysteine residues G11(104)α on the properties of hemoglobin A
Copyright policy )Effect of carbamidomethylation of cysteine residues G11(104)α on the properties of hemoglobin A
A modified hemoglobin tetramer has been prepared containing carbamidomethylated G11(104)alpha cysteine residues. The molecule is electrophoretically identical to hemoglobin A, at pH 8.6, contains 2 titratable sulfhydryl groups per tetramer, and shows a normal oxygen affinity at half-saturation. However, the cooperative oxygen binding is significantly decreased. As the G11(104)alpha cysteine residues are located at the alpha1beta1 contact point in the hemoglobin tetramer, the results of this study indicate that modification within this portion of the molecule does not interfere with the assembly of subunits to form a tetramer or the resultant p50 but can cause a significant alteration of cooperative oxygen binding. In addition, spin-labels attached to this cysteine residue are not sensitive to changes in conformation which may take place at this contact point during oxygen binding. It is therefore possible that modification of the G11(104)alpha cysteine residue abolishes the contribution of the alpha1beta1 contact point to the cooperative oxygen binding phenomenon.
- University of Texas Health Science Center at Dallas United States
- The University of Texas System United States
Binding Sites, Macromolecular Substances, Protein Conformation, Electron Spin Resonance Spectroscopy, Electrophoresis, Disc, Iodoacetamide, Oxygen, Hemoglobins, Oxyhemoglobins, Humans, Cysteine, Protein Binding
Binding Sites, Macromolecular Substances, Protein Conformation, Electron Spin Resonance Spectroscopy, Electrophoresis, Disc, Iodoacetamide, Oxygen, Hemoglobins, Oxyhemoglobins, Humans, Cysteine, Protein Binding
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