Fluorescence studies on the binding of reduced nicotinamide adenine dinucleotide phosphate to human hemoglobin A and its variant hemoglobin Providence.
Year: 1987
Type: article
Abstract: The affinity constants for the binding of NADPH to human hemoglobin A were directly determined by fluorescence analysis since nucleotide fluorescence is quenched on binding to the protein. The binding constants 6.1 x 10(5), 5.02 x 10(5) and 1.2 x 10(5) were found for deoxyhemoglobin at pH 6.5, 7.0 and 7.5, respectively. Oxyhemoglobin does not bind NADPH significantly. These results are consistent with those found in oxygen-hemoglobin equilibrium experiments. The human hemoglobin variant, Providence-Asp, which has a marked decrease in 2,3 DPG affinity was also investigated. NADPH does not bind to the variant suggesting that the Lys B 82 residue is of fundamental importance to nucleotide binding and showing that the binding site is the same as that of 2,3 DPG or other organic polyphosphate, allosteric modulators of hemoglobins. Experiments of inositol hexaphosphate (IHP)-NADPH site competition corroborate these results.
Source: PubMed
Institution: Universidade Estadual de Campinas (UNICAMP)
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2359340198