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Biomedical subjects

C Ho

Publications and source records attributed to C Ho.

At least 289 records · Page 16Linked to original sources
PubMed1973

Statistical mechanics applied to cooperative ligand binding to proteins.

By using the lattice statistical argument, we have shown that for a protein whose subunits have the same number of neighbors, the three parameters (K(AB), K(BB), and K(S)K(t)) in the sequential theory formulated by Koshland, Nemethy, and Filmer [Biochemistry (1966) 5, 365] can be reduced to two parameters. One of the parameters, Z, measures the strength of the subunit interactions and is related to the apparent free energy of interaction (DeltaF degrees I) by Z = exp (-DeltaF degrees I/2mkT), where m is the number of neighbors in a subunit and kT has the usual meaning. In addition, we relate Wyman's allosteric binding potential [Advan. Protein Chem. (1964) 19, 223] to the canonical partition function of the McMillan-Mayer theory [J. Chem. Phys. (1945) 13, 276]. An explicit form relating the apparent free energy of interaction and the Hill coefficient is given for an allosteric protein that has nonequivalent and independent ligand-binding sites. The present formulation can be used to account for a number of recent experimental results on hemoglobins.

Binding Sites↗
PubMed1973

Direct measurement of the pK values of an alkaline Bohr group in human hemoglobin.

Proton nuclear magnetic resonance spectra of normal and des-(his 146beta) human hemoglobin in the aromatic resonance region have been compared at different pH values. From these measurements, a pK value for histidine 146beta of 7.1 in carbonmonoxyhemoglobin and 8.0 in deoxyhemoglobin has been found. These pK values confirm the proposed role of histidine 146beta in the alkaline Bohr effect.

Carboxyhemoglobin↗
PubMed1972

Functional nonequivalence of and hemes in human adult hemoglobin.

Nuclear magnetic resonance studies of the contact-shifted spectra of heme protons in deoxyhemoglobin A from human adults show conclusively that oxygen binds to the alpha hemes in preference to the beta hemes. The preferential binding is produced in 10% hemoglobin solution at neutral pH by either a 15-fold molar excess of 2,3-diphosphoglycerate or a 5-fold molar excess of inositol hexaphosphate. Preferential binding is not observable in the absence of the organic phosphates. The results indicate that the oxygenation of hemoglobin may be described by a sequential model, or by a concerted model that allows the alpha hemes to bind ligand first.

Adult↗