Conformation of bovine nitrosylhemoglobins: an ESR study

The structural properties of nitrosylhemoglobins from two bovine species, namely cow and buffalo, have been investigated using electron spin resonance spectroscopy. Bovine hemoglobins show sensitivity to the presence of chloride ions and organic phosphates. ESR spectral features indicate a stable deoxy quaternary conformation of the molecule when compared to normal adult human hemoglobin A. Amino acid substitutions at the amino terminal end of the beta chain and at other sites of the alpha and beta chains seems to shift the allosteric equilibrium towards the T state in bovine hemoglobins. The results also confirm the intrinsically low oxygen affinity of bovine hemoglobins under physiological conditions.