A comparative study on the structural differences of primate hemoglobins by spin labeling technique.

The hemoglobins of human and five non-human primates were spin-labeled with N-(1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl)iodoacetamide, and the ESR spectra of their deoxy, oxy, and carbonmonoxy forms were measured. The analyses of the spectra indicated that the local protein conformation in the vicinity of the spin-labeled cysteine residue at position 93(F9) in the beta-chain is slightly but significantly different among species, and that each hemoglobin shows a similar change in conformation upon conversion from the oxy form to the carbonmonoxy one except for human hemoglobin. Human hemoglobin was suggested to undergo a significantly different conformational change upon this conversion, indicating that it has unique characteristics among the primate hemoglobins.