抄録
N-l-Oxyl-2, 2, 6, 6-tetramethyl-4-piperidinyl-iodoacetamide spin-labeled human adult hemoglobin has been combined with O2, CO, and various nitrosobenzene derivatives and its electron paramagnetic resonance spectrum has been measured at different temperatures. Compared with those of O2- and CO-liganded form, the weakly immobilized signal of the hemoglobin liganded with nitrosobenzene derivatives was narrow and, moreover, the intensity of the signal relative to that of the strongly immobilized one was low in the perfluoro-nitrosobenzene-liganded hemoglobin. This indicates that the conformation of hemoglobin near the label binding site depends upon the size of ligands attached to hemes. The ligand-size dependent conformational difference cannot be observed if the iodoacetamide group in the label is replaced by ethylmaleimide.
