Variation of quadrupole splitting in modified oxyhemoglobin: A Mossbauer effect study

Human adult hemoglobin modified by both pyridoxal-5'-phosphate and glutaral dehyde in the oxy-form was studied by Mossbauer spectroscopy. Mossbauer spe ctra were measured at 87 and 295 K (hemoglobin in lyophilized form) and at 87 K (hemoglobin in frozen solution). The values of the quadrupole splittin g for modified oxyhemoglobin were found to be lower then those of oxyhemogl obin without modifications in lyophilized form and frozen solution, respect ively. The Mossbauer spectra of modified oxyhemoglobin were also analyzed i n terms of the heme iron inequivalence in alpha- and beta-subunits of the t etramer. Differences of the tendencies of temperature dependencies of quadr upole splitting for modified and non-modified oxyhemoglobin in lyophilized form were shown.