IDENTIFICATION OF A NEW B-TYPE CYTOCHROME FROM THE WHITEFISH COREGONIDAE EGGS

A new b-type cytochrome, termed cytochrome b560 according to the wavel ength maximum of its alpha-band in the reduced minus oxidized differen ce spectrum, was isolated from eggs of whitefish and partially purifie d by fractionation of the water-soluble moiety of yolk. The absolute a bsorption spectrum of reduced cytochrome b560 has maxima at 426, 529 a nd 560 nm and that of the oxidized form at 416 nm. The reduced minus o xidized difference spectrum has maxima at 428, 529 and 560 nm. The mid point potential of this cytochrome is +193 mV. Based on the MCD spectr a of reduced cytochrome and the optical absorption spectra in the visi ble region of the oxidized cytochrome, it is suggested that the heme i ron in cytochrome b560 has two histidine imidazoles as the 5th and 6th axial ligands.