“…Aliquots of flavocytochrome b, or of the isolated xT, q or FDH,, fragments, stored in cold lactate-containing buffer, were introduced under gentle stirring to a 1 pM solution of the Hunsenula anornala Zn-cytochrome c dimer [7] in 10mM phosphate, 10 mM DL-lactate buffer at 10 ' C , directly in a semimicro cuvette placed in the sample compartment of the fluorimeter. The buffer contained enough lactate to ensure complete reduction of the prosthetic groups in the FDH,., tetramer as well as in flavocytochrome b,.…”