[Acid-base equilibrium of yellow lupine ferrileghemoglobin. potentiometric studies]

Dissociation of ionizing groups in leghemoglobin from Lupinus Luteus in the wide pH range was studied by potentiometric titration. 16 + 8 groups were shown to the titrated at acid pH. One part of them are normally titrating groups and the other one is associated with some details of protein structure. At neutral pH 4 groups are titrated, the titration of 3 of the show histeresis. Five lysins are normally titrated at the alkaline pH. among them one is possibly responsible for an alkaline dissociation. 13 charged groups take part in the dissociation, 3-4 are titrated inreversibly. The experimental results are analyzed in terms of Linderstrom-Lang-Tanford representation and are discussed on the basis of primary and three-dimentional leghemoglobin structure.