The hemoglobin binding and activation by haptoglobins: Spectrophotometric and potentiometric measurements

Abstract

Haptoglobins (Hp) are known to bind Hemoglobin (Hb). This binding implies a considerable increase of the peroxydase activity of Hemoglobin (Polonovski et Jayne 1938). The binding site of Hp on Hb is located on the globin moiety (Van Royen 1950, Nyman 1959), although the increased peroxydase activity of Hb is related to the configuration of the haem group. In this study evidence has been obtained that the carbomonoxy-hemoglobin-haptoglobin association is accompanied by: 1. 1) Spectral modifications of HbCO in the visible range, which are related to the binding of HbCO with Hp: presence of charge transfer bands (CTB) characteristic of high spin derivatives (Brill and Williams 1961). 2. 2) Release of protons H + measured during the association, which is closely related to the activating ability of Hp.