Coupled oxidation of ascorbic acid and haemoglobin

IN this paper we describe a spectrophotometric method allowing us to measure quantitatively the destruction of haemoglobin and the formation of choleglobin and cholehaemochromogen during the coupled oxidation of haemoglobin with ascorbic acid and with other reducing substances. The influence of various factors, the nature of the reactants, pH, temperature and oxygen pressure, on the velocity of the reaction is studied. The 'oxidation of ascorbic acid during the reactions is measured in the usual way by indicator titration, and the ratio of molecules of ascorbic acid oxidized to molecules of choleglobin formed is thus found. The spectrophotometric determination method enables us, also, quantitatively to correlate the formation of choleglobin with the increase of 'labile iron' andwith the yield of bile pigments to be obtained after acid splitting, thus giving us a much more complete insight into the reaction; the results of these studies are described in Parts 4 and 5.