Abstract
Hemoglobin and solubilized Heinz bodies whose heme moiety had been labeled with C14, and C14-hemin were infused into rats with an external bile fistula. The fractional conversion of these heme pigments to bilirubin was estimated from the amount of C14-bilirubin excreted in the bile.
Whereas a major fraction of the native hemoglobin and intact hemin was converted to bilirubin, the heme moiety of the Heinz bodies was broken down to diazo- and benzidine-negative, water- and butanol-soluble metabolites which were excreted in the bile and, to a lesser extent, in the urine. These excretory products had the solubility and spectroscopic properties of mesobilifuscins, but their exact chemical configuration could not be determined.
The findings indicate that oxidative denaturation of hemoglobin is associated with structural alterations of the heme moiety that favor its catabolism by a pathway in which bilirubin is neither an intermediate nor an end product. The significance of this alternate metabolic pathway for the overall turnover of hemoglobin and other heme proteins is discussed.
