Urinary excretion of isomers of biliverdin after destruction in vivo of haemoproteins and haemin

Abstract

The amount and isomeric composition of urinary biliverdin in rabbits were analysed by h.p.l.c. Physiological values were maintained after the injection of haemin. On the other hand, when haemoglobins from several mammalian species were injected into rabbits, the excretion of biliverdin-IX alpha and biliverdin-IX beta were increased 6-18-fold and 32-66-fold respectively over physiological excretion. Injection of myoglobin resulted in a 44-fold increase in excretion of the IX alpha-isomer. Coupled oxidation with ascorbate of haemoglobin and myoglobin by oxygen produced mainly the IX alpha- and IX beta-isomers from haemoglobin and the IX alpha-isomer from myoglobin. The destruction of part of the haem from injected haemoproteins by non-enzymic chemical degradation would account for the observed respective increases in the excretion of biliverdin isomers. The excretion of biliverdin isomers after the injection of phenylhydrazine into rabbits was similar to that after the injection of haemoglobin.

Unconjugated bilirubin induces apoptosis in colon cancer cells by triggering mitochondrial depolarization

“…In some nonmammalian vertebrates (e.g., birds, reptiles, amphibians), heme degradation terminates at the heme oxygenase step, 1 with the biliverdin end product efficiently eliminated in the bile and urine. 2,3 The evolutionary development of the energetically costly process of bilirubin production and elimination suggests that this bile pigment may serve an important physiologic function.…”

Effects of the arrangement of a distal histidine on regioselectivity of the coupled oxidation of sperm whale myoglobin mutants

“…2(b)]. 8 Elimination of the distal histidine does not alter the major product [Fig. 2(c)]; however, a small amount of the g-isomer, which is absent in the case of wild type Mb, is observed presumably because the replacement of His-64 with a smaller residue such as Leu allows the bound oxygen to be directed toward the g-meso position (Fig.…”

The in vivo and in vitro oxidation of molecular form 1 of biliverdin reductase to molecular form 3 by diamide

“…Phenylhydrazine in the presence of oxygen is known to degrade hemoproteins by chemical attack, and it is also known that the chemical oxidation of hemoglobin results mainly in the formation of biliverdins I& and IX@ [20]. The increased excretion of bilirubin IX,8 found under conditions of oxidative stress [21] falls in line with the need for an increased reduction rate of biliverdin 1X,8. The results reported in this paper suggest that an in vivo formed diazene will lead to the formation in the liver of a form of biliverdin reductase which will be less susceptible to or&dative attack, while at the same time it will reduce more efficiently the ,& isomer of biliverdin.…”