Inactivation of digestive proteases by deconjugated bilirubin: the possible evolutionary driving force for bilirubin or biliverdin predominance in animals.

摘要

In humans and some other animals, bilirubin is excreted as the end product of haem originating from haemoglobin and other hae-moproteins, and it has been the cause of jaundice and kemicterus.12 The conversion of haem to bilirubin is a two-step process.1 First, haem is converted to biiiverdin by haem oxygenase. Then biiiverdin is converted to bilirubin by biiiverdin reductase. Interestingly, many animals take biiiverdin as the end product of haem, without converting it further to bilirubin.2 Biiiverdin is water soluble and readily excreted through bile or urine.