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Uricase: Not a typical enzyme
Christian de Duve Scientist
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I want to go back to uricase. Urate oxidase, which... it's a long time since we mentioned it so let me remind you: urate oxidase was the sixth enzyme in 1955 that we had found to show the same distribution pattern as the other five. The other five were acid hydrolysis, typical lysosomal enzymes; uricase was an oxidising enzyme, is not a digestive enzyme, it was not latent, it had a ph optimum of seven – or more than seven, maybe nine, even, if I remember rightly – and so it was an odd enzyme to be in lysosomes. And so, as we continued this work and studied additional enzymes, we found two more enzymes that showed the same kind of distribution but were not typical acid hydrolyses... hydrolases. One was D-amino-acid oxidase, which again is an oxidising enzyme like urate oxidase but oxidises amino acids... D-amino acids, not the alkaline, the unnatural, so-called D-amino acids, and like urate oxidase converts oxygen to hydrogen peroxide in doing this. And the third enzyme we discovered having the same kind of distribution was a catalase, and catalase is an enzyme that can use hydrogen peroxide to oxidise... to peroxidase substances like ethanol or nitrate... nitrite, or it can use hydrogen peroxide to oxidise hydrogen peroxide, in which case it actually splits hydrogen peroxide in H2O, water and oxygen. So the three enzymes that we had have a connection by way of hydrogen peroxide to oxidases making hydrogen peroxide, catalase destroying it.

Belgian biochemist Christian de Duve (1917-2013) was best known for his work on understanding and categorising subcellular organelles. He won the Nobel Prize in Physiology or Medicine in 1974 for his joint discovery of lysosomes, the subcellular organelles that digest macromolecules and deal with ingested bacteria.

Listeners: Peter Newmark

Peter Newmark has recently retired as Editorial Director of BioMed Central Ltd, the Open Access journal publisher. He obtained a D. Phil. from Oxford University and was originally a research biochemist at St Bartholomew's Hospital Medical School in London, but left research to become Biology Editor and then Deputy Editor of the journal Nature. He then became Managing Director of Current Biology Ltd, where he started a series of Current Opinion journals, and was founding Editor of the journal Current Biology. Subsequently he was Editorial Director for Elsevier Science London, before joining BioMed Central Ltd.

Tags: 1955

Duration: 2 minutes, 31 seconds

Date story recorded: September 2005

Date story went live: 24 January 2008