83 by: Bohdan Dowker

Student – Bohdan Dowker

Enzyme & EC # – Xanthine Oxidase 1.12.3.2

This enzyme plays a role in purine metabolism – breaking down nucleic acids to uric acid. Given this, it is primarily present in the liver where this metabolism takes place, however most cells in the body are capable of purine catabolism.

Xanthine oxidase, along with several other cofactors, catalyzes the breakdown of hypoxanthine to xanthine to uric acid in purine metabolism. The enzyme itself orients the substrate and lowers the activation energy of the reaction. Meanwhile the molybdenum coenzyme is more involved in the reaction mechanism, or the transfer of electrons.

In natural settings, the mechanism regenerates the FAD electron carrier using NAD+, while in lab settings the enzyme can use molecular oxygen (which forms hydrogen peroxide).

References

Aziz N, Jamil R. (2023) Biochemistry, Xanthine Oxidase. National Library of Medicine; [cited 2024 October 17]. Available from https://www.ncbi.nlm.nih.gov/books/NBK545245/

Catalyst University. (2015). Biochemistry | Purine Metabolism [Conversion of Hypoxanthine to Uric Acid]. Youtube; [cited 2024 October 17]. Available from https://www.youtube.com/watch?v=kG4CoTxN3Us&list=LL&index=4&t=161s

EMBL-EBI. (2024) Xanthine Oxidase. Mechanism and Catalytic Site Atlas. EMBL-EBI; [cited 2024 October 17]. Available from https://www.ebi.ac.uk/thornton-srv/m-csa/entry/987/

Pedley A, Benkovic S. (2030) A New View into the Regulation of Purine Metabolism: The Purinosome. Science Direct; [cited 2024 October 17]. Available from

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/purine-meta

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