- Nucleotidase converts AMP to adenosine
- Adenosine deaminase converts adenosine to inosine and free ammonium
- Nucleotide phosphorylase converts inosine to hypoxanthine
- Xanthine oxidase converts hypoxanthine to xanthine
> Introduces a keto group

> Xanthine is a common intermediate in the breakdown of GMP and AMP

> Xanthine oxidase introduces another ketone group in hypoxanthine to make xanthine

- Xanthine oxidase converts xanthine into uric acid and H2O2
> Adds another ketone group

- Uric acid is deprotonated under physiological conditions to be urate
> This is where it stops for humans, birds, and reptiles

> We’ve lost the uricase gene so we can’t do urate -> allantoin

- Uric acid can be broken down in 2 steps to be allantoin (uricase)
> Can be released in urine by ~squirrels~

> Further catabolism can lead to NH3 ~fish~


AMP Catabolism

- Overall:
- Convert AMP and GMP to Xanthine
- Eliminate Xanthine as Urate
- AMP Specific Process


Michigan State University

- The breakdown of nucleotides relies on three major classes of enzymes
- Nucleotidases: Convert nucleotides to nucleosides by removing a phosphate group
- Nucleoside phosphorylases: Nucleoside to a free base and ribose 1-P
- Phosphoribomutase (isomerization): Ribose 1-P to ribose 5-P
> Ribose 5-P can be recycled to make more nucleotides


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