Guanine deaminase

Guanine deaminase (GDA) is a cytoplasmic enzyme that catalyzes the hydrolytic deamination of guanine to produce xanthine and ammonia, functioning as a key step in purine catabolism (UniProt: Q9Y2T3). This 454-amino acid protein participates in nucleotide degradation pathways and is expressed across various tissues in humans.

GDA is tagged for Alzheimer's Disease relevance in the Chaparral Knowledge Platform based on proteomics evidence. According to human post-mortem AD brain profiling using TMT-labeled quantitative proteomics across four subcellular fractions (P2, P3, S2, S3), GDA abundance is consistently down-regulated in AD brain tissue compared to age-matched controls (Chaparral AD proteomics). The mean log2 fold-change is −0.77, indicating a modest but reproducible reduction across analyzed fractions.

The functional significance of reduced guanine deaminase in AD neurodegeneration remains to be elucidated, though altered purine metabolism and nucleotide homeostasis have been implicated in neurodegenerative processes. UniProt contains no primary disease associations for this protein, suggesting that the AD-related changes are novel observations from this proteomics dataset.