Catalase

Catalase (CAT) is a 527-amino acid peroxisomal oxidoreductase that catalyzes the degradation of hydrogen peroxide to water and oxygen, protecting cells from oxidative damage (UniProt: P04040). The enzyme also promotes growth of diverse cell types including lymphocytes and fibroblasts. Loss-of-function mutations cause acatalasemia (ACATLAS), an autosomal recessive metabolic disorder marked by severely reduced catalase activity and oral ulceration.

Catalase is broadly expressed and functions as a critical antioxidant enzyme across tissues. Genetic deficiency in catalase activity demonstrates its essential role in protecting against hydrogen peroxide-mediated cellular toxicity (UniProt: P04040).

In Alzheimer's disease, catalase is upregulated in post-mortem human brain tissue compared to age-matched controls (Chaparral AD proteomics), with a mean log2 fold-change of +0.78 across examined subcellular fractions. This upregulation suggests a potential compensatory oxidative stress response in the AD brain, consistent with the prominent role of hydrogen peroxide and reactive oxygen species in neurodegeneration.