Serum paraoxonase-1 (PON1) activity

Method

Serum paraoxonase-1 enzymatic activity measured by hydrolysis of a defined substrate - paraoxonase activity with paraoxon, or arylesterase activity with phenyl acetate - expressed as units per mL. The substrate is recorded on the edge; the two activities reflect different properties of the enzyme and are affected differently by the PON1 Q192R polymorphism.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

A specific enzyme activity, not a bulk assay. Its near-miss is CAT:outcome/total-antioxidant-capacity (PMID 39196774): both are described as antioxidant status and both rise with benefit, but this is one HDL-associated enzyme measured by a defined substrate reaction while total antioxidant capacity is an aggregate redox assay dominated by urate and albumin - that can rise with no change here at all. Confusable also with serum butyrylcholinesterase, another serum esterase assayed by substrate hydrolysis in the same panel and reported in the same units, but a different enzyme with a different clinical meaning.