Inorganic pyrophosphatase 2 (PPA2)

Inorganic pyrophosphatase 2 (PPA2) is a mitochondrial enzyme that catalyzes the highly exergonic hydrolysis of inorganic pyrophosphate (PPi) into two inorganic phosphate (Pi) ions. This reaction is central to driving many cellular biosynthetic processes to completion—including DNA, RNA, and protein synthesis—as it renders complex reactions energetically favorable. PPA2 is encoded by the PPA2 gene on human chromosome 4 and is required for the maintenance of mitochondrial membrane potential and general mitochondrial function. Dysfunction or deleterious mutations in PPA2 are strongly linked to mitochondrial disorders and severe cardiac pathologies, such as sudden cardiac death in infants and children. PPA2 does not have known approved drug modulators, but metabolic inhibitors (e.g., fluoride in yeast) and pathogenic loss-of-function mutations demonstrate the essential biological role of the enzyme. Humans possess two closely related isoenzymes, PPA1 (cytoplasmic) and PPA2 (mitochondrial), which do not fully compensate for one another. The enzyme requires divalent metal ions (Mg²⁺) for activity and has a dimeric structure in eukaryotes. Familial and sporadic cases of early death associated with PPA2 mutation highlight its clinical significance as a disease gene.

Other names

PPA2pyrophosphatase (inorganic) 2mitochondrial inorganic pyrophosphatase

Inhibitors block enzymatic hydrolysis of pyrophosphate, leading to energetic and biosynthetic disruption