What is "phosphoribosylaminoimidazole carboxylase"

n. (context biochemistry English) An enzyme involved in purine synthesis.

Phosphoribosylaminoimidazole carboxylase (or AIR carboxylase) is an enzyme involved in nucleotide biosynthesis and in particular in purine biosynthesis. It catalyzes the conversion of 5'-phosphoribosyl-5-aminoimidazole ("AIR") into 5'-phosphoribosyl-4-carboxy-5-aminoimidazole ("CAIR") as described in the reaction:

5-aminoimidazole ribonucleotide + CO$\rightleftharpoons$ 5'-phosphoribosyl-4-carboxy-5-aminoimidazole + 2 H