Purification and properties of an enzyme duet, phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazolesuccinocarboxamide synthetase, involved in the biosynthesis of purine nucleotides de novo

Purification and some properties of an adjacent pair of enzymes in the biosynthetic pathway to AMP, phosphoribosylaminoimidazole carboxylase (EC 4.1.1.21) and phosphoribosylaminoimidazolesuccinocarboxamide synthetase (EC 6.3.2.6), are described. The enzymes form a duet, which may be regarded as a single molecule with a dual function, or as two very similar substances.