This is a family of 2-dehydropantoate 2-reductases also known as ketopantoate reductases, EC:1.1.1.169. The reaction catalysed by this enzyme is: (R)-pantoate + NADP(+) <=> 2-dehydropantoate + NADPH. AbpA catalyses the NADPH reduction of ketopantoic acid to pantoic acid in the alternative pyrimidine biosynthetic (APB) pathway [2]. ApbA and PanE are allelic [2]. ApbA, the ketopantoate reductase enzyme is required for the synthesis of thiamine via the APB biosynthetic pathway [1].

1: ApbA, the ketopantoate reductase enzyme of Salmonella typhimurium is required for the synthesis of thiamine via the alternative pyrimidine biosynthetic pathway. Frodyma ME, Downs D; J Biol Chem 1998;273:5572-5576. PMID:9488683

2: The panE gene, encoding ketopantoate reductase, maps at 10 minutes and is allelic to apbA in Salmonella typhimurium. Frodyma ME, Downs D; J Bacteriol 1998;180:4757-4759. PMID:9721324