Vitamin B1 Converted to the Coenzyme Thiamin Pyrophosphate

Abstract

The first human disease to be identified as arising from nutritional deficiency was beriberi, in Southeast Asia. Thiamin was isolated from rice husks, shown to cure the disease symptoms, and designated as the first vitamin (later classified as vitamin B1). The thiazolium heterocyclic ring in the active coenzyme form, thiamin pyrophosphate (thiamin-PP), is readily dissociated to a carbanion that adds to α-keto acid cosubstrates (e.g. pyruvate, α-ketoglutarate) to provide low-energy paths to decarboxylation. B1 interacts with coenzyme forms of B2, B3, and B5 for oxidative decarboxylations of pyruvate to acetyl-CoA and ketoglutarate to succinyl-CoA in the central metabolism.