<p>This family represents thiamine-monophosphate kinase, an enzyme that converts thiamine monophosphate into thiamine pyrophosphate (TPP, coenzyme B1), an enzyme cofactor. Thiamine monophosphate may be derived from de novo synthesis or from unphosphorylated thiamine, known as vitamin B1. Eukaryotes lack this enzyme, and add pyrophosphate from ATP to unphosphorylated thiamine in a single step. </p>