Thiamin pyrophosphate (TPP) is an essential cofactor
required by enzymes involved in a number of
important metabolic processes, including the production
of acetyl-CoA, the tricarboxylic acid cycle, the
pentose phosphate pathway/Calvin cycle, branched
chain amino acid biosynthesis, and isoprenoid biosynthesis
(Hohmann and Meacock, 1998). Due to its
central role in intermediary metabolism, TPP is required
by all biological systems. While TPP is synthesized
de novo in plants and microbes, animals and
humans must derive this cofactor through the intake
of free (unphosphorylated) thiamin (vitamin B1). Due
to the abundance of thiamin in whole grains and green