A COBALT(II) COMPLEX OF VITAMIN B1

Publisher Website
Google Scholar
Abstract
Thiamine (Vitamin B) when phosphorylated gives thiamine pyrophosphate (coenzyme cocarboxylase) (Fig 1) which catalyzes the decarboxylation of a-keto acids. This catalysis is enhanced by the presence of divalent metal such as Mg2+, Mn2+, Cd+, Ni2+, etc. The relative positions of these metal ions in the catalytic efficiency trend depend on the source of the enzyme. For example, for pyruvate decarboxylase from yeasf3 the catalytic efficiency is Mg2+ > Mn2+ > Cd+ > Zn2+ > Fe2+ > Cd2+ while for pyruvate decarboxylase from wheat gem4 the order is Mg 2+ > Cd+ > Zn2+ > Fe 2+ > Ni 2+ > Cd 2+ and from transketolase yeastS the order is Mn2+ > Mg 2+ > Fe 2+ > Ni 2+ > Cd+. Quite naturally, one would like to know what role each metal ion plays in enzymatic processes.