Biochemistry | Assessment | Repoort

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BIOCHEMISTRY
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BIOCHEMISTRY1
Pyruvate dehydrogenase complex is formed by the combination of three enzymes
which is responsible for the conversion of pyruvate to acetyl-CoA. This happens by a
process known as pyruvate de-carboxylation. The important catalytic coenzymes involved in
this process are lipoic acid, thiamine pyrophosphate and FAD. The Pyruvate changes to
acetyl CoA by three main steps of de-carboxylation, transfer and oxidation of acetyl group
into Co-enzyme A.
The Pyruvate leads to acetyl-CoA formation by a three step reaction. Firstly,
decarboxylation: Thiamine pyro phosphate is combined with the pyruvate and decarboxylated
in order to yield hydroxyethyl Thiamine pyro phosphate (Martínez-Reyes et al., 2016).
Thiamine Pyro Phosphate in pyruvate dehydrogenase component, is called as ‘prosthetic
group’ because the very carbon atoms linked between sulfur and nitrogen atoms within
thizaole ring has been reported to be more acidic carbon groups whose kinetic values ‘pKa’
values are very near to 10. This biological reaction is then catalyzed by pyruvate de-
hydrogenase that is an integral component of multi enzyme complex. Carbon which is at the
center of Thiamine pyro phosphate is afterwards ionized to release a carbanion being added
to pyruvate’s carbonyl group. By decarboxylation, Thiamine pyro phosphate’s positively
charged ring then steadies the molecular negative charge that is then transferred to this ring.
The protonation process finally yields the very hydroxyethyl thiamine pyro phosphate.
Pyruvate + THYAMINE PYROPHOSPHATE (conenzyme thiamine pyrophosphate) +
2 H+ --> Hydroxyehthyl-THYAMINE PYROPHOSPHATE+ CO2
To conceive the acetyl group, the Thiamine pyro phosphate is further oxidized in this
oxidation process of the TCA cycle. At the same time, the hydroxyl ethyl group is moved to
lipoamide which is lipoic corrosive inferred that connects to the side chain of the very lysine
buildup by an amide linkage. This makes the development of a thioester bond which is very