coenzyme is a substance that works with
an enzyme .
 Coenzyme initiate the function of the
enzyme.

 Coenzymes
cannot function on their own
and require the presence of an enzyme.
The non-protein , organic, low molecular
weight and dialysable substance associated
with enzyme function is known as coenzyme.
 Coenzymes from B –complex vitamins: Most of
the coenzymes are the derivatives of water
soluble B-complex vitamins.
 The biochemical functions of B-complex
vitamins are exerted through their respective
coenzymes.

Coenzymes
• Coenzymes act as group-transfer reagents
• Hydrogen, electrons, or groups of atoms can be
transferred
Coenzyme classification
(1) Metabolite coenzymes - synthesized from
common metabolites
(2) Vitamin-derived coenzymes - derivatives of
vitamins
 These
coenzymes are derived from the water
soluble B- Complex vitamins.
B
Complex vitamins :
Thiamin (B-1)
Riboflavin (B-2)
Niacin (B-3)
Pyridoxine (B-6)
Folic acid(B-9)
Cyanocobalamine(B-12)
Biotin(B-7)
Pantothenic Acid(B-5)
of thiamine В1 :
(Thiamine Pyrophosphate).
 Coenzyme

TPP
 Transfers
the Aldehyde or keto groups.
 Functions
: Citric acid cycle, HMP Shunt
pathway, Oxidative decorboxylation.
 Transfers the nerve impulses.
 Coenzymes
of Riboflavin: FMN, FAD.
(Flavin mono nucleotide, Flavin adenine
dinucleotide).
 Hydrogen and Electrons.
Functions : Corbohydrate, Lipid ,
Protein , Purine metabolisms.

 Coenzymes
of Niacin: NAD+, NADP+.
Hydrogen and Electrons.
 Functions : 40 Enzymes.
Carbohydrate, Lipid ,
Protein metabolisms.

Coenzymes of Pyridoxine: PLP (Pyridoxal
phosphate).
 Amino or Keto

Functions : Transamination, decorboxylation,
deamination, Transsulfuration.
 Coenzymes
of Pantothenic acid: Coenzyme A
(CoA)
 Acyl
groups.
Functions : More than 70 enzymes
dependent on CoA in Corbohydrate, Lipid ,
Protein metabolisms .

 Coenzymes
of Biotin: Biocytin.
 CO2

Functions : Gluconeogenesis,
Citric acid cycle, Fatty acid synthesis, Urea
cycle.
 Coenzymes
of Folic acid:
Tetrahydrofolate(TH4 or THF)
 One carbon (formyl, methenyl).
 Functions : One
carbon metabolism.
THF serves as an acceptor or donar of one
carbon units in amino acid and nucleotide
metabolisms.
Purines and pyrimidines.
 Coenzymes
of Cyanocobalamin:
Methylcobalamin, Deoxyadenosyl
cobalamin.
 Methyl groups.
 Aminoacid metabolism.