Cofactors are non-protein molecules that are required for enzyme activity and assist in biochemical transformations. They can be inorganic, such as metal ions like zinc, iron, and copper, or organic like vitamins. Organic cofactors, also called coenzymes, are low molecular weight organic compounds that participate in enzymatic reactions and include prosthetic groups that are tightly bound to proteins or cosubstrates that bind transiently. Common examples of coenzymes include nicotinamide adenine dinucleotide (NAD+) and vitamins. Cofactors activate apoenzymes and are essential for biological activity of enzymes.

1. Cofactor Binding
 Cofactor bind with the inactive enzyme/Apo enzyme
to activate the enzyme OR the binding of cofactor
with Apo enzyme convert it to Holo enzyme
 Some cofactors are inorganic, such as the metal atoms
zinc, iron, and copper in various oxidation states.
 Others, such as most vitamins, are
organic. Cofactors are generally either bound tightly to
active sites, or may bind loosely with the enzyme

2. Cofactor
 Cofactor
 Non protein chemical copound
 Required for enzyme activity as catalyst
 Considered as helper molecules
 Assist the biochemical transformation
 Cofactors may be organic or inorganic

3. .
 ChEBI Name: “ cofactor”
 ChEBI ID : CHEBI:23357
 Gene ontology ( 0048037)
 Gene ontology Annotation ( 905 annotation)

4. Classification
 Classification of cofactor
These are classified
into two types of cofactors
 Inorganic cofactors
 Organic cofactors

5. 1.Inorganic cofactors
These are also devided into two group
 Metal ions
 Iron –sulfur clusters
Metal ions
 Metal ions are common cofactors
 Some enzymes, referred to as metalloenzymes, cannot
function without a bound metal ion in the active site

6. ..
 In nutrition, the list of essential trace elements reflects
their role as cofactors.
 In humans these are
includes iron, magnesium, manganese, cobalt, copper,
zinc, and molybdenum.
 Although chromium deficiency causes impaired
glucose tolerance, no human enzyme that uses this
metal as a cofactor has been identified
 Iodine is also an essential trace element, but this
element is used as part of the structure of thyroid
hormones rather than as an enzyme cofactor

7. Example
 Mg2+ is used in glycolysis.
 In the first step of converting glucose to glucose 6-
phosphate
 before ATP is used to give ADP and one phosphate
group,
 ATP is bound to Mg2+ which stabilizes the other two
phosphate groups so it is easier to release only one
phosphate group.

8. .
ChEBI Name: magnesium(2+)
ChEBI ID : CHEBI:18420
Secondary ChEBI IDs CHEBI:49736
CHEBI:6635
CHEBI:13379
CHEBI:25112
Gene ontology GO:0015444

9. Iron –sulfur clusters
 Iron-sulfur clusters are complexes of iron and sulfur atoms
held within proteins by cysteinyl residues.
 They play both structural and functional roles, including
electron transfer, redox sensing, and as structural modules.
 These clusters have many unique properties that are not
found in amino acids or other organic compounds.
 [Fe-S] clusters participate in electron transfer, substrate
binding/activation, iron/sulfur storage, regulation of gene
expression, and enzyme activity
 Definition
An iron-sulfur cluster is a unit comprising two or
more iron atoms and bridging sulfur ligands.

10. .
ChEBI Name: iron-sulfur cluster
ChEBI ID : CHEBI:30408
Secondary ChEBI IDs: CHEBI:5976, CHEBI:24878
Gene Ontology : GO:0051536

11. 2.Organic cofactors
 Organic cofactors also called as coenzyme
 Coenzyme are non-protein ,low molecular weight
organic compound that participating in enzymatic
reaction
 Can not function alone
 Can be used several time when paired with enzyme

12. ,
They have two groups or sides
 prosthetic group
 cosubstrate
 Prosthetic group is tightly covalently and permanently
bound to protein
 Cosubstrate is transiently bound to protein may be
released from protein at some time and then rebind
 Vitamin and essential nutrients are common example
of coenzyme

13. Function of coenzyme
 The coenzyme is essential for the biological activity of
the enzyme.
• A coenzyme is a low molecular weight organic
substance, without which the enzyme cannot exhibit
any reaction.
• One molecule of the coenzyme is able to convert a large
number of substrate molecules with the help of
enzyme.

14. Nicotinamide Adenine Dincleotide
(NAD+ )
• This is a coenzyme synthesized from Nicotinamide, a
member of vitamin B complex.
• The structure of NAD+ could be written as:
Nicotinamide-Ribose-P-P-Ribose-Adenine
• The reversible reaction of lactate to pyruvate is
catalyzed by the enzyme lactate dehydrogenase, but
the actual transfer of hydrogen is taking place on the
coenzyme, NAD+ .

15. mechanism

16. .