E-Book Biochemistry ( Cofactor Coenzyme )

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ENZYME
BIOCHEMISTRY

Co-Factors and

Co-Enzymes

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What is cofactor

A cofactor is a substance that isn't a protein but
helps with biological chemical reactions.
Cofactors may be metal ions, organic compounds
or other chemicals such as calcium ion and zinc ion.

Cofactors will attach near the
substrate binding site to
facilitate the binding of the
substrate to the enzyme
Cofactors can be classed as
“prosthetic groups” or
“coenzymes” depending on how
tightly they are bound to the
enzyme

Quick learning!!!
Prosthetic groups

These can be organic vitamins, sugars, lipids, or
inorganic metal ions
Unlike coenzymes or cofactors, these groups bind
very tightly or covalently to an enzyme to aid in
catalyzing reactions
These groups are often used in cellular respiration
and photosynthesis.

What is coenzyme

A coenzyme is an organic non-protein compound that binds
with an enzyme to catalyze a reaction
Coenzymes are often broadly called cofactors, but they are
chemically different

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What is the importance of cofactor and
coenzyme for enzymes?

An enzyme without a coenzyme is called an apoenzyme.
When an enzyme gains a coenzyme, it then becomes a holoenzyme
cofactor and coenzyme help an enzyme or protein to function
appropriately
Without coenzymes or cofactors, enzymes cannot catalyze reactions
effectively.
In fact,reactions cannot occur at the normal catalyzed rate, then an
organism will have difficulty sustaining life.

Quick View!!!!

Apoenzyme-Inactive protein
holoenzyme-Whole
enzyme(active)

How Cofactor works

A variety of cofactors are found in the active site of the
enzyme. The cofactor will aid in substrate binding to help
enzyme carry out catalysis.



An apoenzyme is an inactive enzyme that lacks a
cofactor, whereas a holoenzyme is a complete enzyme that
has a cofactor.

For example; during DNA replication, DNA Polymerase
use Magnesium ion as a cofactor by stabilizing the

negative charges of DNA molecules which help enzyme
carry out the catalysis.

Balint, E., & Unk, I. (2020). Selective Metal Ion Utilization Contributes to the Transformation of the Activity of Yeast Polymerase η from DNA Polymerization toward RNA Polymerization. International Journal of Molecular Sciences, 21(21), 8248. https://doi.org/10.3390/ijms21218248
‌

Examples of Cofactors

Cofactor can be organic or inorganic.
Inorganic cofactor is metal ions like iron and zinc that
bind tightly with enzyme.
Organic cofactors is coenzyme like vitamins that bound
loosely with enzyme.

Difference Between Coenzyme and Cofactor | Definition, Properties, Functions, Examples. (2017, May 25). Pediaa.com. https://pediaa.com/difference-between-coenzyme-and-cofactor/

Examples of or‌‌ganic cofactor



19.2: Enzyme Cofactors. (2017, August 5). Chemistry LibreTexts. https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Map%3A_Fundamentals_of_General_Organic_and_Biological_Chemistry_(McMurry_et_al.)/19%3A_Enzymes_and_Vitamins/19.02%3A_Enzyme_Cofactors

Examples of ino‌ rganic cofactor

How Coenzyme Works

Helps the catalysis actions or reactions of its enzymes
Loosely bind to enzymes to aid them fulfill their functions.
Also known as cofactor but differ in chemical structure.
Do not work by itself

Redox Reactions Transferring groups

Role of Coenzyme

Antioxidants

E.g. : Coenzyme Q10( CoQ10 )

Energy Production

Coenzyme A Nicotinamide Adenine
Dinucleotide(NAD)
Also known as Acetyl-CoA
Derives from vitamin B5 Also known as NAD
Derived from vitamin B3
Function
1.Initiate intracellular production of Function
1.Vital in Citric Acid Cycle especially electron
fatty acid
2.Initiate Citric Acid Cyle or Kreb Cycle. transport chain.
2.Natural antioxidant

Vitamins

Example of Coenzymes

Non-vitamins

Adenosine Triphosphate

Common name is ATP
End product of Citric Acid Cycle

Function
1.Supply energy for necessary chemical reactions
2.Supply energy for muscle contraction

The Differences Between
Co-Factors and Co-Enzymes

CHARACTERISTIC CO-FACTORS CO-ENZYMES

DEFINITION A co-factor is the non-protein part of an Co-enzymes are organic non-protein part

enzyme that is essential for the enzyme’s of an enzyme which functions as cofactors


activity as a catalyst. for the function of catalysis.

RELATIONSHIP The co-factor is a broader group that
Co-enzymes are a type of cofactor.
contains coenzymes and prosthetic

groups.

Co-factors are chemical compounds that
Co-enzymes are molecules composed of

can either be compounds, elements, or
multiple elements.
ions.
COMPOUND

NATURES

Co-factors can be organic or inorganic
Co-enzymes are organic molecules.
compounds.

BOND
Co-factors are either loosely bounded or
Co-enzymes assist in the biological

NATURES covalently bonded to an enzyme. transformation of the enzyme for its


function.

FUNCTIONS Co-factors are essential for the function
Co-enzymes assist in the biological

of the enzyme. transformation of the enzyme for its


Co-factors increase the rate of the
function.
reaction between the enzyme and the

Co-enzymes serve as carriers to the

substrate. enzymes.

ROLE Co-factors participate in the removal of
Co-enzymes often remove electrons from

electrons, protons, or chemical groups
the substrate and transfer them to other

from the substrate as a part of catalysis.
molecules.

REMOVAL Inorganic co-factors can only be removed
Co-enzymes can be easily removed from

from the enzymes by denaturation of the
the enzyme via chemical methods.

enzyme.

PRODUCTION Co-factors can either be produced within
Co-enzymes are produced within the body

the body or are consumed as a part of the
by different pathways.

diet.

EXAMPLES Examples of co-factors include metal ions
Examples of co-enzymes include vitamins,

like Zn2+, flavin, etc. biotin, coenzyme A, etc.

CONCLUSION

Cofactor and coenzyme are


both molecules that help an


enzyme or protein to function


appropriately. Coenzymes are organic


molecules and quite often bind


loosely to the active site of an


enzyme and aid in substrate


recruitment, whereas cofactors


do not bind the enzyme.

Even though there are many

differences between both of


them, there is also some

similarities between them for
example both coenzymes and

cofactors are small, non-protein


substances.

Both cofactor and coenzyme play

a vital role in the metabolic


functions of the cell by helping

the enzymes to catalyze the


biochemical reactions. Without

them, the enzymatic reaction will

take such a longer time to carries


out their work.

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REFERENCES

Sapkota, A. (2021, March 31). Cofactors vs Coenzymes- Definition, 11

Key Differences, Examples. The Chemistry Notes.

https://thechemistrynotes.com/cofactors-vs-coenzymes/

19.2: Enzyme Cofactors. (2017, August 5). Chemistry LibreTexts.

https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Map%

3A_Fundamentals_of_General_Organic_and_Biological_Chemistry_(McM

urry_et_al.)/19%3A_Enzymes_and_Vitamins/19.02%3A_Enzyme_Cofactor

s

Editors. “Cofactor.” Biology Dictionary, Biology Dictionary, 22 Feb. 2017,

biologydictionary.net/cofactor/

“What Are Coenzymes?” News-Medical.net, 17 Feb. 2021, www.news-

medical.net/life-sciences/What-are-Coenzymes.aspx.

Khan Academy. (n.d.). The citric acid cycle | cellular respiration (article).

Khan Academy. Retrieved December 15, 2022, from

https://www.khanacademy.org/science/biology/cellular-respiration-and-

fermentation/pyruvate-oxidation-and-the-citric-acid-cycle/a/the-citric-

acid-cycle

Coenzymes - role and types of Coenzymes with examples - TOPPR-

guides. Coenzymes - What is Role of Coenzymes? (n.d.). Retrieved

December 11, 2022, from

https://www.toppr.com/guides/physics/atomic-and-molecular-

structure/coenzymes-what-is-role-of-coenzyme/

B. D. Editors. (2019, October 5). Coenzyme: Definition, function &

examples. Biology Dictionary. Retrieved December 11, 2022, from

https://biologydictionary.net/coenzyme/