Pantothenic acid, also known as vitamin B5, is essential to numerous metabolic processes in the body. It is involved in the synthesis of coenzyme A, which acts as a carrier of acyl and acetyl groups in many vital reactions like the citric acid cycle. Coenzyme A is required for the breakdown of carbohydrates, fats, and proteins to release energy. Pantothenic acid deficiency is rare in humans but can cause burning feet syndrome with symptoms like numbness and pain. Good dietary sources include eggs, meat, yeast, and vegetables.

1. PANTHOTHENIC ACID (B5]
Gandham. Rajeev
Department of Biochemistry,
Akash Institute of Medical Sciences
& Research Centre,
Devanahalli, Bangalore,
Karnataka, India.
E-Mail: gandhamrajeev33@gmail.com

3.  Pantos means ‘everywhere’
 It is widely distributed in nature
 Its metabolic role as a coenzyme A (Discovered by
Lipmann)
 Chemistry:
 Pantothenic acid is composed of pantoic acid
joined to β – alanine by a peptide bond
 It is stable to heat & destroyed by acid & alkali

4.  Absorption: It is present in food either free form
or coenzyme form
 Coenzyme form is hydrolyzed to free form by
intestinal pyrophosphatase
 Free pantothenic acid is absorbed from upper part
of small intestine by sodium dependent transport
system
 Transport it enters portal circulation & transported
to various tissues

5.  Coenzyme A & Form
 Coenzyme A & 4-phosphopantetheine
 Pantothenic acid is first phosphorylated to form 4-
phospho pantothenic acid
 4-phosphopantothenic acid is converted into 4-
phosphopantothenylcysteine by the transfer of
cysteine molecule to 4-phosphopantothenic acid

6.  4-phosphopantothenylcysteine is decarboxylated
to form 4-phosphopantetheine
 4-phosphopantetheine is converted to dephospho
coenzyme A by transfer of AMP
 Dephospho coenzyme A phosphorylated to form
CoA

7. OH - CH2 – C – CH – C – NH - CH2 - CH2 – COO -
CH3
I
O
II
I
CH3
OH
I
Pantoic acid β - Alanine
Pantothenic acid
4-phospho pantothenate
4-phosphopantothenyl cysteine
Cysteine
ATP
ADP
ATP
ADP
4-phosphopantotheine
Dephospho-coenzyme A
Coenzyme A
ATP
PPi

8. CH2 – C – CH – C – NH - CH2 - CH2 – CO-N-CH2 - CH2 - SH
CH3
I
O
II
I
CH3
OH
I
I
O
I
P
I
O
I
P
O
-O - =O
-O - = O – CH2
H
N
NN
N
NH2
I
OH
HH H
-O - =O
O
I
P
I
O-
Ribose - 3 P
Adenine
H
I
Coenzyme A

9.  Role of 4-phosphopantetheine
 4-phosphopantetheine is required for De novo
synthesis of FA
 4-phosphopantetheine is a carrier of acyl groups
 4-phosphopantetheine is attached to ACP of FAS
complex
 4-phosphopantetheine contributes to peripheral
SH group of FAS complex

10.  The functions of pantothenic acid are exerted
through coenzyme A or CoA (A for acetylation)
 Co A is involved in all the metabolisms
 It plays a role in integrating various metabolic
pathways
 Coenzyme A has a terminal thiol or sulfhydryl
group (-SH)
 SH group is the reactive site
 Hence CoA-SH is used

11.  Acyl groups are linked to coenzyme A by thioester
bond, to give acyl CoA
 CoA serves as a carrier of activated acetyl or acyl
groups
 Enzymes requiring Coenzyme A as
cofactor:
 Pyruvate dehydrogenase complex
 α- Ketoglutarate dehydrogenase complex
 FAS complex
 Thiolase, HMG CoA synthase

12.  Acetyl Co A is formed from oxidation of pyruvate
to, amino acids, FA, ketone bodies
 Utilization: Acetyl CoA is utilized for oxidation
through TCA cycle to provide energy
 It essential for formation of Acetylcholine
 Acetylcholine is neurotransmitter
 Acetyl CoA is the substrate for synthesis of FA,
cholesterol, Amino acids, & ketone bodies

13.  Succinyl Co A is formed from propionyl CoA and
α- ketoglutarate
 Propionyl CoA is formed from oxidation of odd
chain FA,valine, isoleucine, methionine
 Utilization succinyl CoA is oxidized through TCA
cycle
 Succinate is utilized for metabolism ketone
bodies
 It is also used for synthesis of heme

14.  Propionyl CoA is formed from oxidation of odd
chain fatty acids, isoleucine, methionine & valine
 Utilization:- Propionyl CoA is converted to
succinyl CoA

15.  Rich soueces: Yeast, eggs, liver & meat
 Good sources:- vegetables & grains
RDA:
Adults - 10 mg/day
Children - 7 mg/day

16.  Deficiency of pantothenic acid (CoA) is rare in
humans
 Experimental studies:
 By giving antagonist of B5 such as ω - methyl
pantathenic acid
 Burning feet syndrome is observed
 It is characterized by numbness & tingling of toes,
burning pain in the feet, sleep disturbances,
dermatitis & depression

17.  Harper’s Biochemistry 25th Edition.
 Fundamentals of Clinical Chemistry by Tietz.
 Text Book of Medical Biochemistry-A R Aroor.
 Text Book of Biochemistry-DM Vasudevan
 Text Book of Biochemistry-MN Chatterjea
 Text Book of Biochemistry-Dr.U.Satyanarana