INTRODUCTION OF VITAMIN
- Organic molecules, essential for the normal growth and development, required in tiny amounts
- Cannot be synthesized by mammalian cells, must be supplied in the diet
THE CLASSIFICATION OF VITAMINS
Folic Acid VB11 ? VB9
Vitamin C VC
- Fat-soluble：VA, VD, VE and VK
WATER SOLUBLE VITAMINS: CHARACTERISTICS
- Organic Structure
- Non-energy Producing
THE B VITAMINS
Chief Functions – Important as Coenzymes
iv) Pantothenic Acid &
Involved in Energy Metabolism
– Vitamin B-6 involved in Protein
– Folate & Vitamin B-12 involved
in Cell Replication
– Therapeutic doses of Niacin
WATER SOLUBLE VITAMINS VS.
FAT SOLUBLE VITAMINS
Vitamins are derived from a variety of foods.
PYRIDOXINE (VITAMIN B6)
- Vitamin B6 is used to collectively represent
the three compounds namely:
ii. Pyridoxal and
- Active form of Pyridoxine:
Pyridoxal phosphate (PLP)
Rich sources are dried yeast, rice polishing, wheat germs, cereals, legumes, oil seeds, egg, milk, meat, fish and green leafy vegetables.
- Requirement of vitamin B6 is related to dietary protein intake, as it is involved as coenzyme in many metabolic reactions of amino acid metabolism
- Adults : 2 mg/day
- Infants : 0.3 – 0.4 mg/day
- Vitamin B6 compounds are pyridine derivatives
- They differ from each other in the structure of a functional group attached to 4th carbon in the pyridine ring
i. Pyridoxine: Primary Alcohol
ii. Pyridoxal: Aldehyde form while
iii. Pyridoxamine: Amine
CO – ENZYME FORM
- Sulphur containing amino acid
- Heme Synthesis
- Production of Niacin
- Neurological manifestation
- Dermatological manifestation
- Hematological manifestation
- Vitamin H
- Vitamin 7
- Co-enzyme R
- Anti egg white injury factor
Biotin is a sulphur containing B-complex vitamin.
- In old literature Biotin was known as anti egg white injury factor.
- Biotin was isolated in 1942 by Vincent du Vigneaud, who was awarded Nobel prize in 1955.
- Normal bacterial flora of the gut will provide adequate quantity of Biotin
- Moreover, it is distributed ubiquitously in plant and animal tissues
- Liver, yeast, peanut, soybean, milk and
egg yolk are rich sources.
About 200 – 300 mg will meet the daily requirements.
- Biotin is a hetrocyclic monocarboxylic acid
- Sulphur containing water soluble B vitamin
- Structure of the compound was worked out by du Vigneaud
- It consist of two fused rings,
i. Imidazole and
ii. Thiophene derivative
CO-ENZYME ACTIVITY OF BIOTIN
- Biotin present in liver as Biocytin (active form of Biotin)
- Biotin act as a co-enzyme for:
- In the First Step:
A molecule of CO2 is captured by Biotin
- The resulting carboxybiotin contains carboxyl group covalently attached to the nitrogen of Biotin molecule.
- The energy required for this reaction is provided by ATP
- In the second step:
Activated carboxyl group is transferred to the substrate and A free biotynyl enzyme is regenerated.
Biotin Requiring CO2 Fixation Reactions
- Acetyl CoA carboxylase:
- This enzyme adds CO2 to acetyl coA to form malonyl CoA.
- This is the rate limiting reaction in biosynthesis of fatty acids
2. Propionyl CoA Carboxylase:
- It is another Biotin requiring Enzyme
3. Pyruvate Carboxylase:
- Fixes CO2 to Pyruvate to form Oxaloacetate
- Required for conversion of β methyl crotonyl CoA to β methyl gluconyl CoA
- Avidin, a protein present in egg white has great affinity to biotin
- Hence intake of raw (unboiled) egg may cause biotin deficiency
- Biotin deficiency was experimentally produced by giving raw egg white
- Therefore biotin was originally named as anti-egg-white-injury-factor
Biotin deficiency may be produced by:
- Large quantity of avidin
- Prolonged use of antibacterial drugs
- Very rarely, holocarboxylase synthetase enzyme is deficient or absent
- Leiner’s disease occurs in breast fed young infants with persistent diarrhea
- Atrophic Glossitis
- Muscle pain
Other Biochemistry Notes :-
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