Vitamin B6 and its family members: Pyridoxine, Pyridoxal & Pyridoxamine.
Free online lectures of Biochemistry especially for medical students by Biochemistry Club
Pyridoxine (Vitamin B6)
- Vitamin B6 contains 3 important members. These only differ from each other by the functional groups attached to each.
- These are all derivatives of Pyridine:
- Pyridoxine (alcohol)
- Pyridoxal (aldehyde) and
- The main form of Vitamin B6 in food is Pyridoxine which is later converted into Pyridoxal and Pyridoxamine in the body.
- Active form of Pyridoxine is Pyridoxal phosphate (PLP).
- It is synthesized by Pyridoxal kinase, utilizing ATP.
Functions of Pyridoxal Phosphate
- The Pyridoxal phosphate (PLP) acts as a coenzyme for many reaction is in amino acid metabolism.
- These are:
- Metabolism of Sulfur containing AA
- Heme synthesis
- Production of niacin
- The Transamination reactions are catalyzed by the Aminotransferases (Transaminases).
- These reactions need PLP as a coenzyme.
- Example is: Alanine + Alpha ketoglutarate → Pyruvate + Glutamic acid (Enzyme Alanine transaminase)
- The decarboxylation reactions require PLP as a coenzyme.
- Examples are:
- Glutamate → GABA (inhibitory neurotransmitter) – Vitamin B6 deficiency may cause convulsions in children.
- Histidine → Histamine
- 5-hydroxy tryptophan → Serotonin
- Cysteine → Taurine
- Serine → Ethanolamine.
3. Metabolism of Sulfur containing amino acids
- Methionine and Cysteine (sulfur containing amino acids) also require PLP as a …
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