Synthesis of Melatonin
Step 1: Conversion to N-acetylserotonin:
Enzyme: Arylalkylamine N-acetyltransferase (AANAT).
Process: Serotonin is acetylated to form N-acetylserotonin.
Mechanism: AANAT transfers an acetyl group from acetyl-CoA to serotonin, producing N-acetylserotonin.
Step 2: Conversion to Melatonin:
Enzyme: Hydroxyindole-O-methyltransferase (HIOMT).
Process: N-acetylserotonin is methylated to form melatonin.
Mechanism: HIOMT transfers a methyl group from S-adenosylmethionine (SAMe) to N-acetylserotonin, producing melatonin.
Significance
Sleep-Wake Cycle: Melatonin regulates the sleep-wake cycle by signaling to the body when it's time to sleep, aligning the internal clock with external light-dark cycles.
Antioxidant Properties: Melatonin has antioxidant effects, protecting cells from oxidative stress.
Immune Function: It supports the immune system and has anti-inflammatory properties.
Clinical Relevance
Sleep Disorders: Melatonin supplements are used to treat conditions like insomnia, jet lag, and circadian rhythm disorders.
