Role of sirtuins in cell metabolism pathway- Their significance in longevity
Sirtuins or Sirt proteins
Sirtuins are interesting class of proteins and are widely distributed in organisms ranging from microscopic bacteria, eukaryotes, yeast etc. to mammals including humans.
They are named after an yeast " silent mating-type information regulation two" i.e. they are Silent Information Regulators.
In humans these proteins are believed to exist in 7 forms as SIRT1, 2, 3, 4, 5, 6, and SIRT7.
Metabolic activity: Sirtuins are considered to be influencing metabolism through their
1. deacetylase activity or
2. mono-ribosyltransferase activity
By deacetylase activity they deacetylate by hydrolysis at acetyl- lysine residues in presence of NAD ( Nicotinamide adenine di-nucleotide. This is energy dependent reaction.
Some of them mediate acetyl CoA synthetase activity to produce acetyl-CoA which is primary substrate in citric acid pathway of cell energy production.
Their significance in health.
They are claims that sirtuins are involved in
1. Enhancement of longevity or anti aging.
2. Enhancement of memory.
3. In therapy of diabetes type-II.
4. Anti-cancer activity.
5. Anti-inflammatory activity.
6. Hair growth enhancer
Longevity or aging. They are thought to regulate life span by repair of damaged and stressed DNA and gene expression that are altered by age.
They are thought to enhance mitochondria energy out-put in times of caloric restriction or depleted energy production so as to slow the aging process. This process even prevents cardiac dysfunction due to muscle aging.
Memory. Recent studies reported them to possess memory enhancing activity. Lack of their production decreased memory. But confirmation about their memory enhancement activity after use of diet supplements which activate them is still awaited.
In Diabetes they are thought to minimise Type-II diabetes because of their hepatic regulation of gluconeogenesis and also enhancement of insulin sensitivity.
Over all activity appears due to their restriction of calorie consumption by 30%.
Resveratrol influence on sirtuins
Resveratrol, a active constituent found in red wine, it is believed to stimulate SIRT1 protein activity increases cell survival. It is found to trigger calorie restriction by stimulating Sir2 thereby increasing DNA stability. This is thought to enhances cell types lifespan by 70%. This resveratrol common source is the skin of grapes so grape wine is its supplement. It is found to have anti-cancer, anti-inflammatory and also anti-diabetic activity. These all of the actions are supposed to be mediated through sirtuins.
Resveratrol also has anti-oxidant properties even but its mode of activity is thought to be primarily through sirt proteins.
So over all this focuses on low calorie nutrition for longer and healthy life.
So the phrase "limited diet promote longevity" is right. :-)