Past decade researches on science of aging, has identified important genes and pathways that control the aging process. Included among these is a family of NAD+–dependent protein deacetylases called sirtuins. Sir2 (silent information regulator 2) protein of yeast Sacchromyces cervisiae and its conserved orthologues in other prokaryotes and eukaryotes are collectively known as sirtuins. Initially SIRT2 was shown to extend lifespan in budding yeast. Since then, many sirtuins have been shown to regulate longevity in other organisms including mammals. Sirtuins exhibit deacetylase or ADP-ribosyltransferase activity and they belong to the class III protein deacetylase family of enzymes which require NAD+ as a co-factor for their enzymatic activity. Requirement of NAD+ for their enzymatic activity connects sirtuins to cell metabolism and age related diseases. High levels of NAD+ stimulate the sirtuins activity and high levels of NAM inhibit SIRT2 activity. 1382183844.php