Posted by Tim Tyler on CR Society. I feel better now.

This latest study probes how Sir2 is activated by calorie restriction.
The authors report that a coenzyme related to NAD, called NADH
(nicotinamide adenine dinucleotide) inhibits Sir2 by blocking the
action of NAD. During calorie restriction, levels of NADH decline in
cells. This decrease in NADH allows NAD to better activate Sir2 and
thereby extend life span.

"These findings provide a simple model for activation of Sir2 and
extension of life span by calorie restriction," the authors write.
"Our findings suggest that the NAD/NADH ratio can serve a critical
regulatory function, determining the life span of yeast mother cells.
A reduction in this nucleotide activates Sir2 to extend the life span
in calorie restriction."

http://eurekalert.org/pub_releases/2003-12/cshl-mhu121903.php


Tim

What does straight niacinamide/nicotinamide do to the ratio?

What does straight niacinamide/nicotinamide do to the ratio?

Description of the effect of nicotinamide on the equiv. human sirutin:

``Nicotinamide and PNC1 govern lifespan extension by calorie restriction
in Saccharomyces cerevisiae [...]

We have recently shown that Sir2 and its closest human homologue SIRT1,
a p53 deacetylase, are strongly inhibited by the vitamin B3 precursor
nicotinamide. Here we show that increased expression of PNC1
(pyrazinamidase/nicotinamidase 1), which encodes an enzyme that
deaminates nicotinamide, is both necessary and sufficient for lifespan
extension by calorie restriction and low-intensity stress. [...]''

- http://calorierestriction.org/pmid/?n=12736687