TABLE 5.

NADase activity of Sir2 proteins

Sir2 protein	23°	37°
sir2-604	55 ± 29	29 ± 13
sir2-614	60 ± 22	6 ± 3
sir2-620	60 ± 39	23 ± 6
sir2-H364Y	3 ± 2	1.6 ± 1.5

The ability of the indicated Sir2 proteins to hydrolyze NAD in the presence of a substrate bearing an acetylated lysine was measured. Values are expressed as a percentage of a wild-type control purified and tested at the same time. The sir2-H364Y protein has been previously shown to have minimal activity in in vitro deacetylase assays (Tanny et al. 1999; Imai et al. 2000). In these assays, wild-type Sir2 had ∼5% higher activity at 37° vs. 23°.