4g1c
Human SIRT5 bound to Succ-IDH2 and Carba-NAD
Structural highlights
FunctionSIR5_HUMAN NAD-dependent lysine demalonylase and desuccinylase that specifically removes malonyl and succinyl groups on target proteins. Activates CPS1 and contributes to the regulation of blood ammonia levels during prolonged fasting: acts by mediating desuccinylation of CPS1, thereby increasing CPS1 activity in response to elevated NAD levels during fasting. Activates SOD1 by mediating its desuccinylation, leading to reduced reactive oxygen species. Has weak NAD-dependent protein deacetylase activity; however this activity may not be physiologically relevant in vivo. Can deacetylate cytochrome c (CYCS) and a number of other proteins in vitro.[1] [2] [3] [4] Publication Abstract from PubMedCarba-NAD is a synthetic compound identical to NAD except for one substitution, where an oxygen atom adjacent to the anomeric linkage bearing nicotinamide is replaced with a methylene group. Because it is inert in nicotinamide displacement reactions, carba-NAD is an unreactive substrate analogue for NAD consuming enzymes. SIRT3 and SIRT5 are NAD consuming enzymes that are potential therapeutic targets for the treatment of metabolic diseases and cancers. We report an improved carba-NAD synthesis, including a pyrophosphate coupling method that proceeds in approximately 60% yield. We also disclose the x-ray crystal structures of the ternary complexes of SIRT3 and SIRT5 bound to a peptide substrate and carba-NAD. These x-ray crystal structures provide critical snapshots of the mechanism by which human sirtuins function as protein deacylation catalysts. Synthesis of Carba-NAD and the Structures of Its Ternary Complexes with SIRT3 and SIRT5.,Szczepankiewicz BG, Dai H, Koppetsch KJ, Qian D, Jiang F, Mao C, Perni RB J Org Chem. 2012 Jul 31. PMID:22849721[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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