Sirtuin

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Sirtuin is a class of enzyme, specifically NAD-dependent histone deacetylases (class 3), found in both prokaryotes (organisms without a membrane for their cell's nucleus) and eukaryotes (organisms whose cells' nucleus have a membrane). They have been known to affect cellular metabolism through selective gene expression in eukaryotes (plants and animals). The name comes from silent mating type information regulation two, the gene responsible for cellular regulation in yeast.

Contents 1 Sirtuins in organisms 1.1 Sirtuins in lower eukaryotes 1.2 Sirtuins in higher eukaryotes 2 Sirtuins types 3 Companies associated with the sirtuin enzymes 3.1 Elixir Pharmaceuticals 3.2 Sirtris 4 See also 5 External links

[edit] Sirtuins in organisms

[edit] Sirtuins in lower eukaryotes

In yeast, roundworms, and fruitflies[1], sir2 is the name of the sirtuin-type enzyme. This research was begun in 1991 by Leonard Guarente of Harvard Medical School [2]http://web.mit.edu/newsoffice/2000/guarente.html.

[edit] Sirtuins in higher eukaryotes

[edit] Sirtuins types

Sirtuins are classed according to their sequence of amino acids. Prokaryotics are in class U. In yeast (a lower eukaryote), sirtuin was initially found and named sir2. In more complex mammals there are seven known enzymes which act as on cellular regulation as sir2 does in yeast. These genes are designated as belonging to different classes, depending on their amino acid sequence structure.[3] [4].

Class	Human name	Yeast name	Mouse name
Ia	SIRT1[5]	Sir2 or Sir2p, Hst1 or Hst1p	Sir2-beta
Ib	SIRT2, SIRT3	Hst2 or Hst2p	Sir2l2, Sir2l3
Ic		Hst3 or Hst3p, Hst4 or Hst4p
II	SIRT4		SIRT4
III	SIRT5		SIRT5
IVa	SIRT6[6]		SIRT6
IVb	SIRT7		SIRT7
U<	Found only in Gram-positive bacteria

Sirtuin list based on this diagram from [7].

[edit] Companies associated with the sirtuin enzymes

[edit] Elixir Pharmaceuticals

Founded by Leonard Guarente of Harvard Medical School, with Cynthia Kenyon of the University of California at San Francisco, with the intentions of treating aging through drugs which affect metabolism [8].

[edit] Sirtris

Sirtris was co-founded by David Sinclair of the Harvard Medical School, and Dr. Christoph Westphal is the CEO. Sirtris is associated with the World Transhumanist Association [9].

[edit] See also

• Sir2
• Resveratrol
• Biological immortality
• Caloric restriction

[edit] External links

• New York Times article about sirtuin activators.
• Patient Care article by David A. Sinclair, PhD and Evan W. Kligman, MD.
• Elixer Pharmiceuticals
• Sirtris Pharmaceuticals™