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In enzymology, a S-ribosylhomocysteine lyase () is an enzyme that catalyzes the chemical reaction :S-(5-deoxy-D-ribos-5-yl)-L-homocysteine L-homocysteine + (4S)-4,5-dihydroxypentan-2,3-dione Hence, this enzyme has one substrate, S-(5-deoxy-D-ribos-5-yl)-L-homocysteine, and two products, L-homocysteine and (4S)-4,5-dihydroxypentan-2,3-dione. This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is S-(5-deoxy-D-ribos-5-yl)-L-homocysteine L-homocysteine-lyase (). Other names in common use include S-ribosylhomocysteinase, and LuxS. This enzyme participates in methionine metabolism. Furthermore, LuxS is involved in the synthesis of autoinducer AI-2 (autoinducer-2), which is plays a role in quorum sensing in a certain number of bacterial species. LuxS converts S-ribosylhomocysteine to homocysteine and 4,5-dihydroxy-2,3-pentanedione (DPD); DPD can then spontaneously cyclisize to active AI-2. AI-2 is a signalling molecule that is believe to act in interspecies communication by regulating niche-specific genes with diverse functions in various bacteria, often in response to population density. However, an unequivocally AI-2 related behavior was found to be restricted primarily to bacteria bearing known AI-2 receptor genes. Thus, while it is certainly true that some bacteria can respond to AI-2, it is doubtful that it is always being produced for purposes of signalling. LuxS is a homodimeric iron-dependent metalloenzyme containing two identical tetrahedral metal-binding sites similar to those found in peptidases and amidases. ==Structural studies== As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「S-ribosylhomocysteine lyase」の詳細全文を読む スポンサード リンク
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