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Adenylosuccinate lyase (or adenylosuccinase) is an enzyme that in humans is encoded by the ADSL gene.〔(【引用サイトリンク】 url = http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=retrieve&list_uids=158 )〕 Adenylosuccinate lyase converts adenylosuccinate to AMP and fumarate as part of the purine nucleotide cycle. ASL catalyzes two reactions in the purine biosynthetic pathway that makes AMP; ASL cleaves adenylosuccinate into AMP and fumarate, and cleaves SAICAR into AICAR and fumarate. Adenylosuccinate lyase is part of the β-elimination superfamily of enzymes and it proceeds through an E1cb reaction mechanism. The enzyme is a homotetramer with three domains in each monomer and four active sites per homotetramer. Point mutations in adenylosuccinate that cause lowered enzymatic activity cause clinical symptoms that mark the condition adenylosuccinate lyase deficiency. This protein may use the morpheein model of allosteric regulation. == Function == Adenylosuccinate lyase (ASL) is an enzyme that catalyzes two reactions in the ''de novo'' purine biosynthetic pathway. In both reactions it uses an E1cb elimination reaction mechanism to cleave fumarate off of the substrate. In the first reaction, ASL converts 5-aminoimidazole- (N-succinylocarboxamide) ribotide (SAICAR) to 5-aminoimidazole-4-carboxamide ribotide (AICAR) and fumarate. AICAR proceeds through three more reactions before it becomes adenylosuccinate (also called succinyladenosine monophosphate or SAMP), which ASL then splits into adenosine monophosphate (AMP) and fumarate. ASL is important to cells not only because of its involvement in creating purines needed for cellular replication, but also because it helps regulate metabolic processes by controlling the levels of AMP and fumarate in the cell. 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「Adenylosuccinate lyase」の詳細全文を読む スポンサード リンク
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