|
In enzymology, an ''ent''-copalyl diphosphate synthase () is an enzyme that catalyzes the chemical reaction: Hence, this enzyme has one substrate, geranylgeranyl pyrophosphate, and one product, ''ent''-copalyl pyrophosphate.〔(【引用サイトリンク】 url = http://www.chem.qmul.ac.uk/iubmb/enzyme/EC5/5/1/13.html )〕 This enzyme participates in gibberellin biosynthesis.〔(【引用サイトリンク】 url = http://www.genome.jp/kegg-bin/show_pathway?ec00904 )〕 This enzyme belongs to the family of isomerases, specifically the class of intramolecular lyases. The systematic name of this enzyme class is ''ent''-copalyl-diphosphate lyase (decyclizing). Other names in common use include ''ent''-kaurene synthase A, and ''ent''-kaurene synthetase A.〔 ==Bifunctionality== ''ent''-Copalyl diphosphate synthases from fungi and mosses also have a distinct ''ent''-kaurene synthase activity associated with the same protein molecule. The reaction catalyzed by ''ent''-kaurene synthase is the next step in the biosynthetic pathway to gibberellins. The two types of enzymic activity are distinct, and site-directed mutagenesis to suppress the ''ent''-kaurene synthase activity of the protein leads to build up of ''ent''-copalyl pyrophosphate.〔 Inhibition of ''ent''-kaurene synthase activity, by replacing Mg2+ in the growth medium with Ni2+, has the same effect.〔 Higher plants typically have separate proteins for ''ent''-copalyl diphosphate synthase and ''ent''-kaurene synthase,〔 although these may be associated as weakly bound dimers or enzyme complexes. Rice (''Oryza sativa'') has two distinct ''ent''-copalyl diphosphate synthases, which participate in distinct metabolic pathways. Only one ''ent''-copalyl diphosphate synthase has been isolated from a bacterial species (''Streptomyces'' sp. strain KO-3988): it is also monofunctional. As might be expected, the bifunctional enzymes from lower plants are larger (946–960 residues, 106–107 kDa) than the monofunctional enzymes from higher plants (800–867 residues, 90–98 kDa), although not by twice as much.〔(【引用サイトリンク】 url = http://www.brenda-enzymes.org/php/result_flat.php4?ecno=5.5.1.13 )〕 The independent ''ent''-kaurene synthases in higher plants, of which there may be several per species, are much more heterogenous in size, ranging 161–816 residues, 19–94 kDa. 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「Ent-Copalyl diphosphate synthase」の詳細全文を読む スポンサード リンク
|