Abe Ikuro, Watanabe Tatsuya, Morita Hiroyuki, Kohno Toshiyuki, Noguchi Hiroshi
School of Pharmaceutical Sciences and the COE 21 Program, University of Shizuoka, Shizuoka 422-8526, Japan.
Org Lett. 2006 Feb 2;8(3):499-502. doi: 10.1021/ol052912h.
[reaction: see text]. Chalcone synthase (CHS) is a plant-specific type III polyketide synthase catalyzing condensation of 4-coumaroyl-CoA with three molecules of malonyl-CoA. Surprisingly, it was demonstrated that S338V mutant of Scutellaria baicalensis CHS produced octaketides SEK4/SEK4b from eight molecules of malonyl-CoA. Further, the octaketides-forming activity was dramatically increased in a CHS triple mutant (T197G/G256L/S338T). The functional conversion is based on the simple steric modulation of a chemically inert residue lining the active-site cavity.
[反应：见正文]。查尔酮合酶（CHS）是一种植物特有的III型聚酮合酶，催化4-香豆酰辅酶A与三分子丙二酰辅酶A的缩合反应。令人惊讶的是，已证明黄芩CHS的S338V突变体从八分子丙二酰辅酶A产生八酮化合物SEK4/SEK4b。此外，在CHS三重突变体（T197G/G256L/S338T）中，八酮化合物形成活性显著增加。这种功能转换基于活性位点腔内化学惰性残基的简单空间调节。
