Catalysis by Orotidine 5′-Monophosphate Decarboxylase: Effect of 5-Fluoro and 4′-Substituents on the Decarboxylation of Two-Part Substrates
作者:Bogdana Goryanova、Krisztina Spong、Tina L. Amyes、John P. Richard
DOI:10.1021/bi301650d
日期:2013.1.22
identical destabilizations of the transitionstate for the unactivated decarboxylation of 2.9 kcal/mol. By contrast, the 4′-CH3 group of 5′-dFO and the 4′-CH2OH group of orotidine result in very different 4.7 and 8.3 kcal/mol destabilizations of the transitionstate for the phosphite-activated decarboxylation. Here, the destabilizing effect of the 4′-CH3 substituent at 5′-dFO is masked by the rate-limiting
据报道,合成了具有增强脱羧反应性的天然底物乳清酸 5'-单磷酸酯 ( OMP )的两种新型截短类似物,用于乳清酸 5'-单磷酸脱羧酶 (OMPDC):1-(β- d-赤呋喃糖基)-5-氟乳清酸(FEO)和5'-脱氧-5- fluoroorotidine(5 ' -dFO)。OMPDC 催化的FEO (10 M –1 s –1 ) 和 1-(β- d -赤呋喃糖基) 乳清酸 ( EO , 0.026 M –1 s –1 )脱羧的二级速率常数比较) 表明通过与FEO的 5-F 取代基相互作用,乙烯基碳负离子过渡态稳定了 3.5 kcal/mol 。OMPDC 催化的FEO和EO脱羧均被外源性亚磷酸酯二价阴离子 (HPO 3 2– )激活,但 5-F 取代基仅导致FEO亚磷酸酯活化反应的过渡态稳定 0.8 kcal 。这为亚磷酸酯活化的 OMPDC 催化的FEO反应提供了强有力的证据。不受酶结合
COOK, A. F.
作者:COOK, A. F.
DOI:——
日期:——
US4071680A
申请人:——
公开号:US4071680A
公开(公告)日:1978-01-31
MW-assisted Er(OTf)3-catalyzed mild cleavage of isopropylidene acetals in Tricky substrates
Erbium(III) trifluoromethane sulfonate is proposed as a very gentle Lewis acid catalyst in a MW-assisted chemoselective method for the cleavage of isopropylideneacetals in awkward substrates by using pure water as the solvent.