改性丙烯酸酯乳液的研究进展

综述了近年来我国改性丙烯酸酯乳液的研究进展,重点介绍了我国有机硅改性丙烯酸酯乳液、有机氟改性丙烯酸酯乳液、环氧树脂改性丙烯酸酯乳液、纳米SiO_2改性丙烯酸酯乳液、苯乙烯改性丙烯酸酯乳液的最新研究现状,最后指出了我国改性丙烯酸酯乳液的发展方向。     

21世纪精细化工的发展

概述当前精细化工的范畴和部分精细化学品的发展状况,并指出了21世纪精细化工发展的方向。     

Acetyl Coenzyme A Analogues as Rationally Designed Inhibitors of Citrate Synthase

In this study, we probed the inhibition of pig heart citrate synthase (E.C. 4.1.3.7) by synthesising seven analogues either designed to mimic the proposed enolate intermediate in this enzyme reaction or developed from historical inhibitors. The most potent inhibitor was fluorovinyl thioether 9 (K_i=4.3 μm ), in which a fluorine replaces the oxygen atom of the enolate. A comparison of the potency of 9 with that of its non-fluorinated vinyl thioether analogue 10 (K_i=68.3 μm ) revealed a clear “fluorine effect” favouring 9 by an order of magnitude. The dethia analogues of 9 and 10 proved to be poor inhibitors. A methyl sulfoxide analogue was a moderate inhibitor (K_i=11.1 μm ), thus suggesting hydrogen bonding interactions in the enolate site. Finally, E and Z propenoate thioether isomers were explored as conformationally constrained carboxylates, but these were not inhibitors. All compounds were prepared by the synthesis of the appropriate pantetheinyl diol and then assembly of the coenzyme A structure according to a three-enzyme biotransformation protocol. A quantum mechanical study, modelling both inhibitors 9 and 10 into the active site indicated short CF ⋅⋅⋅ H contacts of ≈2.0 Å, consistent with fluorine making two stabilising hydrogen bonds, and mimicking an enolate rather than an enol intermediate. Computation also indicated that binding of 9 to citrate synthase increases the basicity of a key aspartic acid carboxylate, which becomes protonated.