Bose Ishani, Bahrami Foroogh, Zhao Yan
Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, USA.
Mater Today Chem. 2023 Jun;30. doi: 10.1016/j.mtchem.2023.101576. Epub 2023 May 18.
Ester is one of the most prevalent functional groups in natural and man-made products. Natural esterases hydrolyze nonactivated alkyl esters readily but artificial esterases generally use highly activated -nitrophenyl esters as substrates. We report synthetic esterases constructed through molecular imprinting in cross-linked micelles. The water-soluble nanoparticle catalysts contain a thiouronium cation to mimic the oxyanion hole and a nearby base to assist the hydrolysis. Whereas this catalytic motif readily affords large rate acceleration for the hydrolysis of -nitrophenyl hexanoate, nonactivated cyclopentyl hexanoate demands catalytic groups that can generate a strong nucleophile (hydroxide) in the active site. The hydroxide is stabilized by the protonated base when the external solution is at pH 7, enabling the hydrolysis of activated and nonactivated esters under neutral conditions.
酯是天然和人造产品中最普遍存在的官能团之一。天然酯酶能轻易水解未活化的烷基酯，但人工酯酶通常使用高度活化的对硝基苯酯作为底物。我们报道了通过在交联胶束中进行分子印迹构建的合成酯酶。这种水溶性纳米颗粒催化剂含有一个硫脲阳离子以模拟氧阴离子空穴，以及一个附近的碱来协助水解。虽然这种催化基序能轻易地大幅加速己酸对硝基苯酯的水解，但未活化的己酸环戊酯则需要能在活性位点产生强亲核试剂（氢氧根）的催化基团。当外部溶液的pH值为7时，质子化的碱会使氢氧根稳定，从而能够在中性条件下水解活化和未活化的酯。
