果胶甲酯酶的结构与功能研究进展

Research progress in structure and function of pectin methylesterase

果胶甲酯酶(PME)是一种重要的果胶酶,其水解果胶中的甲酯基从而释放甲醇并降低果胶的甲酯化程度。目前在食品加工、茶饮料、造纸等生产工艺中有着广泛的应用前景。随着对PME的深入研究,已报道了几种不同来源的酶晶体结构,对这些已获得的晶体结构进行分析发现,PME属于右手平行β-螺旋结构,其催化残基为2个保守的天冬氨酸和1个谷氨酰胺残基,并且在催化过程中分别起到了一般酸碱、亲核试剂以及稳定中间体的作用。同时对其底物特异性进行分析,初步了解其底物与活性位点的识别机制。文中针对这几个相关方面进行了系统的综述。

Pectin methylesterase(PME)is an important pectinase that hydrolyzes methyl esters in pectin to release methanol and reduce the degree of methylation of pectin.At present,it has broad application prospects in food processing,tea beverage,paper making and other production processes.With the in-depth study of PME,the crystal structures with different sources have been reported.Analysis of these resolved crystal structures reveals that PME belongs to the right-hand parallelβ-helix structure,and its catalytic residues are two aspartic acids and a glutamine,which play the role of general acid-base,nucleophile and stable intermediate,in the catalytic process.At the same time,the substrate specificity is analyzed to understand the recognition mechanism of the substrate and active sites.This paper systematically reviews these related aspects.