RESUMEN
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 parallel β-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.