Bioresources and Bioprocessing (Oct 2018)
Structural and functional properties of pectin and lignin–carbohydrate complexes de-esterases: a review
Abstract
Abstract Biological conversion of plant biomass into commercially valuable products is one of the highly studied subjects in the last two decades. Studies were continuously being conducted to understand and develop efficient enzymes for the breakdown and conversion of plant cell-wall components into valuable commercial products. Naturally, plant cell-wall components are differentially esterified to protect from the invading microorganisms. However, during the process of evolution, microorganisms have developed special set of enzymes to de-esterify the plant cell-wall components. Among the carbohydrate-active enzymes (CAZy), carbohydrate esterases stand first during the process of enzymatic conversion of plant biomass, as these enzymes de-esterify the plant biomass and make it accessible for the hydrolytic enzymes such as cellulases, hemicellulases, ligninolytic and pectinases. In this article, we have extensively discussed about the structural and functional properties of pectin methyl esterases, feruloyl, cinnamoyl and glucuronoyl esterases which are required for the de-esterification of pectin and lignin–carbohydrate complexes. Pectin esterases are classified among CE8, CE12, CE13 and CE15 carbohydrate esterase class of CAZy database. Whereas, lignin–carbohydrate complex de-esterifying enzymes are classified among CE1 (feruloyl esterase) and CE15 (glucuronoyl esterase) classes. Understanding the structural and functional abilities of pectin and lignin–carbohydrate esterases will significantly aid in developing efficient class of de-esterases for reducing the recalcitrant nature of plant biomass. These efficient de-esterases will have various applications including pretreatment of plant biomass, food, beverage, pulp and paper, textile, pharmaceutical and biofuel industries.
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