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Difference between revisions of "Enzymatic processes"
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==== Cellulases ==== | ==== Cellulases ==== | ||
Cellulases are one of the key enzymes in biomass hydrolysis. Cellulases are a family of enzymes that synergistically act on cellulose to hydrolyze it to its monomers. Cellulases acts on the ß-1,4-glycosidic linkages in cellulose. The complete hydrolysis of cellulose is mediated by combination of three main cellulases, namely endoglucanases [https://enzyme.expasy.org/EC/3.2.1.14 (EC 3.2.14)], exoglucanases [https://enzyme.expasy.org/EC/3.2.1.91 (EC 3.2.1.91)], and glycosidase [https://enzyme.expasy.org/EC/3.2.1.21 (EC 3.2.1.21)]. ''T. reesei''-based cellulases have been the focus of research for the past several years and are widely used in laboratory- as well as pilot-scale studies for bioethanol application. Most commercially accessible enzymes for biomass hydrolysis are actually cocktails of cellulases from ''Trichoderma'' or ''Aspergillus'' supplemented with ß-glucosidases from other sources. | |||
==== Hemicellulases ==== | ==== Hemicellulases ==== | ||
Hemicellulose consists of a mixture of glucose and sugar monomers. Xylan is the most abundant hemicellulose-containing pentose sugars, such as xylose. The enzyme xylanase helps to catalyze the hydrolysis of xylan. Hydrolysis of xylan is mediated by the action of multiple xylanases (i.e., endoxylanases and exoxylanases). Commercially, xylanases are produced from ''T. reesei'', ''A. niger'', ''humicola insolens'', and ''Bacillus'' sp. | |||
==== Pectinases ==== | ==== Pectinases ==== | ||
Pectinase is a complex enzyme that degrades the pectin present in lignocellulosic biomass. Pectin is a polymer of α-1,4-linked D-galacturonic acid. This enzyme breaks down polygalacturonic acid (GalA) into a monomeric unit by opening glycosidic linkages. It helps the softening of biomass and therefore aids in the hydrolysis of biomass. | |||
==== Other accessory enzymes ==== | ==== Other accessory enzymes ==== | ||