LPMO IN BIOMASS CONVERSION
Written by – Namruta Shervegar
The derived product from non-edible biomass is viewed as crucial for establishing a sustainable bio-based economy for the future. The nature of lignocellulose being inert makes it tremendously difficult for its breakdown to fuels & other compounds. For decades, the recalcitrant polysaccharides such as chitin and cellulose and their ezymatic conversion was rely on synergistic action of hydrolytic enzymes. Consortia of enzymes can be used in biorefinery for lignocellulose deconstruction but until recently their cost was considered as high. Lytic polysaccharide monooxygenases (LPMOs) these enzyme promise for further process improvements as these enzymes are able to boost up the activity of biomass-degrading enzyme consortia.
LPMO takes part in the process of lignocellulose deconstruction by catalyzing the cleavage of insoluble polysaccharide utilizing a mechanism which involves the involvement of molecular oxygen and electron donor. For more than a decade, LPMOs were annotated as a family of 61 glycoside hydrolase (GH61s) or family of 33-carbohydrate binding modules (CBM33s).These enzymes have an unsual surface exposed active site with the tightly attached Cu ion that catalyses the regioselectivity hydroxylation of crystalline cellulose, leading to glycosidic bond cleavage. LPMOs are the enzymes derived from bacterial AA10 and fungal AA9.LPMOs general core includes a distorted immunoglobin like beta sandwich fold consiting of two antiparallel beta strands connected by loops with a number of alpha insertions. This enzymes is copper dependent oxygenases. Oxidation of cellulose by LPMO is thought to produce either lactone at the reducing end of glucose that can spontaneously or enzymatically to aldonic acid or 4-keto aldose at the non reducing end that can futhur oxidized to a geminal diol.
It can be concluded that Lytic polysaccharide monooxygenses are the new upcoming enzymes derived from microorganism that have potential use in the field of biofuels as compared to the products gained by consortia of hydrolytic enzymes.
- Aachmann et al, “ Lytic Polysaccharide monooxygensae” Encyclopedia of Inorganic and Bioinorganic Chemistry 15 march 2015
- Vermaan et al,” Effects of lytic polysaccharide monooxygenase oxidation on cellulose structure and binding of oxidized cellulose oligomers to cellulases”, The journal of physical chemistry. 21 May 2015
- Hemsworth et al, Recent insights into copper-containing lytic polysaccharide mono-oxygenases October 2013
- Beeson et al “Cellulose Degradation by Polysaccharide Monooxygenases”Annual review of biochemistry 84: 923-946 June 2015