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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

An Arabinoxylan Extracted from Corn Grain Is Inhibitory to Cellulase Activity

The maize seed expression system is a powerful platform for recombinant protein production. It has been utilized for high-yield production of industrial cellulases such as endo-1,4-b-Dglucanase (E1) and 1,4-b-D-glucan cellobiohydrolases (CBHI & CBHII). However, inhibitory compounds that could significantly reduce the cellulolytic efficiency were detected even in purified E1 and CBHII samples. After several steps of purification and analysis, the inhibitory compound found in the purified E1 sample had characteristics consistent with a thermostable polysaccharide with a molecular size over 10 kDa. Further polysaccharide analysis confirmed the molecular size of the detected polysaccharide and suggested that it is an arabinoxylan with a high arabinose/xylose ratio. Even though the strict column purification process should have removed water soluble non-protein molecules during protein purification, the inhibitor remained. Here, a possible explanation is that recombinant cellulase can bind to the inhibitor, carry it through all purification steps and finally release it when denatured by heat.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Comprehensive characterization of non-cellulosic recalcitrant cell wall carbohydrates in unhydrolyzed solids from AFEX-pretreated corn stover

Inefficient carbohydrate conversion has been an unsolved problem for various lignocellulosic biomass pretreatment technologies, including AFEX, dilute acid, and ionic liquid pretreatments. Previous work has shown 22% of total carbohydrates are typically unconverted, remaining as soluble or insoluble oligomers after hydrolysis (72 h) with excess commercial enzyme loading (20 mg enzymes/g biomass). Nearly one third (7 out of 22%) of these total unconverted carbohydrates are present in unhydrolyzed solid (UHS) residues. The presence of these unconverted carbohydrates leads to a considerable sugar yield loss, which negatively impacts the overall economics of the biorefinery. Current commercial enzyme cocktails are not effective to digest specific cross-linkages in plant cell wall glycans, especially some of those present in hemicelluloses and pectins. Thus, obtaining information about the most recalcitrant non-cellulosic glycan cross-linkages becomes a key study to rationally improve commercial enzyme cocktails, by supplementing the required enzyme activities for hydrolyzing those unconverted glycans.

Biotechnology & Applied Microbiology↗