Highly glucose tolerant β-glucosidase from Aspergillus unguis: NII 08123 for enhanced hydrolysis of biomass

2013 ◽  
Vol 40 (9) ◽  
pp. 967-975 ◽  
Author(s):  
Kuni Parambil Rajasree ◽  
Gincy Marina Mathew ◽  
Ashok Pandey ◽  
Rajeev Kumar Sukumaran
2021 ◽  
Author(s):  
Sushant Kumar Sinha ◽  
Maithili Datta ◽  
Supratim Datta

β-Glucosidase (EC 3.2.1.21) plays an essential role in the hydrolysis of the β-1,4 linkage of cellobiose. Accumulated glucose during saccharification leads to product inhibition of β-Glucosidase, which causes an accumulation...


2019 ◽  
Author(s):  
Sushant K Sinha ◽  
Shibashis Das ◽  
Sukanya Konar ◽  
Pradip Kr. Ghorai ◽  
Rahul Das ◽  
...  

Abstractβ-glucosidase catalyzes the hydrolysis of β-1,4 linkage between two glucose molecules in cello-oligosaccharides and is prone to inhibition by the reaction product glucose. Relieving the glucose inhibition of β-glucosidase is a significant challenge. Towards the goal of understanding how glucose interacts with β-glucosidase, we expressed in Escherichia coli, the Hore_15280 gene encoding a β-glucosidase in Halothermothrix orenii. Our results show that the enzyme is glucose tolerant, and its activity stimulated in the presence of up to 0.5 M glucose. NMR analyses show the unexpected interactions between glucose and the β-glucosidase at lower concentrations of glucose that however does not lead to enzyme inhibition. We identified non-conserved residues at the aglycone-binding and the gatekeeper site and show that increased hydrophobicity at the pocket entrance and a reduction in steric hindrances are critical towards enhanced substrate accessibility and significant improvement in activity. Analysis of structures and in combination with molecular dynamics simulations show that glucose increases the accessibility of the substrate by enhancing the structural flexibility of the active site pocket and may explain the stimulation in specific activity up to 0.5 M glucose. Such novel regulation of β-glucosidase activity by its reaction product may offer novel ways of engineering glucose tolerance.


2019 ◽  
Vol 41 (10) ◽  
pp. 1201-1211 ◽  
Author(s):  
Prajeesh Kooloth Valappil ◽  
Kuni Parambil Rajasree ◽  
Amith Abraham ◽  
Meera Christopher ◽  
Rajeev K. Sukumaran

2021 ◽  
pp. 103551
Author(s):  
Prajeesh Kooloth-Valappil ◽  
Meera Christopher ◽  
Athira Raj Sreeja-Raju ◽  
Reshma M Mathew ◽  
Rajasree Kuni-Parambil ◽  
...  

2020 ◽  
Vol 42 (12) ◽  
pp. 2759-2759
Author(s):  
Prajeesh Kooloth Valappil ◽  
Kuni Parambil Rajasree ◽  
Amith Abraham ◽  
Meera Christopher ◽  
Rajeev K. Sukumaran

Author(s):  
R. J. Barrnett ◽  
J. A. Higgins

The main products of intestinal hydrolysis of dietary triglycerides are free fatty acids and monoglycerides. These form micelles from which the lipids are absorbed across the mucosal cell brush border. Biochemical studies have indicated that intestinal mucosal cells possess a triglyceride synthesising system, which uses monoglyceride directly as an acylacceptor as well as the system found in other tissues in which alphaglycerophosphate is the acylacceptor. The former pathway is used preferentially for the resynthesis of triglyceride from absorbed lipid, while the latter is used mainly for phospholipid synthesis. Both lipids are incorporated into chylomicrons. Morphological studies have shown that during fat absorption there is an initial appearance of fat droplets within the cisternae of the smooth endoplasmic reticulum and that these subsequently accumulate in the golgi elements from which they are released at the lateral borders of the cell as chylomicrons.We have recently developed several methods for the fine structural localization of acyltransferases dependent on the precipitation, in an electron dense form, of CoA released during the transfer of the acyl group to an acceptor, and have now applied these methods to a study of the fine structural localization of the enzymes involved in chylomicron lipid biosynthesis. These methods are based on the reduction of ferricyanide ions by the free SH group of CoA.


Author(s):  
T. Baird ◽  
J.R. Fryer ◽  
S.T. Galbraith

Introduction Previously we had suggested (l) that the striations observed in the pod shaped crystals of β FeOOH were an artefact of imaging in the electron microscope. Contrary to this adsorption measurements on bulk material had indicated the presence of some porosity and Gallagher (2) had proposed a model structure - based on the hollandite structure - showing the hollandite rods forming the sides of 30Å pores running the length of the crystal. Low resolution electron microscopy by Watson (3) on sectioned crystals embedded in methylmethacrylate had tended to support the existence of such pores.We have applied modern high resolution techniques to the bulk crystals and thin sections of them without confirming these earlier postulatesExperimental β FeOOH was prepared by room temperature hydrolysis of 0.01M solutions of FeCl3.6H2O, The precipitate was washed, dried in air, and embedded in Scandiplast resin. The sections were out on an LKB III Ultramicrotome to a thickness of about 500Å.


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