Role of thermophilic cellulases and organisms in the conversion of biomass to biofuels

Goswami, Shubhasish; Nath, Praveen; Datta, Supratim

doi:10.1016/b978-0-323-90274-8.00010-1

Cited by 3 publications

(2 citation statements)

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“…The enzyme is endowed with favorable characteristics as its yield per liter culture is 70 mg, it is easily storable for up to 2 months at 4 °C and has a melting temperature of 73 °C at pH 5.5. Even though MAO Tb was found in an obligated anaerobic bacteria order [32], its presteady‐state kinetics showed that the enzyme can act as a true flavoprotein oxidase as it is efficient in using dioxygen as electron acceptor at atmospheric conditions. Interestingly, the affinity for molecular oxygen was found to be very poor (high K M value).…”

Section: Discussionmentioning

confidence: 99%

Discovery and structural characterization of a thermostable bacterial monoamine oxidase

Santema,

Basile,

Binda

et al. 2023

The FEBS Journal

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Monoamine oxidases (MAOs) are pivotal regulators of neurotransmitters in mammals, while microbial MAOs have been shown to be valuable biocatalysts for enantioselective synthesis of pharmaceutical compounds or precursors thereof. For extending the knowledge on how MAOs function at molecular level and in order to provide more biocatalytic tools, we set out to identify and study a robust bacterial variant: a MAO from the thermophile Thermoanaerobacterales bacterium (MAOTb). MAOTb is highly thermostable with melting temperatures above 73 0C and is well expressed in Escherichia coli. Substrate screening revealed that the oxidase is most efficient with n‐alkylamines with n‐heptylamine being the best substrate. Pre‐steady state kinetic analysis shows that reduced MAOTb rapidly reacts with molecular oxygen confirming that it is a bona fide oxidase. The crystal structure of MAOTb was resolved at 1.5 Å and showed an exceptionally high similarity with the two human monoamine oxidases, MAO A and MAO B. The active site of MAOTb resembles mostly the architecture of human MAO A, including the cysteinyl protein‐FAD linkage. Yet, the bacterial MAO lacks a C‐terminal extension found in human MAOs, which explains why it is expressed and purified as soluble protein, while the mammalian counterparts are anchored to the membrane through an α‐helix. MAOTb also displays a slightly different active site access tunnel, which may explain the specificity towards long aliphatic amines. Being an easy to express, thermostable enzyme, for which a high‐resolution structure was elucidated, this bacterial MAO may develop into a valuable biocatalyst for synthetic chemistry or biosensing.

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Section: Discussionmentioning

confidence: 99%

Discovery and structural characterization of a thermostable bacterial monoamine oxidase

Santema,

Basile,

Binda

et al. 2023

The FEBS Journal

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“…Finally, BG's cleave the β-1,4-glycosidic bonds to generate glucose that microbes can ferment to make biofuels. [1][2][3] Most β-glucosidases that are reported in the literature are characterized by the model chromogenic substrate, p-Nitrophenyl beta-D-glucopyranoside (pNPGlc). Previously several attempts have been made to increase the activity of β-glucosidases.…”

Section: Introductionmentioning

confidence: 99%

Rational engineering of a β-glucosidase (H0HC94) from glycosyl family I (GH1) to improve catalytic performance on cellobiose

Sengupta¹,

Chanda²,

Manna³

et al. 2022

Preprint

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The conversion of lignocellulosic feedstocks by cellulases to glucose is a critical step in biofuel production. β-glucosidases catalyze the final step in cellulose breakdown, producing glucose, and is often the rate-limiting step in biomass hydrolysis. Rationally engineering previously characterized enzymes may be one strategy to increase catalytic activity and the efficiency of cellulose hydrolysis. The specific activity of most natural and engineered β-glucosidase is higher on the artificial substrate p-Nitrophenyl β-D-glucopyranoside (pNPGlc) than on the natural substrate, cellobiose. Based on our hypothesis of increasing catalytic activity by reducing the interaction of residues present near the active site tunnel entrance with glucose without disturbing any existing interactions with cellobiose, we report an engineered β-glucosidase (Q319A H0HC94) with a 1.8-fold specific activity increase (366.3 ± 36 μmol/min/mg), an almost 1.5-fold increase in kcat (340.8 ± 27 s-1), and a 3-fold increase in Q319A H0HC94 cellobiose specificity (236.65 mM-1 s-1) over HOHC94. Molecular dynamic simulations and protein structure network analysis indicate that Q319A significantly increased the dynamically stable communities and hub residues, leading to a change in enzyme conformation and higher enzymatic activity. This study shows the impact of rational engineering of non-conserved residue to increase β-glucosidase substrate accessibility and enzyme specificity.

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Perspective on Lignin Conversion Strategies That Enable Next Generation Biorefineries

Shrestha,

Goswami,

Banerjee

et al. 2024

ChemSusChem

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The valorization of lignin, a currently underutilized component of lignocellulosic biomass, has attracted attention to promote a stable and circular bioeconomy. Successful approaches including thermochemical, biological, and catalytic lignin depolymerization have been demonstrated, enabling opportunities for lignino‐refineries and lignocellulosic biorefineries. Although significant progress in lignin valorization has been made, this review describes unexplored opportunities in chemical and biological routes for lignin depolymerization and thereby contributes to economically and environmentally sustainable lignin‐utilizing biorefineries. This review also highlights the integration of chemical and biological lignin depolymerization and identifies research gaps while also recommending future directions for scaling processes to establish a lignino‐chemical industry.

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Role of thermophilic cellulases and organisms in the conversion of biomass to biofuels

Cited by 3 publications

References 173 publications

Discovery and structural characterization of a thermostable bacterial monoamine oxidase

Discovery and structural characterization of a thermostable bacterial monoamine oxidase

Rational engineering of a β-glucosidase (H0HC94) from glycosyl family I (GH1) to improve catalytic performance on cellobiose

Perspective on Lignin Conversion Strategies That Enable Next Generation Biorefineries

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