scholarly journals Determination of Surface Accessibility of the Cellulose Substrate According to Enzyme Sorption

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1201 ◽  
Author(s):  
Ekaterina M. Podgorbunskikh ◽  
Aleksey L. Bychkov ◽  
Oleg I. Lomovsky
Keyword(s):  
Enzymatic Hydrolysis ◽  
Mechanical Activation ◽  
Surface Area ◽  
Initial Rate ◽  
Plant Biomass ◽  
Inorganic Compounds ◽  
Cellulolytic Enzymes ◽  
Surface Accessibility ◽  
Cellulose Substrate ◽  
Rate Of Hydrolysis

As a heterogeneous process, enzymatic hydrolysis depends on the contact area between enzymes and the cellulose substrate. The surface area of a substrate is typically evaluated through the sorption of gases (nitrogen, argon, or water vapor) or sorption of high-molecular-weight pigments or proteins. However, lignocellulosic biomass uninvolved in the reaction because of inefficient binding or even the complete inhibition of the enzymes on the surface consisting of lignin or inorganic compounds is erroneously taken into account under these conditions. The initial rate of enzymatic hydrolysis will directly depend on the number of enzymes efficiently sorbed onto cellulose. In this study, the sorption of cellulolytic enzymes was used to evaluate the surface accessibility of the cellulose substrate and its changes during mechanical pretreatment. It was demonstrated that for pure cellulose, mechanical activation did not alter the chemical composition of the surface and the initial rate of hydrolysis increased, which was inconsistent with the data on the thermal desorption of nitrogen. New active cellulose sorption sites were shown to be formed upon. the mechanical activation of plant biomass (wheat straw), and the ultimate initial rate of hydrolysis corresponding to saturation of the accessible surface area with enzyme molecules was determined.

scholarly journals Generation of highly amenable cellulose-Iβ via selective delignification of rice straw using a reusable cyclic ether-assisted deep eutectic solvent system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chiranjeevi Thulluri ◽  
Ravi Balasubramaniam ◽  
Harshad Ravindra Velankar
Keyword(s):  
Enzymatic Hydrolysis ◽  
Rice Straw ◽  
Deep Eutectic Solvent ◽  
Solvent System ◽  
Cyclic Ether ◽  
Cellulolytic Enzymes ◽  
Ammonium Bromide ◽  
Selective Delignification ◽  
Cellulose Iβ ◽  
Hydrolysis Of

AbstractCellulolytic enzymes can readily access the cellulosic component of lignocellulosic biomass after the removal of lignin during biomass pretreatment. The enzymatic hydrolysis of cellulose is necessary for generating monomeric sugars, which are then fermented into ethanol. In our study, a combination of a deep eutectic (DE) mixture (of 2-aminoethanol and tetra-n-butyl ammonium bromide) and a cyclic ether (tetrahydrofuran) was used for selective delignification of rice straw (RS) under mild conditions (100 °C). Pretreatment with DE-THF solvent system caused ~ 46% delignification whereas cellulose (~ 91%) and hemicellulose (~ 67%) recoveries remained higher. The new solvent system could be reused upto 10 subsequent cycles with the same effectivity. Interestingly, the DE-THF pretreated cellulose showed remarkable enzymatic hydrolysability, despite an increase in its crystallinity to 72.3%. Contrary to conventional pretreatments, we report for the first time that the enzymatic hydrolysis of pretreated cellulose is enhanced by the removal of lignin during DE-THF pretreatment, notwithstanding an increase in its crystallinity. The current study paves way for the development of newer strategies for biomass depolymerization with DES based solvents.

scholarly journals Organosolv pretreatment assisted by carbocation scavenger to mitigate surface barrier effect of lignin for improving biomass saccharification and utilization

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Qiulu Chu ◽  
Wenyao Tong ◽  
Jianqiang Chen ◽  
Shufang Wu ◽  
Yongcan Jin ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Surface Area ◽  
Cellulose Hydrolysis ◽  
Syringic Acid ◽  
Fermentable Sugars ◽  
Surface Barrier ◽  
Textile Dye ◽  
Barrier Effect ◽  
Biomass Saccharification ◽  
Carbocation Scavenger

Abstract Background Ethanol organosolv (EOS) pretreatment is one of the most efficient methods for boosting biomass saccharification as it can achieve an efficient fractionation of three major constituents in lignocellulose. However, lignin repolymerization often occurs in acid EOS pretreatment, which impairs subsequent enzymatic hydrolysis. This study investigated acid EOS pretreatment assisted by carbocation scavenger (2-naphthol, 2-naphthol-7-sulfonate, mannitol and syringic acid) to improve biomass fractionation, coproduction of fermentable sugars and lignin adsorbents. In addition, surface barrier effect of lignin on cellulose hydrolysis was isolated from unproductive binding effect of lignin, and the analyses of surface chemistry, surface morphology and surface area were carried out to reveal the lignin inhibition mitigating effect of various additives. Results Four different additives all helped mitigate lignin inhibition on cellulose hydrolysis in particular diminishing surface barrier effect, among which 2-naphthol-7-sulfonate showed the best performance in improving pretreatment efficacy, while mannitol and syringic acid could serve as novel green additives. Through the addition of 2-naphthol-7-sulfonate, selective lignin removal was increased up to 76%, while cellulose hydrolysis yield was improved by 85%. As a result, 35.78 kg cellulose and 16.63 kg hemicellulose from 100 kg poplar could be released and recovered as fermentable sugars, corresponding to a sugar yield of 78%. Moreover, 22.56 kg ethanol organosolv lignin and 17.53 kg enzymatic hydrolysis residue could be recovered as lignin adsorbents for textile dye removal, with the adsorption capacities of 45.87 and 103.09 mg g−1, respectively. Conclusions Results in this work indicated proper additives could give rise to the form of less repolymerized surface lignin, which would decrease the unproductive binding of cellulase enzymes to surface lignin. Besides, the supplementation of additives (NS, MT and SA) resulted in a simultaneously increased surface area and decreased lignin coverage. All these factors contributed to the diminished surface barrier effect of lignin, thereby improving the ease of enzymatic hydrolysis of cellulose. The biorefinery process based on acidic EOS pretreatment assisted by carbocation scavenger was proved to enable the coproduction of fermentable sugars and lignin adsorbents, allowing the holistic utilization of lignocellulosic biomass for a sustainable biorefinery. Graphic abstract

scholarly journals Influence of Me2SO and incubation time on papain activity studied using fluorogenic substrates.

2001 ◽  
Vol 48 (4) ◽  
pp. 995-1002 ◽  
Author(s):  
M Szabelski ◽  
K Stachowiak ◽  
W Wiczk
Keyword(s):  
Incubation Time ◽  
Active Sites ◽  
Initial Rate ◽  
Substrate Binding ◽  
Rapid Decrease ◽  
Fluorogenic Substrates ◽  
Binding Process ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Papain activity in a buffer containing Me2SO was studied using fluorogenic substrates. It was found that the number of active sites of papain decreases with increasing Me2SO concentration whereas the incubation time, in a buffer containing 3% Me2SO does not affect the number of active sites. However, an increase of papain incubation time in the buffer with 3% Me2SO decreased the initial rate of hydrolysis of Z-Phe-Arg-Amc as well as Dabcyl-Lys-Phe-Gly-Gly-Ala-Ala-Edans. Moreover, an increase of Me2SO concentration in working buffer decreased the initial rate of papain-catalysed hydrolysis of both substrates. A rapid decrease of the initial rate (by up to 30%) was observed between 1 and 2% Me2SO. Application of the Michaelis-Menten equation revealed that at the higher Me2SO concentrations the apparent values of k(cat)/Km decreased as a result of Km increase and kcat decrease. However, Me2SO changed the substrate binding process more effectively (Km) than the rate of catalysis k(cat).

scholarly journals Accumulation of dry substances in hydrolysate during the processing of barley malt sprouts with a celluloid enzyme complex

2021 ◽  
Vol 32 ◽  
pp. 03005
Author(s):  
O. N. Vetrova ◽  
O. Y. Eremina ◽  
N. V. Seregina ◽  
N. V. Shuldeshova
Keyword(s):  
Enzymatic Hydrolysis ◽  
Substrate Concentration ◽  
Enzyme Preparation ◽  
Mutual Influence ◽  
Matter Content ◽  
Cellulolytic Enzymes ◽  
Dry Matter Content ◽  
Barley Malt ◽  
Hydrolysis Process ◽  
Parameter Values

The article presents the results of a study of the enzymatic hydrolysis of barley malt sprouts by cellulolytic enzymes. The influence of the process parameters (temperature, substrate concentration, concentration of the enzyme preparation, duration of the process) on the output of dry substances in the hydrolysate is shown. The results of the experiments were presented by a mathematical model of the process and graphically-in the form of surface projections reflecting the mutual influence of each possible pair of factors on the dry matter content in the hydrolysate. It is found that all the studied factors have an effect on the accumulation of dry substances in the hydrolysate. As a result of optimization the parameters of the enzymatic hydrolysis process, the following parameter values were obtained: temperature - 50 ˚С, duration of enzymatic hydrolysis-89 min, substrate concentration - 0.37 (hydromodule 1:10), concentration of the enzyme preparation - 0.05 %.

scholarly journals Michaelis-Menten Kinetic Parameters of Coconut Coir Enzymatic Hydrolysis

2015 ◽  
Vol 9 (7) ◽  
pp. 30 ◽  
Author(s):  
Akbarningrum Fatmawati ◽  
Rudy Agustriyanto
Keyword(s):  
Enzymatic Hydrolysis ◽  
Kinetic Parameters ◽  
Alternative Energy ◽  
Initial Rate ◽  
Biofuel Production ◽  
Concentration Data ◽  
Maximum Reaction Rate ◽  
Initial Substrate ◽  
Coconut Coir ◽  
Menten Kinetic

The limitation of fossil oil reserves and environmental pollution has been current problems that need to be solved. Biofuels such as ethanol can be alternative energy source that can reduce demand on fossil fuel and environmental problem. Food wastes such as coconut coirs are abundant and contain carbohydrate which can be used as the substrate for biofuel production. Pretreatment and hydrolysis are important stages which have to be applied on such lignocellulose materials before fermentation process to produce biofuel. This article presents Michaelis-Menten kinetic parameters for coconut coir enzymatic hydrolysis. Coconut coirs collected from several local markets in Surabaya were subjected to alkaline pretreatment using 11% sodium hydroxide solution at 121oC. Hydrolysis steps were carried out using commercial enzymes at various initial substrate concentrations. The hydrolysis conditions were at 50oC and pH 4.8. The concentrations of reducing sugar produced in the reactions were measured at certain time intervals. Initial rate of reactions of each reaction batch were then determined. Finally, kinetic parameters of Michaelis-Menten model for enzymatic reaction were determined by fitting the initial rate of reactions and initial substrate concentration data. From nonlinear fitting, the maximum reaction rate (Vm) is 4.9´104 1/h and the value of KM is 4,195 mg/L.

scholarly journals Kinetics of GTP hydrolysis during the assembly of chick brain MAP2-tubulin microtubule protein

1991 ◽  
Vol 277 (1) ◽  
pp. 239-243 ◽  
Author(s):  
R G Burns
Keyword(s):  
Initial Rate ◽  
Molar Concentration ◽  
Microtubule Assembly ◽  
Chick Brain ◽  
Gtp Hydrolysis ◽  
Microtubule Protein ◽  
Rate Of Hydrolysis ◽  
Kinetics Of

The kinetics of GTP hydrolysis during microtubule assembly have been examined using chick brain MAP2-tubulin microtubule protein in a NaCl-supplemented buffer. The elongating microtubules terminate in a ‘GTP cap’, since the kinetics of GTP hydrolysis are slower than those of subunit addition. GTP hydrolysis is (a) stoichiometric, (b) occurs as a vectorial wave as the initial rate of hydrolysis is proportional to the molar concentration of microtubule ends and not to the initial rate of subunit addition, and (c) either does not occur, or occurs only at a much lower rate, in the terminal subunits.

scholarly journals Reduction of surface area of lignin improves enzymatic hydrolysis of cellulose from hydrothermally pretreated wheat straw

RSC Advances ◽  
2014 ◽  
Vol 4 (69) ◽  
pp. 36591-36596 ◽  
Author(s):  
M. H. Sipponen ◽  
V. Pihlajaniemi ◽  
O. Pastinen ◽  
S. Laakso
Keyword(s):  
Enzymatic Hydrolysis ◽  
Wheat Straw ◽  
Surface Area ◽  
Lignin Content ◽  
Cellulose Conversion ◽  
Enzymatic Hydrolysis Of Cellulose ◽  
Hydrolysis Of Cellulose ◽  
Pretreated Wheat Straw ◽  
Hydrolysis Of

24 h enzymatic hydrolysis (15 FPU g−1) of solid residues from wheat straw autohydrolysis. Cellulose conversion as a function of lignin content (left) or lignin surface area (right) in solid residues.

Innovative Deconstruction of Biomass Induced by Dry Chemo-Mechanical Activation: Impact on Enzymatic Hydrolysis and Energy Efficiency

2016 ◽  
Vol 4 (5) ◽  
pp. 2689-2697 ◽  
Author(s):  
C. Loustau-Cazalet ◽  
C. Sambusiti ◽  
P. Buche ◽  
A. Solhy ◽  
E. Bilal ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Enzymatic Hydrolysis ◽  
Mechanical Activation
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