Thermodynamics of the hydrolysis reactions of 1,4-β-d-xylobiose, 1,4-β-d-xylotriose, d-cellobiose, and d-maltose

Tewari, Yadu B.; Lang, Brian E.; Decker, Stephen R.; Goldberg, Robert N.

doi:10.1016/j.jct.2008.05.015

Cited by 20 publications

(11 citation statements)

References 48 publications

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“…1b and d suggest that ΔH app is −3.6 kJ/mol and −2.3 kJ/mol for PCS and Avicel, respectively. This is close to the enthalpy change of hydrolysis for the β-1-4 glucosidic bond in cellobiose [38], and contributions to the measured heat flow from side reactions and intermolecular interactions therefore appear to be small even in a multicomponent and water-poor PCS sample. The reproducibility of calorimetric trials was satisfactory with an average variance (standard deviation/average of the total heat production over 18 h) of 6.8% (based on triplicate samples at ten different dosages).…”

Section: Resultssupporting

confidence: 68%

Kinetics of Enzymatic High-Solid Hydrolysis of Lignocellulosic Biomass Studied by Calorimetry

Olsen

Lumby

McFarland

et al. 2010

Appl Biochem Biotechnol

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Enzymatic hydrolysis of high-solid biomass (>10% w/w dry mass) has become increasingly important as a key step in the production of second-generation bioethanol. To this end, development of quantitative real-time assays is desirable both for empirical optimization and for detailed kinetic analysis. In the current work, we have investigated the application of isothermal calorimetry to study the kinetics of enzymatic hydrolysis of two substrates (pretreated corn stover and Avicel) at high-solid contents (up to 29% w/w). It was found that the calorimetric heat flow provided a true measure of the hydrolysis rate with a detection limit of about 500 pmol glucose s(-1). Hence, calorimetry is shown to be a highly sensitive real-time method, applicable for high solids, and independent on the complexity of the substrate. Dose-response experiments with a typical cellulase cocktail enabled a multidimensional analysis of the interrelationships of enzyme load and the rate, time, and extent of the reaction. The results suggest that the hydrolysis rate of pretreated corn stover is limited initially by available attack points on the substrate surface (<10% conversion) but becomes proportional to enzyme dosage (excess of attack points) at later stages (>10% conversion). This kinetic profile is interpreted as an increase in polymer end concentration (substrate for CBH) as the hydrolysis progresses, probably due to EG activity in the enzyme cocktail. Finally, irreversible enzyme inactivation did not appear to be the source of reduced hydrolysis rate over time.

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Section: Resultssupporting

confidence: 68%

Kinetics of Enzymatic High-Solid Hydrolysis of Lignocellulosic Biomass Studied by Calorimetry

Olsen

Lumby

McFarland

et al. 2010

Appl Biochem Biotechnol

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“…We are not aware of any experimental data on the standard free energy change, ⌬G hydrol 0 , for the conversion of Avicel (or any other type of cellulose) into cellobiose. Goldberg and co-workers (51) found that ⌬G hydrol 0 for the ␤-1,4-glycosidic bond in cellobiose was about Ϫ16 kJ/mol at room temperature and further reported that the free energy change per hydrolyzed glucosidic bond was in general quite constant in longer oligosaccharides. Based on this, we use ⌬G hydrol 0 ϭ Ϫ16 kJ/mol in the diagram below.…”

Section: Resultsmentioning

confidence: 98%

Free Energy Diagram for the Heterogeneous Enzymatic Hydrolysis of Glycosidic Bonds in Cellulose

Sørensen

Cruys-Bagger

Borch

et al. 2015

Journal of Biological Chemistry

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Background: Heterogeneous enzyme catalysis is common but has rarely been rationalized through free energy diagrams. Results: The thermodynamic properties of stable and activated cellulase complexes are reported. Conclusion:The rate of enzyme-substrate complexation is entropy-controlled, whereas dissociation is controlled by enthalpy. Significance: Supposedly, this is the first elucidation of the transition states for the complexation and dissociation steps of a cellulase.

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“…for which the standard reaction quantities are D r H m = À2.4 kJÁmol À1 , D r G m = À16.1 kJÁmol À1 , and D r S m = 46.0 JÁK À1 Ámol À1 at T = 298.15 K [111]. It is seen that reaction (82) is driven largely by a positive value of D r S m .…”

Section: Reactionmentioning

confidence: 93%

“…By using the standard formation properties for cellobiose(cr) given by Tewari et al [111] we calculate D r H m = À17.2 kJÁmol À1 , D r G m = À0.1 kJÁmol À1 , and D r S m = À57.4 JÁK À1 Ámol À1 for reaction (81) at T = 298.15 K.…”

Section: Reactionmentioning

confidence: 99%

A thermodynamic investigation of the cellulose allomorphs: Cellulose(am), cellulose Iβ(cr), cellulose II(cr), and cellulose III(cr)

Goldberg

Schliesser

Mittal

et al. 2015

The Journal of Chemical Thermodynamics

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a b s t r a c tThe thermochemistry of samples of amorphous cellulose, cellulose I, cellulose II, and cellulose III was studied by using oxygen bomb calorimetry, solution calorimetry in which the solvent was cadoxen (a cadmium ethylenediamine solvent), and with a Physical Property Measurement System (PPMS) in zero magnetic field to measure standard massic heat capacities C p;w over the temperature range T = (2 to 302) K. The samples used in this study were prepared so as to have different values of crystallinity indexes CI and were characterized by X-ray diffraction, by Karl Fischer moisture determination, and by using gel permeation chromatography to determine the weight average degree of polymerization DP w . NMR measurements on solutions containing the samples dissolved in cadoxen were also performed in an attempt to resolve the issue of the equivalency or non-equivalency of the nuclei in the different forms of cellulose that were dissolved in cadoxen. While large differences in the NMR spectra for the various cellulose samples in cadoxen were not observed, one cannot be absolutely certain that these cellulose samples are chemically equivalent in cadoxen. Equations were derived which allow one to adjust measured property values of cellulose samples having a mass fraction of water w H 2 O to a reference value of the mass fraction of water w ref . The measured thermodynamic properties (standard massic enthalpy of combustion D c H w , standard massic enthalpy of solution D sol H w , and C p;w ) were used in conjunction with the measured CI values to calculate values of the changes in the standard massic enthalpies of reactionD r H Ã w , the standard massic entropies of reaction D r S Ã w , the standard massic Gibbs free energies of reaction D r G Ã w , and the standard massic heat capacity D r C p;w , for the interconversion reactions of the pure (CI = 100) cellulose allomorphs, i.e., cellulose(am), cellulose I(cr), cellulose II(cr), and cellulose II(cr), at the temperature T = 298.15 K, the pressure p = 0.1 MPa, and w H 2 O = 0.073. The '' ⁄ '' denotes that the thermodynamic property pertains to pure cellulose allomorphs. Values of standard massic enthalpy differences D T 0 H w , standard massic entropy differences D T 0 S w , and the standard massic thermal functionwere calculated from the measured heat capacities for the cellulose samples and for the pure cellulose allomorphs. The extensive literature pertinent to the thermodynamic properties of cellulose has been summarized and, in many cases, property values have been calculated or recalculated from previously reported data. The thermodynamic property data show that cellulose(am) is the least stable of the cellulose allomorphs considered in this study. However, due to the uncertainties in the measured property values, it is not possible to use these values to order the relative stabilities of the cellulose (I, II, and III) crystalline allomorphs with a reasonable degree of certainty. Nevertheless, http://dx.

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Thermodynamics of the hydrolysis reactions of 1,4-β-d-xylobiose, 1,4-β-d-xylotriose, d-cellobiose, and d-maltose

Cited by 20 publications

References 48 publications

Kinetics of Enzymatic High-Solid Hydrolysis of Lignocellulosic Biomass Studied by Calorimetry

Kinetics of Enzymatic High-Solid Hydrolysis of Lignocellulosic Biomass Studied by Calorimetry

Free Energy Diagram for the Heterogeneous Enzymatic Hydrolysis of Glycosidic Bonds in Cellulose

A thermodynamic investigation of the cellulose allomorphs: Cellulose(am), cellulose Iβ(cr), cellulose II(cr), and cellulose III(cr)

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