The Role of Evolving Interfacial Substrate Properties on Heterogeneous Cellulose Hydrolysis Kinetics

AbstractInterfacial enzyme reactions require formation of an enzyme-substrate complex at the surface of a heterogeneous substrate, but often multiple modes of enzyme binding and types of binding sites complicate analysis of their kinetics. Excess of heterogeneous substrate is often used as a justification to model the substrate as unchanging; but using the study of the enzymatic hydrolysis of insoluble cellulose as an example, we argue that reaction rates are dependent on evolving substrate interfacial properties. We hypothesize that the relative abundance of binding sites on cellulose where hydrolysis can occur (productive binding sites) and binding sites where hydrolysis cannot be initiated or is inhibited (non-productive binding sites) contribute to rate limitations. We show that the initial total number of productive binding sites (the productive binding capacity) determines the magnitude of the initial burst phase of cellulose hydrolysis, while productive binding site depletion explains overall hydrolysis kinetics. Furthermore, we show that irreversibly bound surface enzymes contribute to the depletion of productive binding sites. Our model shows that increasing the ratio of productive- to non-productive binding sites promotes hydrolysis, while maintaining an elevated productive binding capacity throughout conversion is key to preventing hydrolysis slowdown.

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Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.12.254 ◽

2016 ◽

Vol 12 ◽

pp. 2588-2601 ◽

Cited By ~ 3

Author(s):

Vladimir A Stepchenko ◽

Anatoly I Miroshnikov ◽

Frank Seela ◽

Igor A Mikhailopulo

Keyword(s):

Purine Nucleoside Phosphorylase ◽

Reaction Conditions ◽

E Coli ◽

No Formation ◽

Structural Peculiarities ◽

Substrate Properties ◽

Nucleoside Phosphorylases ◽

Derivatives Of

The trans-2-deoxyribosylation of 4-thiouracil (4SUra) and 2-thiouracil (2SUra), as well as 6-azauracil, 6-azathymine and 6-aza-2-thiothymine was studied using dG and E. coli purine nucleoside phosphorylase (PNP) for the in situ generation of 2-deoxy-α-D-ribofuranose-1-phosphate (dRib-1P) followed by its coupling with the bases catalyzed by either E. coli thymidine (TP) or uridine (UP) phosphorylases. 4SUra revealed satisfactory substrate activity for UP and, unexpectedly, complete inertness for TP; no formation of 2’-deoxy-2-thiouridine (2SUd) was observed under analogous reaction conditions in the presence of UP and TP. On the contrary, 2SU, 2SUd, 4STd and 2STd are good substrates for both UP and TP; moreover, 2SU, 4STd and 2’-deoxy-5-azacytidine (Decitabine) are substrates for PNP and the phosphorolysis of the latter is reversible. Condensation of 2SUra and 5-azacytosine with dRib-1P (Ba salt) catalyzed by the accordant UP and PNP in Tris∙HCl buffer gave 2SUd and 2’-deoxy-5-azacytidine in 27% and 15% yields, respectively. 6-Azauracil and 6-azathymine showed good substrate properties for both TP and UP, whereas only TP recognizes 2-thio-6-azathymine as a substrate. 5-Phenyl and 5-tert-butyl derivatives of 6-azauracil and its 2-thioxo derivative were tested as substrates for UP and TP, and only 5-phenyl- and 5-tert-butyl-6-azauracils displayed very low substrate activity. The role of structural peculiarities and electronic properties in the substrate recognition by E. coli nucleoside phosphorylases is discussed.

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Role of the molecular weight and the composition on the hydrolysis kinetics of monolayers of poly(α-hydroxy acid)s

Colloid & Polymer Science ◽

10.1007/s003960050444 ◽

1999 ◽

Vol 277 (8) ◽

pp. 709-718 ◽

Cited By ~ 11

Author(s):

Tz. Ivanova ◽

N. Grozev ◽

I. Panaiotov ◽

J. E. Proust

Keyword(s):

Molecular Weight ◽

Hydroxy Acid ◽

Hydrolysis Kinetics ◽

Kinetics Of

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Bioenergy II: Bio-Ethanol from Municipal Solid Waste (MSW): The Role of Biomass Properties and Structures During the Ethanol Conversion Process

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1918 ◽

2010 ◽

Vol 8 (1) ◽

Cited By ~ 2

Author(s):

Aiduan Li ◽

Majeda Khraisheh

Keyword(s):

Municipal Solid Waste ◽

Solid Waste ◽

Organic Waste ◽

Conversion Process ◽

Process Conditions ◽

Cellulose Content ◽

Substrate Composition ◽

Substrate Properties ◽

Promising Source

The emerging biofuel industry demands large amount of biomass feedstock. Although commercial ethanol has been produced from primary biomass sources such as corns, the global food crisis caused by the use of primary biomass has been raised. Thus, lignocellulosic biomass, known as second generation of biomass, has become a promising source for ethanol production. However, the more complex structure requires more advance technology. MSW with more than 60% of biodegradable composition, as one of the promising biomass sources has the potential benefits of replacing primary biomass and preventing environment from MSW pollution.In this paper, three major biodegradable municipal solid waste (BMSW) components: kitchen organic waste (KOW), green organic waste (GOW) and paper and card waste (PCW), are classified and characterised according to substrate composition, cellulose crystallinity, bulk density and particle size. The substrate composition indicates how much cellulose, lignin, hermicellulose each model waste has. The cellulose content shows the potential glucose/ethanol product yield. Other chemical composition such as lignin and hemicellulose indicates how easy of each model waste can be converted. These contents are also important information when selecting pretreatment methods and conversion process conditions in the following steps.Based on the comprehensive understanding of biomass structures and compositions, studies look into the effects of substrate properties (such crystallinity, presence of lignin and cellulose content on process performances during enzymatic hydrolysis adsorption. Results indicated how the adsorption process is affected by the substrate properties. This provides understanding of the role of substrate properties during enzyme-cellulose adsorption.

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Importance of Defluviitalea raffinosedens for Hydrolytic Biomass Degradation in Co-Culture with Hungateiclostridium thermocellum

Microorganisms ◽

10.3390/microorganisms8060915 ◽

2020 ◽

Vol 8 (6) ◽

pp. 915

Author(s):

Regina Rettenmaier ◽

Martina Schneider ◽

Bernhard Munk ◽

Michael Lebuhn ◽

Sebastian Jünemann ◽

...

Keyword(s):

Plant Biomass ◽

Cellulose Hydrolysis ◽

Taxonomic Composition ◽

Process Conditions ◽

Cellulose Breakdown ◽

Metabolic Properties ◽

Reactor Operating ◽

First Time ◽

Hydrolysis Of

Bacterial hydrolysis of polysaccharides is an important step for the production of sustainable energy, for example during the conversion of plant biomass to methane-rich biogas. Previously, Hungateiclostridium thermocellum was identified as cellulolytic key player in thermophilic biogas microbiomes with a great frequency as an accompanying organism. The aim of this study was to physiologically characterize a recently isolated co-culture of H. thermocellum and the saccharolytic bacterium Defluviitalea raffinosedens from a laboratory-scale biogas fermenter. The characterization focused on cellulose breakdown by applying the measurement of cellulose hydrolysis, production of metabolites, and the activity of secreted enzymes. Substrate degradation and the production of volatile metabolites was considerably enhanced when both organisms acted synergistically. The metabolic properties of H. thermocellum have been studied well in the past. To predict the role of D. raffinosedens in this bacterial duet, the genome of D. raffinosedens was sequenced for the first time. Concomitantly, to deduce the prevalence of D. raffinosedens in anaerobic digestion, taxonomic composition and transcriptional activity of different biogas microbiomes were analyzed in detail. Defluviitalea was abundant and metabolically active in reactor operating at highly efficient process conditions, supporting the importance of this organism for the hydrolysis of the raw substrate.

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Lattice induced crystallization of nanodroplets: the role of finite-size effects and substrate properties in controlling polymorphism

Nanoscale ◽

10.1039/c7nr08705e ◽

2018 ◽

Vol 10 (10) ◽

pp. 4921-4926 ◽

Cited By ~ 5

Author(s):

Julien Lam ◽

James F. Lutsko

Keyword(s):

Molecular Dynamics ◽

Size Effects ◽

Finite Size ◽

Solid Substrate ◽

General Phenomenon ◽

Finite Size Effects ◽

Substrate Properties ◽

Dynamics Simulations ◽

Induced Crystallization

Freezing a nanodroplet deposited on a solid substrate leads to the formation of crystalline structures. We study the inherent mechanisms underlying this general phenomenon by means of molecular dynamics simulations.

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Analysis of the Long Time Behavior of Enzymatic Cellulose Hydrolysis Kinetics

[Set Bioenergy, vol. 1+2] ◽

10.1515/energyo.0033.00104 ◽

2019 ◽

Author(s):

S Ramakrishnan ◽

G Brodeur ◽

J. C Telotte

Keyword(s):

Cellulose Hydrolysis ◽

Time Behavior ◽

Long Time Behavior ◽

Hydrolysis Kinetics ◽

Long Time

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A Comprehensive Study about the Role of Crosslink Density on the Tribological Behavior of DLC Coated Rubber

Materials ◽

10.3390/ma13235460 ◽

2020 ◽

Vol 13 (23) ◽

pp. 5460

Author(s):

Suleyman Bayrak ◽

Dominik Paulkowski ◽

Klaus Werner Stöckelhuber ◽

Benjamin Staar ◽

Bernd Mayer

Keyword(s):

Crosslink Density ◽

Wear Behavior ◽

Substrate Material ◽

Butadiene Rubber ◽

Friction Behavior ◽

Functional Layer ◽

Wear And Friction ◽

Substrate Properties ◽

The Impact

The friction and wear behavior of coated rubber components is strongly dependent on the substrate properties. This work deals with the impact of the crosslink density, i.e., the hardness of the rubber substrate on the tribological performance of uncoated and coated rubber. The hardness of nitrile butadiene rubber (NBR) is varied altering the sulfur content. Both the uncoated and coated rubber samples are characterized in terms of surface and mechanical properties. Tribological tests comprise the examination of the macroscopic contact area and the temperature in the contact zone. It was found that the functional layer enhances the wear resistance significantly. Apparently, the wear and friction behavior of the coated rubber correlates with the hardness and the bulk properties of the substrate material.

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