Download or read book Modeling and Analysis of Cellulose Hydrolysis by Thermobifida Fusca CEL5A CEL6B and CEL9A and Binary Mixtures of These Cellulases written by Tina Jeoh and published by . This book was released on 2004 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Micro Total Analysis Systems 2001 written by J. Michael Ramsey and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 722 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fifth International Conference on Micro Total Analysis Systems, also known as JlTAS 2001, will highlight the latest exciting events in the world ofminiaturized devices and systems for performing chemical and biochemical experimentation This conference has become mandatory for those of us working in this field as it is indeed helping to define our discipline. We are grateful to the people of the MESA Research Institute of the University of Twente, particularly Piet Bergveld and Albert van den Berg, for starting this meeting in 1994. Their original intention was for the JlTAS meeting to be a small informal workshop. This workshop flavor was sustained through the second meeting held in Basel in 1996, but already in 1998 at the third meeting in Banff it was clear that the "workshop" had become a conference with 420 attendees. It was due to this clearly growing interest in microchemical systems that it was decided we should consider gradually moving toward an annual format and prepare for the possibility that the meeting would increase in popularity. Albert van den Berg was still yearning for a workshop at the JlTAS 2000 meeting and planned a single session format. Again there was a large increase in submitted abstracts (more than 230 total) and a further increase in attendance. The JlTAS steering committee again agreed that we would have to prepare to address the demand the meeting was receiving.
Download or read book Studies of Thermobifida Fusca Cellulases Cel9A and Cel48A Using a Novel Kinetic Modeling Approach for the Enzymatic Digestion of Cellulose written by Maxim Kostylev and published by . This book was released on 2013 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lignocellulosic biomass is a potential source of sustainable transportation fuels, but efficient enzymatic saccharification of cellulose is a key challenge in its utilization. Enzymatic digestion of cellulose is a complex, heterogeneous process. An enzyme must repeatedly take multiple steps to hydrolyze the substrate to product. In addition, most bulk cellulose contains crystalline, semi-crystalline, and amorphous fractions, whose ratio likely changes during digestion. Access to substrate, rather than hydrolysis, is widely accepted to be the rate limiting step, as we showed experimentally using Cel9A, and the rate of digestion rapidly and continuously drops off as digestion proceeds. Predictive kinetic models typically incorporate different parameters and constants to account for the possible factors responsible for such behavior. Cellulose hydrolysis by individual cellulases and their mixtures can be modeled with a simple two-parameter model based on a modified classical kinetics scheme. Analogous to a fractal kinetics approach, the specific activity constant is replaced with a time-dependent activity coefficient in order to account for the continuous decrease in the digestion rate. The parameter that quantifies the time dependence of the digestion rate is an intrinsic constant for a given cellulase or mixture on a given substrate. The developed kinetic model was utilized in studies aimed to understand the function of aromatic residues located near the active site tunnel entrance of Cel48A and to develop a distinct model of synergistic cooperation between Cel48A and Cel9A. Additional experiments were carried out to establish experimentally the catalytic base in family 48 glycoside hydrolases.
Download or read book Alkaline Treatment of Alfalfa for Increasing Hydrolysis by Thermobifida Fusca to Fermentable Sugars written by Kate Elizabeth Brink O'Connor and published by . This book was released on 2006 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigating the Enzymatic Hydrolysis of Crystalline Cellulose Using Fluorescence Based Assays written by Navaneetha Santhanam and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydrolysis kinetics of bacterial microcrystalline cellulose (BMCC) by the cellulases of Thermobifida fusca was studied using fluorescence based assays in three ways. First, the binding of fluorescence-labeled Cel5A, Cel6B and Cel9A in ternary synergistic mixtures was assessed. A rapid high-throughput binding assay using microwell plates was developed to measure the bound fractions of the three cellulases at varying mole ratios of Cel6B and Cel9A, with Cel5A fixed at 10% of the total cellulase loading. This study revealed that the bound fractions of cellulases in ternary mixtures were additive, unlike the hydrolytic activity which was synergistic. Second, an experimental system was developed for the application of high resolution fluorescence microscopy to examine the binding of individual Cel5A, Cel6B and Cel9A to immobilized cellulose with varying morphologies. The immobilization technique allowed deposition of cellulose morphologies ranging from nanoscale cellulose fibers, to microscale cellulose fibril mats to sub-millimeter scale cellulose particles. Fluorescently labeled Cel5A, Cel6B and Cel9A were successfully integrated with fluorescently labeled cellulose to obtain a miniaturized reaction system which retained the intrinsic binding and hydrolytic capabilities of cellulases. Direct visualization of the binding behavior of individual cellulases on cellulose with different morphologies was achieved using this system which showed that the binding behavior depended strongly on the morphology and complexity of cellulose aggregates. Third, the significance of product inhibition by cellobiose as a rateretarding factor in the hydrolysis of BMCC by Cel9A and Cel9A-68, its construct lacking the family 2 cellulose binding module, was investigated. Fluorescently labeled BMCC was used as the substrate for an analysis of initial rates in the presence of exogenous cellobiose. Increasing cellobiose concentrations ranging from 1- 5mM were found to decrease the initial rate by 10 - 30% but increasing cellobiose concentrations from 5 to 60 mM did not cause a further decline in initial rates, clearly ruling out classical competitive inhibition as a possible mechanism. No definitive correlation was observed between binding and cellobiose concentrations for both enzymes indicating that the presence of cellobiose does not lead to significant enhancement or inhibition of binding.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2004 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanistic Studies of Thermobifida Fusca Exocellulase Cel6B written by Thu Van Vuong and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the mechanism by which cellulases catalyze cellulose hydrolysis can greatly contribute to the development of biofuels. The thermophilic bacterium Thermobifida fusca, a major degrader of plant cell walls in certain environments, secretes seven different cellulases including exocellulase Cel6B. This cellulase acts by an inverting mechanism; however, its catalytic acid and base residues had not been identified. Biochemical approaches confirmed D274 to be the catalytic acid residue. A single catalytic base residue could not be determined, as sodium azide assays showed no activity rescue for any single mutations of candidate residues. However, a double mutation of D226A and S232A knocked out enzymatic activity and its activity was partially rescued by sodium azide. We therefore propose a novel hydrolysis mechanism for T. fusca Cel6B involving a proton-transferring network to carry out the catalytic base function. T. fusca exocellulase Cel6B was also engineered to gain knowledge on the relationship between processivity and synergism as these properties are important for hydrolyzing crystalline cellulose. Mutations of several residues in the active site tunnel of Cel6B gave higher processivity. This improvement was confirmed by two assays: the ratio of soluble/insoluble reducing sugars as well as the ratio of oligosaccharide products. Surprisingly, the mutant enzyme, which has the highest processivity, showed the least synergism in mixtures with endocellulases, suggesting that improving exocellulase processivity might not always be an effective strategy for producing improved cellulase mixtures for biomass conversion. The highly processive Cel6B mutant enzymes were successfully fluorescently labeled, so these species can be used to visualize binding and track their movement on cellulose. The catalytic domains of Cel6B was found to bind non-productively to other polysaccharides; therefore, the balance between specific binding and non-specific adsorption should be always considered when engineering cellulases for hydrolyzing complex substrates. Using immuno-precipitation, Cel6B was demonstrated to contribute greatly to the hydrolysis of crystalline cellulose by T. fusca.
Download or read book Mechanism of Cellulose Hydrolysis and Substrate Binding by Thermobifida Fusca Cellulases written by Yongchao Li and published by . This book was released on 2008 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Level Investigations and Mathematical Modeling of Cellulase catalyzed Hydrolysis of Cellulose written by Jerome M. Fox and published by . This book was released on 2012 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cellulose-to-glucose conversion costs comprise one of the largest expenses in the production of lignocellulosic biofuels, a renewable alternative to traditional fossil fuels. Efforts to reduce these costs by improving the activity of cellulase enzymes, which act within multi-enzyme mixtures to catalyze the hydrolysis of cellulose, have been hindered by uncertainty surrounding the mechanistic origins of rate-limiting phenomena and by an incomplete understanding of complementary enzyme function. In this work, we employed mechanistic models of enzymatic action alongside experimental studies of enzyme-enzyme synergy to investigate kinetic impediments encountered by cellulase enzymes as they catalyze the hydrolysis of cellulose. Using several mechanistic models of enzymatic hydrolysis, we show how hydrolysis kinetics and optimal cellulolytic mixture compositions are dependent on the nature of the cellulosic substrate (i.e., particle shape, surface area, degree of polymerization) and the conditions under which it is depolymerized (i.e., hydrolysis and fermentation process conditions). By developing a method to estimate catalysis-specific products within multi-enzyme reactions, we show that cellobiohydrolase enzymes, which catalyze processive hydrolysis from cellulose chain ends, encounter rate limitations that result, not from intrinsic kinetics, but from slow rates of chain complexation and from morphological obstacles to processivity. And using photoactivated localization microscopy (PALM) to produce pointillistic maps of carbohydrate-binding modules (CBMs) bound to cotton, we develop an order parameter to quantify the different spatial arrangements of adsorbed CBMs and use that order parameter to explain synergy between cellulase enzymes designed to target different surface structures. The results of this work reveal strategies for using morphological targeting to enhance enzyme-enzyme cooperativity within cellulolytic mixtures, thereby improving their overall activity and lowering the cost of cellulose hydrolysis.
Download or read book Specificity of Proteolysis written by Borivoj Keil and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 343 pages. Available in PDF, EPUB and Kindle. Book excerpt: Specificity of Proteolysis presents a survey and conclusions on the action or proteinases - enzymes which are cleaving proteins or peptides. The specificity of proteinases which is determined as the sequence of amino acids at the cleavage site of a substrate, is an important criteria to choose an enzyme as tool in protein research. Whenever one is looking for an enzyme to act at a defined site or to give defined cleavage products one will find comprehensive information in this work. Comprehensive information about more than 280 endopeptidases which are based on the database LYSIS including a calculation program to determine cleavage sites, is given in the book.
Download or read book Biofuels written by Jonathan R. Mielenz and published by Humana Press. This book was released on 2012-03-07 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: This editor believes the public finally understands that bioenergy should be a critical new 39 component of our world’s future energy supply. While this new enlightenment might have 40 come from bioenergy’s environmentally friendly attributes and its renewable and sustain- 41 able nature, the reality is that the primary driver has been both the high cost of energy, 42 led recently by petroleum products, and the unique climatic changes such as local weather 43 events and reports of melting of ancient glaciers. I believe that much of the public under- 44 stands the primary cause of these changes is the growing demand for fossil fuels for heat- 45 ing and transportation needs driven by both population increases and dramatic economic 46 development around the globe. This increased demand, as well as global politics, has 47 impacted the costs for these energy products. At the same time, increased use of fossil fuels 48 has been liberating unprecedented levels of CO and other greenhouse gasses (GHGs) 49 2 that must be impacting the global climate. As a result, the world is looking for alternative 50 solutions. Renewable energy is one of the leading options as long as it is pursued in a sus- 51 tainable fashion. Of course, renewable energy has numerous sources, including wind, solar, 52 geothermal, ocean currents/tides, and bio-based energy. The latter category of renewable 53 energy is centered primarily on use of green plant matter, i. e.
Download or read book Aqueous Pretreatment of Plant Biomass for Biological and Chemical Conversion to Fuels and Chemicals written by Charles E. Wyman and published by John Wiley & Sons. This book was released on 2013-03-27 with total page 597 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plant biomass is attracting increasing attention as a sustainable resource for large-scale production of renewable fuels and chemicals. However, in order to successfully compete with petroleum, it is vital that biomass conversion processes are designed to minimize costs and maximize yields. Advances in pretreatment technology are critical in order to develop high-yielding, cost-competitive routes to renewable fuels and chemicals. Aqueous Pretreatment of Plant Biomass for Biological and Chemical Conversion to Fuels and Chemicals presents a comprehensive overview of the currently available aqueous pretreatment technologies for cellulosic biomass, highlighting the fundamental chemistry and biology of each method, key attributes and limitations, and opportunities for future advances. Topics covered include: • The importance of biomass conversion to fuels • The role of pretreatment in biological and chemical conversion of biomass • Composition and structure of biomass, and recalcitrance to conversion • Fundamentals of biomass pretreatment at low, neutral and high pH • Ionic liquid and organosolv pretreatments to fractionate biomass • Comparative data for application of leading pretreatments and effect of enzyme formulations • Physical and chemical features of pretreated biomass • Economics of pretreatment for biological processing • Methods of analysis and enzymatic conversion of biomass streams • Experimental pretreatment systems from multiwell plates to pilot plant operations This comprehensive reference book provides an authoritative source of information on the pretreatment of cellulosic biomass to aid those experienced in the field to access the most current information on the topic. It will also be invaluable to those entering the growing field of biomass conversion.
Download or read book Biomass as a Sustainable Energy Source for the Future written by Wiebren de Jong and published by John Wiley & Sons. This book was released on 2014-11-03 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focusing on the conversion of biomass into gas or liquid fuels the book covers physical pre-treatment technologies, thermal, chemical and biochemical conversion technologies • Details the latest biomass characterization techniques • Explains the biochemical and thermochemical conversion processes • Discusses the development of integrated biorefineries, which are similar to petroleum refineries in concept, covering such topics as reactor configurations and downstream processing • Describes how to mitigate the environmental risks when using biomass as fuel • Includes many problems, small projects, sample calculations and industrial application examples
Download or read book Encyclopedia of Food Science written by Johann Wells and published by . This book was released on 2015-01-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides all the basic and advanced concepts of fruit science. It includes different aspects of food science, such as medical problems associated with the food consumption of some specific types. With the ever growing need of food in order to satisfy the population, food scientists and specialists have compiled their knowledge of food science in this book.
Download or read book Recent Progress in Bioconversion of Lignocellulosics written by George T. Tsao and published by Springer Science & Business Media. This book was released on 1999-09-02 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reports the latest advances in the science and technology related to the conversion of lignocellulosics. A portion of the volume is devoted to molecular biology of the enzymes and the microbes involved in the conversion. Hydrolysis of cellulose continues to be of prime importance in the overall conversion scheme. Reaction kinetics and mechanisms of cellulases as well as the state-of-the-art methods of cellulase production by submerged fermentation and also by solid state fermentation are included in the volume. The latest advances made in dilute acid hydrolysis of cellulose are described. Finally, some exciting methods and perspectives for bioconverion of lignocellulosics into ethanol, organic acids and other value-added products are described. This volume should be useful to researchers in this area. It should also be helpful to those who want a concise overview of lignocellulosics.
Download or read book Plant Cell Walls written by Nicholas C. Carpita and published by Springer. This book was released on 2012-12-06 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is a comprehensive collection of articles that cover aspects of cell wall research in the genomic era. Some 2500 genes are involved in some way in wall biogenesis and turnover, from generation of substrates, to polysaccharide and lignin synthesis, assembly, and rearrangement in the wall. Although a great number of genes and gene families remain to be characterized, this issue provides a census of the genes that have been discovered so far. The articles comprising this issue not only illustrate the enormous progress made in identifying the wealth of wall-related genes but they also show the future directions and how far we have to go. As cell walls are an enormously important source of raw material, we anticipate that cell-wall-related genes are of significant economic importance. Examples include the modification of pectin-cross-linking or cell-cell adhesion to increase shelf life of fruits and vegetables, the enhancement of dietary fiber contents of cereals, the improvement of yield and quality of fibers, and the relative allocation of carbon to wall biomass for use as biofuels. The book is intended for academic and professional scientists working in the area of plant biology as well as material chemists and engineers, and food scientists who define new ways to use cell walls.
Download or read book Biomass Conversion written by Michael E. Himmel and published by Humana Press. This book was released on 2012-07-28 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biomass conversion research is a combination of basic science, applied science, and engineering testing and analysis. Conversion science includes the initial treatment (called pre-treatment) of the feedstock to render it more amenable to enzyme action, enzymatic saccharification, and finally product formation by microbiological or chemical processes. In Biomass Conversion: Methods and Protocols, expert researchers in the field detail methods which are now commonly used to study biomass conversion. These methods include Biomass Feedstocks and Cellulose, Plant Cell Wall Degrading Enzymes and Microorganisms, and Lignins and Hemicelluloses. Written in the highly successful Methods in Molecular BiologyTM series format, the chapters include the kind of detailed description and implementation advice that is crucial for getting informed, reproducible results in the laboratory.
