1
|
Al Talebi ZA, Al-Kawaz HS, Mahdi RK, Al-Hassnawi AT, Alta'ee AH, Hadwan AM, Khudhair DA, Hadwan MH. An optimized protocol for estimating cellulase activity in biological samples. Anal Biochem 2022; 655:114860. [PMID: 35985481 DOI: 10.1016/j.ab.2022.114860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 11/01/2022]
Abstract
Cellulase is a microbial enzyme responsible for degrading the β-1,4 glycoside bond in polysaccharide cellulose, which is abundant in various animal foodstuffs. Cellulase is an important industrial enzyme used for various purposes, including biopolishing textile fibers, softening garments, biostoning denim fabric, and removing excess color from textiles. In the food industry, cellulase is combined with pectinase and hemicellulase. Therefore, the need for a reliable, fast, and inexpensive cellulase activity protocol that could be used with diverse biological and environmental samples is great. This study developed a novel method to quantify cellulase activity using picric acid (PCA), which reacts with generated glucose molecules to produce mahogany red picramic acid. This PCA-cellulase method uses sodium hydroxide instead of sodium carbonate to provide alkalinity in the reaction solution, increasing the stability of picramic acid and the sensitivity and linearity of the reaction. It also overcomes the limitations of previous methods. It is notable for its dependence on few chemicals with low concentrations compared to previous methods that depend on many chemicals with high concentrations. The PCA-cellulase method was optimized using the Box-Behnken design, and its accuracy was determined using a response surface approach. A Bland-Altman cellulase activity graph was used to validate the PCA-cellulase method with a correlation coefficient of 0.9991. Therefore, the novel PCA-cellulase method provides accurate results that are comparable to existing methods.
Collapse
Affiliation(s)
- Zainab Abbas Al Talebi
- Chemistry Dept., College of Science, University of Babylon, Hilla City, Babylon Governorate, p.o. 51002, Iraq.
| | - Hawraa Saad Al-Kawaz
- Department of Medical Laboratories Techniques, Al-Mustaqbal University College, Babylon, Iraq.
| | | | | | | | - Asad M Hadwan
- Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran.
| | - Dunia Abbas Khudhair
- Department of Medical Laboratories Techniques, Al-Mustaqbal University College, Babylon, Iraq.
| | - Mahmoud Hussein Hadwan
- Chemistry Dept., College of Science, University of Babylon, Hilla City, Babylon Governorate, p.o. 51002, Iraq.
| |
Collapse
|
2
|
Lin HY, Chen X, Dong J, Yang JF, Xiao H, Ye Y, Li LH, Zhan CG, Yang WC, Yang GF. Rational Redesign of Enzyme via the Combination of Quantum Mechanics/Molecular Mechanics, Molecular Dynamics, and Structural Biology Study. J Am Chem Soc 2021; 143:15674-15687. [PMID: 34542283 DOI: 10.1021/jacs.1c06227] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Increasing demands for efficient and versatile chemical reactions have prompted innovations in enzyme engineering. A major challenge in engineering α-ketoglutarate-dependent oxygenases is to develop a rational strategy which can be widely used for directly evolving the desired mutant to generate new products. Herein, we report a strategy for rational redesign of a model enzyme, 4-hydroxyphenylpyruvate dioxygenase (HPPD), based on quantum mechanics/molecular mechanics (QM/MM) calculation and molecular dynamic simulations. This strategy enriched our understanding of the HPPD catalytic reaction pathway and led to the discovery of a series of HPPD mutants producing hydroxyphenylacetate (HPA) as the alternative product other than the native product homogentisate. The predicted HPPD-Fe(IV)═O-HPA intermediate was further confirmed by the crystal structure of Arabidopsis thaliana HPPD/S267W complexed with HPA. These findings not only provide a good understanding of the structure-function relationship of HPPD but also demonstrate a generally applicable platform for the development of biocatalysts.
Collapse
Affiliation(s)
- Hong-Yan Lin
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health, College of Chemistry, Central China Normal University, Wuhan 430079, P.R. China
| | - Xi Chen
- College of Chemistry and Material Science, South-Central University for Nationalities, Wuhan 430074, P.R. China
| | - Jin Dong
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health, College of Chemistry, Central China Normal University, Wuhan 430079, P.R. China
| | - Jing-Fang Yang
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health, College of Chemistry, Central China Normal University, Wuhan 430079, P.R. China
| | - Han Xiao
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health, College of Chemistry, Central China Normal University, Wuhan 430079, P.R. China
| | - Ying Ye
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health, College of Chemistry, Central China Normal University, Wuhan 430079, P.R. China
| | - Lin-Hui Li
- College of Chemistry and Material Science, South-Central University for Nationalities, Wuhan 430074, P.R. China
| | - Chang-Guo Zhan
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536, United States
| | - Wen-Chao Yang
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health, College of Chemistry, Central China Normal University, Wuhan 430079, P.R. China
| | - Guang-Fu Yang
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health, College of Chemistry, Central China Normal University, Wuhan 430079, P.R. China
| |
Collapse
|
3
|
Wang Y, Wang G, Moitessier N, Mittermaier AK. Enzyme Kinetics by Isothermal Titration Calorimetry: Allostery, Inhibition, and Dynamics. Front Mol Biosci 2020; 7:583826. [PMID: 33195429 PMCID: PMC7604385 DOI: 10.3389/fmolb.2020.583826] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/11/2020] [Indexed: 12/14/2022] Open
Abstract
Isothermal titration calorimetry (ITC) involves accurately measuring the heat that is released or absorbed in real time when one solution is titrated into another. This technique is usually used to measure the thermodynamics of binding reactions. However, there is mounting interest in using it to measure reaction kinetics, particularly enzymatic catalysis. This application of ITC has been steadily growing for the past two decades, and the method is proving to be sensitive, generally applicable, and capable of providing information on enzyme activity that is difficult to obtain using traditional biochemical assays. This review aims to give a broad overview of the use of ITC to measure enzyme kinetics. It describes several different classes of ITC experiment, their strengths and weaknesses, and recent methodological advancements. A summary of applications in the literature is given and several examples where ITC has been used to investigate challenging aspects of enzyme behavior are presented in more detail. These include examples of allostery, where small-molecule binding outside the active site modulates activity. We describe the use of ITC to measure the strength, mode (i.e., competitive, uncompetitive, or mixed), and association and dissociation kinetics of enzyme inhibitors. Further, we provide examples of ITC applied to complex, heterogeneous mixtures, such as insoluble substrates and live cells. These studies exemplify the wide range of problems where ITC can provide answers, and illustrate the versatility of the technique and potential for future development and applications.
Collapse
Affiliation(s)
- Yun Wang
- Department of Chemistry, McGill University, Montreal, QC, Canada
| | - Guanyu Wang
- Department of Chemistry, McGill University, Montreal, QC, Canada
| | | | | |
Collapse
|
4
|
Phytase catalysis of dephosphorylation studied using isothermal titration calorimetry and electrospray ionization time-of-flight mass spectroscopy. Anal Biochem 2020; 606:113859. [DOI: 10.1016/j.ab.2020.113859] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/29/2020] [Accepted: 07/01/2020] [Indexed: 11/21/2022]
|
5
|
Di Trani JM, Moitessier N, Mittermaier AK. Complete Kinetic Characterization of Enzyme Inhibition in a Single Isothermal Titration Calorimetric Experiment. Anal Chem 2018; 90:8430-8435. [DOI: 10.1021/acs.analchem.8b00993] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
|
6
|
Frasca V. Using Isothermal Titration Calorimetry Techniques to Quantify Enzyme Kinetics. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1089/ind.2016.29040.vfr] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
7
|
Cellulases: Classification, Methods of Determination and Industrial Applications. Appl Biochem Biotechnol 2016; 179:1346-80. [PMID: 27068832 DOI: 10.1007/s12010-016-2070-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 03/31/2016] [Indexed: 10/22/2022]
Abstract
Microbial cellulases have been receiving worldwide attention, as they have enormous potential to process the most abundant cellulosic biomass on this planet and transform it into sustainable biofuels and other value added products. The synergistic action of endoglucanases, exoglucanases, and β-glucosidases is required for the depolymerization of cellulose to fermentable sugars for transformation in to useful products using suitable microorganisms. The lack of a better understanding of the mechanisms of individual cellulases and their synergistic actions is the major hurdles yet to be overcome for large-scale commercial applications of cellulases. We have reviewed various microbial cellulases with a focus on their classification with mechanistic aspects of cellulase hydrolytic action, insights into novel approaches for determining cellulase activity, and potential industrial applications of cellulases.
Collapse
|
8
|
Maximova K, Trylska J. Kinetics of trypsin-catalyzed hydrolysis determined by isothermal titration calorimetry. Anal Biochem 2015; 486:24-34. [DOI: 10.1016/j.ab.2015.06.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 06/13/2015] [Accepted: 06/16/2015] [Indexed: 10/23/2022]
|
9
|
Guerriero G, Hausman JF, Strauss J, Ertan H, Siddiqui KS. Destructuring plant biomass: focus on fungal and extremophilic cell wall hydrolases. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2015; 234:180-93. [PMID: 25804821 PMCID: PMC4937988 DOI: 10.1016/j.plantsci.2015.02.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 02/17/2015] [Accepted: 02/18/2015] [Indexed: 05/05/2023]
Abstract
The use of plant biomass as feedstock for biomaterial and biofuel production is relevant in the current bio-based economy scenario of valorizing renewable resources. Fungi, which degrade complex and recalcitrant plant polymers, secrete different enzymes that hydrolyze plant cell wall polysaccharides. The present review discusses the current research trends on fungal, as well as extremophilic cell wall hydrolases that can withstand extreme physico-chemical conditions required in efficient industrial processes. Secretomes of fungi from the phyla Ascomycota, Basidiomycota, Zygomycota and Neocallimastigomycota are presented along with metabolic cues (nutrient sensing, coordination of carbon and nitrogen metabolism) affecting their composition. We conclude the review by suggesting further research avenues focused on the one hand on a comprehensive analysis of the physiology and epigenetics underlying cell wall degrading enzyme production in fungi and on the other hand on the analysis of proteins with unknown function and metagenomics of extremophilic consortia. The current advances in consolidated bioprocessing, altered secretory pathways and creation of designer plants are also examined. Furthermore, recent developments in enhancing the activity, stability and reusability of enzymes based on synergistic, proximity and entropic effects, fusion enzymes, structure-guided recombination between homologous enzymes and magnetic enzymes are considered with a view to improving saccharification.
Collapse
Affiliation(s)
- Gea Guerriero
- Environmental Research and Innovation (ERIN), Luxembourg Institute of Science and Technology (LIST), Esch/Alzette, Luxembourg.
| | - Jean-Francois Hausman
- Environmental Research and Innovation (ERIN), Luxembourg Institute of Science and Technology (LIST), Esch/Alzette, Luxembourg
| | - Joseph Strauss
- Department of Applied Genetics and Cell Biology, Fungal Genetics and Genomics Unit, University of Natural Resources and Life Sciences Vienna (BOKU), University and Research Center Campus Tulln-Technopol, Tulln/Donau, Austria; Health and Environment Department, Austrian Institute of Technology GmbH - AIT, University and Research Center Campus Tulln-Technopol, Tulln/Donau, Austria
| | - Haluk Ertan
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia; Department of Molecular Biology and Genetics, Istanbul University, Turkey
| | - Khawar Sohail Siddiqui
- Biology Department, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia.
| |
Collapse
|
10
|
Pellegrini VOA, Lei N, Kyasaram M, Olsen JP, Badino SF, Windahl MS, Colussi F, Cruys-Bagger N, Borch K, Westh P. Reversibility of substrate adsorption for the cellulases Cel7A, Cel6A, and Cel7B from Hypocrea jecorina. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12602-12609. [PMID: 25322452 DOI: 10.1021/la5024423] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Adsorption of cellulases on the cellulose surface is an integral part of the catalytic mechanism, and a detailed description of the adsorption process is therefore required for a fundamental understanding of this industrially important class of enzymes. However, the mode of adsorption has proven intricate, and several key questions remain open. Perhaps most notably it is not clear whether the adsorbed enzyme is in dynamic equilibrium with the free population or irreversibly associated with no or slow dissociation. To address this, we have systematically investigated adsorption reversibility for two cellobiohydrolases (Cel7A and Cel6A) and one endoglucanase (Cel7B) on four types of pure cellulose substrates. Specifically, we monitored dilution-induced release of adsorbed enzyme in samples that had previously been brought to a steady state (constant concentration of free enzyme). In simple dilution experiments (without centrifugation), the results consistently showed full reversibility. In contrast to this, resuspension of enzyme-substrate pellets separated by centrifugation showed extensive irreversibility. We conclude that these enzymes are in a dynamic equilibrium between free and adsorbed states but suggest that changes in the physical properties of cellulose caused by compaction of the pellet hampers subsequent release of adsorbed enzyme. This latter effect may be pertinent to both previous controversies in the literature on adsorption reversibility and the development of enzyme recycling protocols in the biomass industry.
Collapse
Affiliation(s)
- Vanessa O A Pellegrini
- Research Unit for Functional Biomaterials, NSM, Roskilde University , 1 Universitetsvej, Build. 18.1, DK-4000 Roskilde, Denmark
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Kari J, Olsen J, Borch K, Cruys-Bagger N, Jensen K, Westh P. Kinetics of cellobiohydrolase (Cel7A) variants with lowered substrate affinity. J Biol Chem 2014; 289:32459-68. [PMID: 25271162 DOI: 10.1074/jbc.m114.604264] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cellobiohydrolases are exo-active glycosyl hydrolases that processively convert cellulose to soluble sugars, typically cellobiose. They effectively break down crystalline cellulose and make up a major component in industrial enzyme mixtures used for deconstruction of lignocellulosic biomass. Identification of the rate-limiting step for cellobiohydrolases remains controversial, and recent reports have alternately suggested either association (on-rate) or dissociation (off-rate) as the overall bottleneck. Obviously, this uncertainty hampers both fundamental mechanistic understanding and rational design of enzymes with improved industrial applicability. To elucidate the role of on- and off-rates, respectively, on the overall kinetics, we have expressed a variant in which a tryptophan residue (Trp-38) in the middle of the active tunnel has been replaced with an alanine. This mutation weakens complex formation, and the population of substrate-bound W38A was only about half of the wild type. Nevertheless, the maximal, steady-state rate was twice as high for the variant enzyme. It is argued that these opposite effects on binding and activity can be reconciled if the rate-limiting step is after the catalysis (i.e. in the dissociation process).
Collapse
Affiliation(s)
- Jeppe Kari
- From Department of Science, Systems and Models, Research Unit for Functional Biomaterials, Roskilde University, 1 Universitetsvej, DK-4000 Roskilde, Denmark and
| | - Johan Olsen
- From Department of Science, Systems and Models, Research Unit for Functional Biomaterials, Roskilde University, 1 Universitetsvej, DK-4000 Roskilde, Denmark and
| | - Kim Borch
- Novozymes A/S, Krogshøjvej 36, Bagsværd DK-2880, Denmark
| | - Nicolaj Cruys-Bagger
- From Department of Science, Systems and Models, Research Unit for Functional Biomaterials, Roskilde University, 1 Universitetsvej, DK-4000 Roskilde, Denmark and
| | - Kenneth Jensen
- Novozymes A/S, Krogshøjvej 36, Bagsværd DK-2880, Denmark
| | - Peter Westh
- From Department of Science, Systems and Models, Research Unit for Functional Biomaterials, Roskilde University, 1 Universitetsvej, DK-4000 Roskilde, Denmark and
| |
Collapse
|
12
|
Alasepp K, Borch K, Cruys-Bagger N, Badino S, Jensen K, Sørensen TH, Windahl MS, Westh P. In situ stability of substrate-associated cellulases studied by DSC. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7134-7142. [PMID: 24856176 DOI: 10.1021/la500161e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This work shows that differential scanning calorimetry (DSC) can be used to monitor the stability of substrate-adsorbed cellulases during long-term hydrolysis of insoluble cellulose. Thermal transitions of adsorbed enzyme were measured regularly in subsets of a progressing hydrolysis, and the size of the transition peak was used as a gauge of the population of native enzyme. Analogous measurements were made for enzymes in pure buffer. Investigations of two cellobiohydrolases, Cel6A and Cel7A, from Trichoderma reesei, which is an anamorph of the fungus Hypocrea jerorina, showed that these enzymes were essentially stable at 25 °C. Thus, over a 53 h experiment, Cel6A lost less than 15% of the native population and Cel7A showed no detectable loss for either the free or substrate-adsorbed state. At higher temperatures we found significant losses in the native populations, and at the highest tested temperature (49 °C) about 80% Cel6A and 35% of Cel7A was lost after 53 h of hydrolysis. The data consistently showed that Cel7A was more long-term stable than Cel6A and that substrate-associated enzyme was less long-term stable than enzyme in pure buffer stored under otherwise equal conditions. There was no correlation between the intrinsic stability, specified by the transition temperature in the DSC, and the long-term stability derived from the peak area. The results are discussed with respect to the role of enzyme denaturation for the ubiquitous slowdown observed in the enzymatic hydrolysis of cellulose.
Collapse
Affiliation(s)
- Kadri Alasepp
- Research Unit for Functional Biomaterials, NSM, Roskilde University. 1 Universitetsvej , Build. 18.1, DK-4000 Roskilde Denmark
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Siddiqui KS, Ertan H, Charlton T, Poljak A, Daud Khaled A, Yang X, Marshall G, Cavicchioli R. Versatile peroxidase degradation of humic substances: Use of isothermal titration calorimetry to assess kinetics, and applications to industrial wastes. J Biotechnol 2014; 178:1-11. [DOI: 10.1016/j.jbiotec.2014.03.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/24/2014] [Accepted: 03/03/2014] [Indexed: 01/07/2023]
|
14
|
Cruys-Bagger N, Badino SF, Tokin R, Gontsarik M, Fathalinejad S, Jensen K, Toscano MD, Sørensen TH, Borch K, Tatsumi H, Väljamäe P, Westh P. A pyranose dehydrogenase-based biosensor for kinetic analysis of enzymatic hydrolysis of cellulose by cellulases. Enzyme Microb Technol 2014; 58-59:68-74. [DOI: 10.1016/j.enzmictec.2014.03.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 03/03/2014] [Accepted: 03/04/2014] [Indexed: 10/25/2022]
|
15
|
Cruys-Bagger N, Tatsumi H, Ren GR, Borch K, Westh P. Transient kinetics and rate-limiting steps for the processive cellobiohydrolase Cel7A: effects of substrate structure and carbohydrate binding domain. Biochemistry 2013; 52:8938-48. [PMID: 24228828 DOI: 10.1021/bi401210n] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cellobiohydrolases are exoacting, processive enzymes that effectively hydrolyze crystalline cellulose. They have attracted considerable interest because of their role in both natural carbon cycling and industrial enzyme cocktails used for the deconstruction of cellulosic biomass, but many mechanistic and regulatory aspects of their heterogeneous catalysis remain poorly understood. Here, we address this by applying a deterministic model to real-time kinetic data with high temporal resolution. We used two variants of the cellobiohydrolase Cel7A from Hypocrea jecorina , and three types of cellulose as substrate. Analysis of the pre-steady-state regime allowed delineation rate constants for both fast and slow steps in the enzymatic cycle and assessment of how these constants influenced the rate of hydrolysis at quasi-steady state. Processive movement on the cellulose strand advanced with characteristic times of 0.15-0.7 s per step at 25 °C, and the rate was highest on amorphous substrate. The cellulose binding module was found to raise this rate on crystalline, but not on amorphous, substrate. The rapid processive movement signified high intrinsic reactivity, but this parameter had marginal influence on the steady-state rate. This was because dissociation and association were slower and, hence, rate limiting. Specifically, the dissociation from the strand was found to occur with characteristic times of 45-100 s. This meant that dissociation was the bottleneck, except at very low substrate loads (0.5-1 g/L), where association became slower.
Collapse
Affiliation(s)
- Nicolaj Cruys-Bagger
- Research Unit for Functional Biomaterials, NSM, Roskilde University , Universitetsvej 1, DK-4000 Roskilde, Denmark
| | | | | | | | | |
Collapse
|
16
|
Teugjas H, Väljamäe P. Product inhibition of cellulases studied with 14C-labeled cellulose substrates. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:104. [PMID: 23883520 PMCID: PMC3726336 DOI: 10.1186/1754-6834-6-104] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 07/11/2013] [Indexed: 05/02/2023]
Abstract
BACKGROUND As a green alternative for the production of transportation fuels, the enzymatic hydrolysis of lignocellulose and subsequent fermentation to ethanol are being intensively researched. To be economically feasible, the hydrolysis of lignocellulose must be conducted at a high concentration of solids, which results in high concentrations of hydrolysis end-products, cellobiose and glucose, making the relief of product inhibition of cellulases a major challenge in the process. However, little quantitative information on the product inhibition of individual cellulases acting on cellulose substrates is available because it is experimentally difficult to assess the hydrolysis of the heterogeneous polymeric substrate in the high background of added products. RESULTS The cellobiose and glucose inhibition of thermostable cellulases from Acremonium thermophilum, Thermoascus aurantiacus, and Chaetomium thermophilum acting on uniformly 14C-labeled bacterial cellulose and its derivatives, 14C-bacterial microcrystalline cellulose and 14C-amorphous cellulose, was studied. Cellulases from Trichoderma reesei were used for comparison. The enzymes most sensitive to cellobiose inhibition were glycoside hydrolase (GH) family 7 cellobiohydrolases (CBHs), followed by family 6 CBHs and endoglucanases (EGs). The strength of glucose inhibition followed the same order. The product inhibition of all enzymes was relieved at higher temperatures. The inhibition strength measured for GH7 CBHs with low molecular-weight model substrates did not correlate with that measured with 14C-cellulose substrates. CONCLUSIONS GH7 CBHs are the primary targets for product inhibition of the synergistic hydrolysis of cellulose. The inhibition must be studied on cellulose substrates instead of on low molecular-weight model substrates when selecting enzymes for lignocellulose hydrolysis. The advantages of using higher temperatures are an increase in the catalytic efficiency of enzymes and the relief of product inhibition.
Collapse
Affiliation(s)
- Hele Teugjas
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23b – 202, Tartu 51010, Estonia
| | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23b – 202, Tartu 51010, Estonia
| |
Collapse
|
17
|
Murphy L, Bohlin C, Baumann MJ, Olsen SN, Sørensen TH, Anderson L, Borch K, Westh P. Product inhibition of five Hypocrea jecorina cellulases. Enzyme Microb Technol 2013; 52:163-9. [DOI: 10.1016/j.enzmictec.2013.01.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 01/02/2013] [Accepted: 01/03/2013] [Indexed: 10/27/2022]
|
18
|
Kinetic and thermodynamic characterization of the functional properties of a hybrid versatile peroxidase using isothermal titration calorimetry: Insight into manganese peroxidase activation and lignin peroxidase inhibition. Biochimie 2012; 94:1221-31. [PMID: 22586704 DOI: 10.1016/j.biochi.2012.02.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Isothermal titration calorimetry (ITC) was developed for measuring lignin peroxidase (LiP) and manganese peroxidase (MnP) activities of versatile peroxidase (VP) from Bjerkandera adusta. Developing an ITC approach provided an alternative to colorimetric methods that enabled reaction kinetics to be accurately determined. Although VP from Bjerkandera adjusta is a hybrid enzyme, specific conditions of [Mn+2] and pH were defined that limited activity to either LiP or MnP activities, or enabled both to be active simultaneously. MnP activity was found to be more efficient than LiP activity, with activity increasing with increasing concentrations of Mn+2. These properties of MnP were explained by a second metal binding site involved in homotropic substrate (Mn+2) activation. The activation of MnP was also accompanied by a decrease in both activation energy and substrate (Mn) affinity, reflecting a flexible enzyme structure. In contrast to MnP activity, LiP activity was inhibited by high dye (substrate) concentrations arising from uncompetitive substrate inhibition caused by substrate binding to a site distinct from the catalytic site. Our study provides a new level of understanding about the mechanism of substrate regulation of catalysis in VP from B. adjusta, providing insight into a class of enzyme, hybrid class II peroxidases, for which little experimental data is available.
Collapse
|
19
|
Cruys-Bagger N, Ren G, Tatsumi H, Baumann MJ, Spodsberg N, Andersen HD, Gorton L, Borch K, Westh P. An amperometric enzyme biosensor for real-time measurements of cellobiohydrolase activity on insoluble cellulose. Biotechnol Bioeng 2012; 109:3199-204. [PMID: 22767376 DOI: 10.1002/bit.24593] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 06/08/2012] [Accepted: 06/20/2012] [Indexed: 11/07/2022]
Abstract
An amperometric enzyme biosensor for continuous detection of cellobiose has been implemented as an enzyme assay for cellulases. We show that the initial kinetics for cellobiohydrolase I, Cel7A from Trichoderma reesei, acting on different types of cellulose substrates, semi-crystalline and amorphous, can be monitored directly and in real-time by an enzyme-modified electrode based on cellobiose dehydrogenase (CDH) from Phanerochaete chrysosporium (Pc). PcCDH was cross-linked and immobilized on the surface of a carbon paste electrode which contained a mediator, benzoquinone. An oxidation current of the reduced mediator, hydroquinone, produced by the CDH-catalyzed reaction with cellobiose, was recorded under constant-potential amperometry at +0.5 V (vs. Ag/AgCl). The CDH-biosensors showed high sensitivity (87.7 µA mM(-1) cm(-2)), low detection limit (25 nM), and fast response time (t(95%) ≈ 3 s) and this provided experimental access to the transient kinetics of cellobiohydrolases acting on insoluble cellulose. The response from the CDH-biosensor during enzymatic hydrolysis was corrected for the specificity of PcCDH for the β-anomer of cello-oligosaccharides and the approach were validated against HPLC. It is suggested that quantitative, real-time data on pure insoluble cellulose substrates will be useful in attempts to probe the molecular mechanism underlying enzymatic hydrolysis of cellulose.
Collapse
Affiliation(s)
- Nicolaj Cruys-Bagger
- Research Unit for Functional Biomaterials, NSM, Roskilde University, Universitetsvej 1, DK-4000 Roskilde, Denmark
| | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Ghai R, Falconer RJ, Collins BM. Applications of isothermal titration calorimetry in pure and applied research--survey of the literature from 2010. J Mol Recognit 2012; 25:32-52. [PMID: 22213449 DOI: 10.1002/jmr.1167] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Isothermal titration calorimetry (ITC) is a biophysical technique for measuring the formation and dissociation of molecular complexes and has become an invaluable tool in many branches of science from cell biology to food chemistry. By measuring the heat absorbed or released during bond formation, ITC provides accurate, rapid, and label-free measurement of the thermodynamics of molecular interactions. In this review, we survey the recent literature reporting the use of ITC and have highlighted a number of interesting studies that provide a flavour of the diverse systems to which ITC can be applied. These include measurements of protein-protein and protein-membrane interactions required for macromolecular assembly, analysis of enzyme kinetics, experimental validation of molecular dynamics simulations, and even in manufacturing applications such as food science. Some highlights include studies of the biological complex formed by Staphylococcus aureus enterotoxin C3 and the murine T-cell receptor, the mechanism of membrane association of the Parkinson's disease-associated protein α-synuclein, and the role of non-specific tannin-protein interactions in the quality of different beverages. Recent developments in automation are overcoming limitations on throughput imposed by previous manual procedures and promise to greatly extend usefulness of ITC in the future. We also attempt to impart some practical advice for getting the most out of ITC data for those researchers less familiar with the method.
Collapse
Affiliation(s)
- Rajesh Ghai
- Institute for Molecular Bioscience (IMB), University of Queensland, St. Lucia, Queensland, 4072, Australia
| | | | | |
Collapse
|
21
|
Cruys-Bagger N, Elmerdahl J, Praestgaard E, Tatsumi H, Spodsberg N, Borch K, Westh P. Pre-steady-state kinetics for hydrolysis of insoluble cellulose by cellobiohydrolase Cel7A. J Biol Chem 2012; 287:18451-8. [PMID: 22493488 DOI: 10.1074/jbc.m111.334946] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transient kinetic behavior of enzyme reactions prior to the establishment of steady state is a major source of mechanistic information, yet this approach has not been utilized for cellulases acting on their natural substrate, insoluble cellulose. Here, we elucidate the pre-steady-state regime for the exo-acting cellulase Cel7A using amperometric biosensors and an explicit model for processive hydrolysis of cellulose. This analysis allows the identification of a pseudo-steady-state period and quantification of a processivity number as well as rate constants for the formation of a threaded enzyme complex, processive hydrolysis, and dissociation, respectively. These kinetic parameters elucidate limiting factors in the cellulolytic process. We concluded, for example, that Cel7A cleaves about four glycosidic bonds/s during processive hydrolysis. However, the results suggest that stalling the processive movement and low off-rates result in a specific activity at pseudo-steady state that is 10-25-fold lower. It follows that the dissociation of the enzyme-substrate complex (half-time of ~30 s) is rate-limiting for the investigated system. We suggest that this approach can be useful in attempts to unveil fundamental reasons for the distinctive variability in hydrolytic activity found in different cellulase-substrate systems.
Collapse
Affiliation(s)
- Nicolaj Cruys-Bagger
- Department of Science, Systems, and Models, Roskilde University, Roskilde, Denmark
| | | | | | | | | | | | | |
Collapse
|
22
|
Murphy L, Cruys-Bagger N, Damgaard HD, Baumann MJ, Olsen SN, Borch K, Lassen SF, Sweeney M, Tatsumi H, Westh P. Origin of initial burst in activity for Trichoderma reesei endo-glucanases hydrolyzing insoluble cellulose. J Biol Chem 2012; 287:1252-60. [PMID: 22110134 PMCID: PMC3256860 DOI: 10.1074/jbc.m111.276485] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 11/10/2011] [Indexed: 11/06/2022] Open
Abstract
The kinetics of cellulose hydrolysis have long been described by an initial fast hydrolysis rate, tapering rapidly off, leading to a process that takes days rather than hours to complete. This behavior has been mainly attributed to the action of cellobiohydrolases and often linked to the processive mechanism of this exo-acting group of enzymes. The initial kinetics of endo-glucanases (EGs) is far less investigated, partly due to a limited availability of quantitative assay technologies. We have used isothermal calorimetry to monitor the early time course of the hydrolysis of insoluble cellulose by the three main EGs from Trichoderma reesei (Tr): TrCel7B (formerly EG I), TrCel5A (EG II), and TrCel12A (EG III). These endo-glucanases show a distinctive initial burst with a maximal rate that is about 5-fold higher than the rate after 5 min of hydrolysis. The burst is particularly conspicuous for TrCel7B, which reaches a maximal turnover of about 20 s(-1) at 30 °C and conducts about 1200 catalytic cycles per enzyme molecule in the initial fast phase. For TrCel5A and TrCel12A the extent of the burst is 2-300 cycles per enzyme molecule. The availability of continuous data on EG activity allows an analysis of the mechanisms underlying the initial kinetics, and it is suggested that the slowdown is linked to transient inactivation of enzyme on the cellulose surface. We propose, therefore, that the frequency of structures on the substrate surface that cause transient inactivation determine the extent of the burst phase.
Collapse
Affiliation(s)
- Leigh Murphy
- From Roskilde University, NSM, Biomaterials, 1 Universitetsvej, DK-4000 Roskilde, Denmark
- Novozymes A/S, Krogshøjvej 36, DK-2880 Denmark
| | - Nicolaj Cruys-Bagger
- From Roskilde University, NSM, Biomaterials, 1 Universitetsvej, DK-4000 Roskilde, Denmark
| | | | | | | | - Kim Borch
- Novozymes A/S, Krogshøjvej 36, DK-2880 Denmark
| | | | | | - Hirosuke Tatsumi
- International Young Researchers Empowerment Center, Shinshu University, Matsumoto, Nagano 390-8621, Japan
| | - Peter Westh
- From Roskilde University, NSM, Biomaterials, 1 Universitetsvej, DK-4000 Roskilde, Denmark
| |
Collapse
|
23
|
Olsen S, Bohlin C, Murphy L, Borch K, McFarland K, Sweeny M, Westh P. Effects of non-ionic surfactants on the interactions between cellulases and tannic acid: A model system for cellulase–poly-phenol interactions. Enzyme Microb Technol 2011; 49:353-9. [DOI: 10.1016/j.enzmictec.2011.06.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 05/10/2011] [Accepted: 06/18/2011] [Indexed: 11/26/2022]
|
24
|
Praestgaard E, Elmerdahl J, Murphy L, Nymand S, McFarland KC, Borch K, Westh P. A kinetic model for the burst phase of processive cellulases. FEBS J 2011; 278:1547-60. [DOI: 10.1111/j.1742-4658.2011.08078.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
25
|
Baumann MJ, Murphy L, Lei N, Krogh KB, Borch K, Westh P. Advantages of isothermal titration calorimetry for xylanase kinetics in comparison to chemical-reducing-end assays. Anal Biochem 2011; 410:19-26. [DOI: 10.1016/j.ab.2010.11.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 10/28/2010] [Accepted: 11/03/2010] [Indexed: 11/26/2022]
|