Redox Biocatalysis E-Book

Daniela Gamenara

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 787

Veröffentlichungsjahr: 2012

Beschreibung

Paves the way for new industrial applications using redox biocatalysis Increasingly, researchers rely on the use of enzymes to perform redox processes as they search for novel industrial synthetic routes. In order to support and advance their investigations, this book provides a comprehensive and current overview of the use of redox enzymes and enzyme-mediated oxidative processes, with an emphasis on the role of redox enzymes in chemical transformations. The authors examine the full range of topics in the field, from basic principles to new and emerging research and applications. Moreover, they explore everything from laboratory-scale procedures to industrial manufacturing. Redox Biocatalysis begins with a discussion of the biochemical features of redox enzymes as well as cofactors and cofactor regeneration methods. Next, the authors present a variety of topics and materials to the research and development of full-scale industrial applications, including: * Biocatalytic applications of redox enzymes such as dehydrogenases, oxygenases, oxidases, and peroxidases * Enzyme-mediated oxidative processes based on biocatalytic promiscuity * All the steps from enzyme discovery to robust industrial processes, including directed evolution, high-throughput screening, and medium engineering * Case studies tracing the development of industrial applications using biocatalytic redox reactions Each chapter ends with concluding remarks, underscoring the key scientific principles and processes. Extensive references serve as a gateway to the growing body of research in the field. Researchers in both academia and industry will find this book an indispensable reference for redox biotransformations, guiding them from underlying core principles to new discoveries and emerging industrial applications.

Leseprobe

Contents

Cover

Title Page

Copyright

Preface

Chapter 1: Enzymes Involved in Redox Reactions: Natural Sources and Mechanistic Overview

1.1 MOTIVATION: GREEN CHEMISTRY AND BIOCATALYSIS

1.2 SOURCES OF BIOCATALYSTS

1.3 OVERVIEW OF REDOX ENZYMES

1.4 CONCLUDING REMARKS

REFERENCES

Chapter 2: Natural Cofactors and Their Regeneration Strategies

2.1 TYPES OF NATURAL COFACTORS—MECHANISMS

2.2 COFACTOR REGENERATION

2.3 CONCLUDING REMARKS

REFERENCES

Chapter 3: Reactions Involving Dehydrogenases

3.1 GENERAL CONSIDERATIONS

3.2 REDUCTION OF CARBONYL GROUPS

3.3 RACEMIZATION AND DERACEMIZATION REACTIONS

3.4 PREPARATION OF AMINES

3.5 REDUCTION OF C–C DOUBLE BONDS

3.6 OXIDATION REACTIONS

3.7 DEHYDROGENASE-CATALYZED REDOX REACTIONS IN NATURAL PRODUCTS

3.8 CONCLUDING REMARKS

REFERENCES

Chapter 4: Reactions Involving Oxygenases

4.1 MONOOXYGENASE-CATALYZED REACTIONS

4.2 DIOXYGENASE-CATALYZED REACTIONS

4.3 CONCLUDING REMARKS

REFERENCES

Chapter 5: Reactions Involving Oxidases and Peroxidases

5.1 OXIDASE-CATALYZED REACTIONS

5.2 PEROXIDASE-CATALYZED REACTIONS

5.3 CONCLUDING REMARKS

REFERENCES

Chapter 6: Hydrolase-Mediated Oxidations

6.1 HYDROLASE PROMISCUITY AND IN SITU PERACID FORMATION. PERHYDROLASES VS. HYDROLASES. OTHER PROMISCUOUS HYDROLASE-MEDIATED OXIDATIONS

6.2 HYDROLASE-MEDIATED BULK OXIDATIONS IN AQUEOUS MEDIA (E.G., BLEACHING, DISINFECTION, ETC.)

6.3 LIPASE-MEDIATED OXIDATIONS: PRILESHAJEV EPOXIDATIONS AND BAEYER–VILLIGER REACTIONS

6.4 HYDROLASE-MEDIATED OXIDATION AND PROCESSING OF LIGNOCELLULOSIC MATERIALS

6.5 CONCLUDING REMARKS

REFERENCES

Chapter 7: Bridging Gaps: From Enzyme Discovery to Bioprocesses

7.1 CONTEXT

7.2 ENZYME DIRECTED EVOLUTION AND HIGH-THROUGHPUT-SCREENING OF BIOCATALYSTS

7.3 SUCCESSFUL CASE: BAKER'S YEAST REDOX ENZYMES, THEIR CLONING, AND SEPARATE OVEREXPRESSION

7.4 WHOLE-CELLS VS. ISOLATED ENZYMES: MEDIUM ENGINEERING

7.5 BEYOND: MULTISTEP DOMINO BIOCATALYTIC PROCESSES

7.6 CONCLUDING REMARKS

REFERENCES

Chapter 8: Industrial Applications of Biocatalytic Redox Reactions: From Academic Curiosities to Robust Processes

8.1 MOTIVATION: DRIVERS FOR INDUSTRIAL BIOCATALYTIC PROCESSES

8.2 KEY ASPECTS IN INDUSTRIAL BIOCATALYTIC PROCESSES

8.3 INDUSTRIAL BIOCATALYTIC REDOX PROCESSES: FREE ENZYMES

8.4 INDUSTRIAL BIOCATALYTIC REDOX PROCESSES—WHOLE-CELLS: THE “DESIGNER BUG” CONCEPT AND BEYOND (METABOLIC ENGINEERING)

8.5 CONCLUDING REMARKS AND FUTURE PERSPECTIVES

REFERENCES

Index

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Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada.

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Library of Congress Cataloging-in-Publication Data:

Redox biocatalysis : fundamentals and applications / Daniela Gamenara … [et al.]. p. cm. Includes bibliographical references and index. ISBN 978-0-470-87420-2 (cloth) 1. Environmental chemistry. 2. Environmental chemistry–Industrial applications. 3. Oxidation-reduction reaction. 4. Enzymes. I. Gamenara, Daniela, 1964– TD193.R43 2012 660.6′34–dc23 2012025734

PREFACE

The use of enzymes for redox processes has gained an increasing interest in the last decades, becoming in many cases “the first choice” for scouting novel industrial synthetic routes. This has been realized by solving issues related to cofactor regeneration, often needed for these enzymes, together with the developments in molecular biology areas that have enabled the provision of enzymes in large and reproducible scale in a fermentative sustainable manner. The development of environmentally sound synthetic protocols is mandatory in this century and, in this regard, oxidoreductases are ideally suited to the task, providing efficient and green alternatives to conventional synthetic procedures. This is particularly remarkable in oxidative processes, where oxidases and oxygenases perform clean and selective oxidations by activation of molecular oxygen with no need of heavy metals or expensive chemocatalysts. On the reductive side, these enzymes find ample application in the industry and academia for the generation of enantioenriched compounds.

This book provides a comprehensive and updated overview on the use of redox enzymes and enzyme-mediated oxidative processes. Chapters 1 and 2 provide an introduction on biochemical features of redox enzymes, together with aspects related to cofactors, and cofactor regeneration methods. Chapters 3–5 describe in detail the biocatalytic applications of different redox enzymes, namely, dehydrogenases (Chapter 3), oxygenases (Chapter 4), and oxidases and peroxidases (Chapter 5). Enzyme-mediated oxidative processes based on biocatalytic promiscuity (e.g., of hydrolases) are covered in Chapter 6. Chapter 7 focuses on the necessary steps starting from the discovery of a certain enzyme with a catalytic activity to a robust industrial process (e.g., directed evolution, high-throughput-screening methods, and medium engineering). Last but not least, Chapter 8 provides an overview on industrial cases using oxidoreductases, already commercialized or close to, showing that academic research is ending up with successful cases at the industrial arena. Overall, we believe that our contribution may well serve as a complete and first approach to academic and industrial research groups in the field of redox biocatalysis. It is our hope that readers will find this book an attractive and useful tool.

Finally, we would like to acknowledge Ms. Anita Lekhwani, Senior Acquisitions Editor at John Wiley & Sons, as well as the whole editorial team for the trust, hard work, interest, and patience that they have put into this project.

DANIELA GAMENARA GUSTAVO SEOANE PATRICIA SAENZ-MÉNDEZ PABLO DOMÍNGUEZ DE MARÍA

Montevideo, Uruguay, and Aachen, Germany,December 2011

CHAPTER 1

Enzymes Involved in Redox Reactions: Natural Sources and Mechanistic Overview

1.1 MOTIVATION: GREEN CHEMISTRY AND BIOCATALYSIS

Current environmental concerns are pressuring Chemical and Pharmaceutical industries to develop novel synthetic approaches that may operate under more benign conditions. This trend has paramounted the appearance of the “Green Chemistry” as a core discipline, with an increasing importance both in academia and industry. In a nutshell, Green Chemistry—as well as Green Engineering—has been compiled under several principles, as stated by Anastas and Zimmerman, and Tang and coworkers [1,2]. From the Green Chemistry approach, these principles are gathered in the acronym “PRODUCTIVELY”:

Prevent wastesRenewable materialsOmit derivatization stepsDegradable chemical productsUse safe synthetic methodsCatalytic reagentsTemperature, ambient pressureIn-process monitoringVery few auxiliary substancesE-factor, maximize feed in productLow toxicity of chemical productsYet, it's safe

On the other hand, from the Green Engineering perspective, those principles are grouped in the acronym “IMPROVEMENTS”:

Inherently nonhazardous and safeMinimize material diversityPrevention instead of treatmentRenewable material and energy inputsOutput-led designVery simpleEfficient use of mass, energy, space, and timeMeet the needEasy to separate by designNetworks for exchange of local mass and energyTest the life cycle of the designSustainability throughout product life cycle

In this respect, the use of enzymes and whole-cells as biocatalysts for synthetic purposes (White Biotechnology) is an increasingly important field that may fit, in many cases, with all or some of these Green Chemistry principles. In fact, enzymatic living processes are often conducted under extremely mild reaction conditions, for example, neutral pH, or no need of high pressures or temperatures, which may provide energy savings for the overall process. Albeit biocatalytic processes are not always in line with all Green Chemistry principles (e.g., wastewater generation after downstream processing), they often provide advantages when compared to other chemical approaches. These assets have triggered the development of biocatalysis, reaching today the status of established technology, and occupying a prominent role as “synthetic organic chemistry tool” [3–16].

1.2 SOURCES OF BIOCATALYSTS

In the early stages of biocatalysis, plant tissues, and animal organs were the most important sources of enzymes, representing in the 1960s about 70% of the biocatalysts used for synthetic purposes [17,18]. The trend rapidly changed, and 20 years later most of industrially used enzymes were already being obtained from microbial sources. There are still some commercially available enzymes from animal origin, mostly hydrolases, accounting for approximately 10% of total of enzymes used at industrial level [19]. In this group, catalase from liver (EC 1.11.1.6), triacylglycerol lipase (EC 3.1.1.3), and trypsin from pancreas (EC 3.4.21.4) are the most relevant animal enzymes currently used, mainly in food industries [20,21]. Enzymes from vegetable origins, such as papain and cysteine proteases from papaya latex (Carica papaya, Carica candamarcensis), have industrial relevance as well, representing almost 5% of the market [17,22,23]. Other enzymes, such as invertase [24], peptidases [25], and acid phosphatase [26] are produced in vivo in plant cell cultures, but their production involves highly complex and expensive processes, thus showing a limited use at industrial scale [27]. However, some glycoenzymes, such as glutamine synthetase, which are not easily produced as recombinant proteins in microbial hosts, are suitable candidates for the in vitro production with adequate cell lines [28].

While the origin of the biocatalysts can obviously be highly diverse, microorganisms are a rich source of enzymes, and thus their use as whole-cells, or the use of isolated microbial enzymes as biocatalysts has been vastly reported in the literature. Since the 1960s microbial enzymes have been replacing the biocatalysts from other origins, and to date, represent over 90% of the total market [17]. Currently, the exploitation of microbial diversity in the quest for new enzymes with novel activities is one of the major research goals in biocatalysis. This is complemented by the rational design of enzymes, and their production and overexpression in adequate microbial hosts through genetic engineering techniques [29]. Remarkably, the use of recombinant microorganisms was originally envisaged for the production of proteins of therapeutic interest. However, its real advantage is the reduction of production costs for a wide variety of proteins, especially when compared with the fermentation of wild-type microorganisms [30].

1.2.1 Plants and Animals as Sources of Redox Biocatalysts

As stated above, animal and plant tissues are classic sources of biocatalysts. Enzymes from higher eukaryotes have been traditionally used in food industry as food additives, in fruit processing or in wine production, as well as pharmaceutical additives. Some examples are the use of papain, lipoxygenase (LOX), or pepsin in processes already developed in the 1980s, which are still widely used [31,32]. Many hydrolases such as porcine pancreas lipase (PPL), pig liver esterase (PLE), or chymotrypsin and trypsin have been isolated from animal tissues, and have been widely used as biocatalysts [33]. Oxidoreductases (EC 1.-), hydrolases (EC 3.-), lyases (EC 4.-), and isomerases (EC 5.-) provide the vast majority of examples of higher eukaryotic enzymes for industrial applications, and no commercial processes using plant or animal enzymes from other enzyme classes have been reported [32].

Some of these animal or plant tissues can provide high amounts of enzymes (up to 1% of wet weight), for example, pancreatic enzymes or others involved in specific metabolisms (from liver or heart), or enzymes located in plant reserve organs such as seeds. However, recovering these enzymes from tissues is often cumbersome, and thus alternative sources must be found for their production at large scale for synthetic purposes. In addition, in case of pancreatic enzymes, after the discovery of pancreas as insulin-producing organ in 1921, the tissue became very expensive as a source of enzymes for biocatalysis. The enzymes that are still obtained from pancreas—trypsin and chymotrypsin—are actually by-products in insulin metabolism. Furthermore, nowadays insulin is mostly produced by recombinant microorganisms (Escherichia coli or yeast cells), as other enzymes originally obtained from pancreas do as well.

Higher eukaryotic enzymes usually need to be isolated and purified, or cloned and overexpressed in suitable hosts in order to obtain sufficient amounts for biocatalytic applications. The use of synthetic host-adopted genes and codon-optimized strains, and the development of highly successful eukaryotic expression systems such as the yeasts and , have enabled the production of large quantities of eukaryotic enzymes within a short time [34].