Enzyme-Based Organic Synthesis. Cheanyeh Cheng

me a long time to finish a chapter due to my teaching loads, my research works, student and family affairs, and many other trivial things. In fact, I could put all my time and mind on writing this book only after my retirement from school three and half years ago. I really appreciate the tolerant heart of Wiley editor to allow me to finish this book in such a long time. I learned a lot from writing this book, which also opened a new vision for me in the field of microbes and enzyme‐catalyzed organic synthesis. I also deeply understood the meaning of the Chinese proverb “Live and Learn.” What I did and what knowledge I acquired in my 30 years of academic career is only a small part of the field, just like a drop in the ocean. However, I sincerely hope that through this book more people will be interested in the field of enzyme‐catalyzed organic synthesis.

      Life originated from single‐cell microorganisms, and microorganisms that cannot be seen by the human eye have existed on Earth since prehistoric times. Enzymes catalyze diverse chemical reactions in microbial cells from time to time and silently participate in the progress of life. The life phenomena presented by the variety of chemistry involved in the microbial cells is like a solemn and brisk music suite of life. No one would have expected that the relationship between enzymes and the tiny universe of microorganisms is so close and inseparable. Microorganisms are also taken as a cell factory by scientists due to their ability to produce various kinds of useful chemicals for human. However, as a result of the division of labor in science today, chemists, biochemists, biologists, biomedical scientists, biochemical engineers, etc., each use their own specialized scientific expertise to explore this life community, which has led to the difficulty in communication and the inefficient integration among different academic disciplines. Therefore, one of the goals of this book is to enable researchers from different disciplines to communicate and gain consensus to achieve integration.

      The difference between enzyme‐based organic synthesis and traditional organic synthesis is that it uses a highly selective biocatalyst (enzyme), and the enzyme selectivity includes reaction substrate specificity, stereospecificity, and regiospecificity. The selectivity of enzyme also makes the enzyme‐based organic synthesis, particularly the asymmetric synthesis, more easy, convenient, and efficient to produce specialty chemicals. Because the enzyme‐based reaction is usually performed in aqueous solution under mild conditions and in many cases using sustainable renewable substrates, which demonstrates environmentally friendly, enzyme‐based organic synthesis fulfils the requirements of green chemistry. The development of enzymatic biotransformation or microbial fermentation has been over 50 years and has been implemented in numerous industrial applications. The recent advances in enzyme technology, such as protein engineering, site‐specific evolution, metabolic engineering, and enzyme immobilization, have made enzyme‐based organic synthesis more and more competitive with organic synthesis derived from fossil fuels.

This book contains eight chapters. Chapter 1 is an introduction to enzyme, coenzyme, enzyme specificity, and the green chemistry. Chapter 2 is about organic syntheses and their applications using class I oxidoreductases. Chapter 3 focuses on the transamination, glycosyl‐transfer, phosphorylation, and acetyl‐group transfer reactions using class II transferases and their applications. Chapter 4 is about class III hydrolases‐based organic syntheses including hydrolysis reactions of ester bond, amide bond, phosphate esters, epoxides, hydantoins, glycosidic bonds with natural polysaccharides, and their applications. Chapter 5 contains organic syntheses and applications using class IV lyases and concentrates on carbon‐carbon bond formation, carbon‐oxygen bond formation, carbon‐nitrogen bond formation, carbon‐sulfur bond formation, and carbon‐halide bond formation. Chapter 6 describes organic syntheses using class V isomerases including racemases and epimerases, cis–trans isomerase, intramolecular oxidoreductases, intramolecular transferases, intramolecular lyases, and their applications. Chapter 7 presents class VI ligases‐based organic syntheses and their applications focusing on carbon‐oxygen bond formation, carbon‐sulfur bond formation, carbon‐nitrogen bond formation, and carbon‐carbon bond formation reactions. The final Chapter 8 shows two major techniques that could assist the advancements of enzyme‐based organic syntheses in the future: one is the combinatorial chemistry and the other is artificial intelligence.

      The level of contents of this book is medium to high suitable for readers having some basic knowledge of chemistry, organic chemistry, biochemistry, biology, microbiology, and chemical engineering. This book would be a very good reference book for academic researchers and industrial experts working on research and development. This book could also be used as a textbook for one semester course in senior class or graduate school class. Finally, I hope that this book will be able to “throw a brick to attract jade” to elicit truly outstanding books by experts and scholars in this field.

      Cheanyeh Cheng

      Chungli, January 2021

      Acknowledgements

      I would like to thank my parents, Mr. Yet‐Sen Cheng and Mrs. Yen‐In Chen Cheng, for working hard to raise me and for providing me the necessary fees for higher education.

      I would like to thank my former teachers and professors for the education they gave me and for inspiring me so that I continue in the academic field and have a good performance.

      I would like to thank God for giving me the opportunity to write this book.

1 Introduction

      1.1 Discovery and Nature of Enzyme

      Although the historical discovery of enzyme can be sourced back to Spallanzani as early as in 1783 with his noting to the liquefied meat by gastric juice of hawks [1], the discovery of enzyme is in general ascribed to the first “isolation” of an enzyme by two chemists, Anselme Payen and Jean‐François Persoz, who worked at a sugar factory in Paris. In 1833, they obtained a substance from the malt extract called diastase (now known as amylase) that can hydrolyze starch to soluble sugar. Next year, Schwann succeeded in extracting the first enzyme from animal source, pepsin, which digests meat from stomach wall [2]. Later, he also identified trypsin, a peptidase in digestive fluids. By 1837, Jön Berzelius made a remarkable foresight for the catalytic nature of all these biological diastases. In the 1950s, Louis Pasteur acknowledged that sugar fermentation by yeast to produce alcohol is catalyzed by “ferments.” Then, in 1860, Berthelot obtained an alcohol precipitate from yeast that can convert sucrose to glucose and fructose and concluded that there was much such ferment in yeast. Not until 1878, the name enzyme, which means “in yeast,” was proposed by Frederick W. Kühne for these biological catalysts. The catalytic activity of enzyme was proved by Eduard Bücher in 1987 using yeast extract for catalytic alcohol fermentation. One year later, Duclaux proposed that all enzymes should give the suffix “ase” for an easily recognition [3].

The intensive studies of enzymes and proteins were both performed by biochemists in the 1800s. However, not until 1926 the protein nature of enzyme was seriously considered by biochemists that the jack bean urease that was recognized as a protein was first crystallized and recrystallized by James Sumner showing the catalytic ability for hydrolysis of urea to CO₂ and NH₃ [4, 5]. However, the crystal structure of urease which in essence is a nickel‐containing enzyme as known nowadays was obtained by Andrew Karplus from Klebsiella aerogenes [6, 7] almost 70 years later after Sumner’s work. Sumner’s conclusion was widely accepted in the 1930s, after John Northrop and Moses Kunitz crystallized pepsin, trypsin, and other digestive enzymes and found to be proteins.