Enzymes In Carbohydrate Synthesis

Not only assessing the past, present, and future uses of enzymes to synthesize carbohydrates, this volume also illustrates the significance of carbohydrate chemistry and describes how the combination and use of modern enzyme chemistry can advance exploration in the field. Details research at the interface of chemistry and biology for carbohydrate chemistry by demonstrating how to integrate chemical reactions and biological techniques that can be used to synthesize complex bioactive monosaccharides, oligosaccarides, and glycoconjugates. Of particular interest are chapters by George Whitesides and Chi-Huey Wong covering the use of enzymes in monosaccharide synthesis, and Hindsgaul, Thiem, Nilsson, and Whitesides describing the use of activated sugar nucleosides and glycosyltransferases in the synthesis of oligosaccharides and polysaccharides.

In this thesis, the synthetic utility of enzymes as catalysts for carbohydrate synthesis was explored. Sialic acid aldolase was applied to make high-carbon monosaccharides. This study included the discovery that re face attack on the acceptor carbonyl was observed toward scL-sugar substrates, instead of si face attack toward scD-sugar substrates; i.e., the opposite stereoselectivity occurred with enantiomeric substrates. Examination of the product distribution during the course of enzymatic reactions revealed that the stereoselectivity is thermodynamically controlled. CTP: CMP-3-deoxy- scD-manno-octulosonate cytidylyltransferase (CMP-KDO synthetase) was prepared for the synthesis of cytidine 5'-monophospho-3- deoxy- scD-manno-octulosonic acid (CMP-KDO) and analogs. The nature product of the enzyme, CMP-KDO, is unstable. Of several KDO analogs tested as substrates for this enzyme, 5-fluoro-2-keto-3,5-dideoxyoctulosonic acid (5-FKDO) was found to be a good substrate. The synthesis and characterization of the product, CMP-5-FKDO, represents the first stable CMP-KDO analog prepared enzymatically to date. A mechanism was proposed to explain the instability of CMP-KDO. A sialyl Lewis x dimer was synthesized enzymatically in three steps from an N-linked oligosaccharide prepared from egg yolk. Treatment of delipidated hen egg yolk with the protease orientase and neuraminidase gave a dimeric N- acetyllactosamine-containing oligosaccharide linked to asparagine. Addition of sialic acid and fucose catalyzed by [alpha]-2,3-sialyltransferase and [alpha]-1,3-fucosyltransferase provided the dimeric sialyl Lewis x, an active inhibitor of E-selectin with IC50 of 0.75 mM. In the enzymatic sulfation of polyfunctional biomolecules, 3'-phosphoadenosine-5'-phospho sulfate (PAPS) is a key intermediate and cofactor. In order to accomplish the regioselective sulfation of oligosaccharides, ATP sulfurylase, APS kinase, and Nod factor sulfotransferase were cloned and overexpressed in Escherichia coli. The first two enzymes were used in the mmol-scale synthesis of PAPS with regeneration of ATP. Additionally, PAPS was further used in the enzymatic sulfation of N,N'-diacetylchitobiose catalyzed by a recombinant Nod factor sulfotransferase, which was coupled with regeneration of PAPS from 3'-phosphoadenosine-5'-phosphate (PAP).

This book focuses on the latest research and new techniques in the field of functional carbohydrate-related enzymes. Carbohydrates are a key form of energy for most organisms. The “good” carbohydrates generally refer to functional carbohydrates. In addition to the low or moderate energy-supplying function, they have more nutritious value than traditional carbohydrates and some of them also have health-promoting effects especially prebiotic actions. Several enzymatic methods for the synthesis of such carbohydrates have been discovered and developed in the recent decades, providing a new range of application areas for these novel enzymes. This book addresses the classification of functional carbohydrate-related enzymes and the overall development in food enzyme in Chapter 1. Chapters 2-5 describe the isomerases or epimerases involved in the production of rare sugars, such as D-allulose, D-mannose, D-tagatose, and D-allose. While the studies of the enzymes related to fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS) dominate the scientific literature in the field of enzymatic production of health-functional oligosaccharides, some enzymes also show promise for the emerging oligosaccharide production, which are introduced in Chapters 6-8. Chapters 9-12 summarize the new enzymatic technologies and applications in fructan- and glycan-related industries. The last Chapter gives an overall prospective on the trends of enzymatic functional carbohydrate production. This book is a valuable resource for researchers and graduate students in the fields of biotechnology, enzyme engineering, and carbohydrate production, as well as the health industry.

Carbohydrate bioengineering is a rapidly expanding field with many applications in medicine and industry. Presenting state-of-the-art research, Carbohydrate Bioengineering: Interdisciplinary Approaches brings together international experts on many different aspects of this burgeoning topic. Coverage includes: the engineering of glycosidases for constructive purposes; structure-function studies and protein engineering of carbohydrate-active enzymes; chemo-enzymatic carbohydrate synthesis; and trends emerging from comprehensive work on genomes and glycomes. This timely publication will be welcomed by all those needing access to the latest research in the field, including practitioners in the medicinal, chemical, food and pharmaceutical areas.

Modern Methods in Carbohydrate Synthesis presents in one volume a sequence of chapters leading from classical methods through to today's newest state-of -the-art technology for oligosaccharide synthesis. It places particular emphasis on the most recent breakthroughs in the field, including emerging technologies for both oligosaccharide and glycoconjugate synthesis. Chapters describing the synthesis of increasingly important glycosidic linkage analogs, as well as the oligosaccharides containing derivatives and analogs of natural sugars are included. While chemical-synthetic methods constitute the major part of the book, completing the volume is a section on the rapidly expanding and important field of enzymatic synthesis, also covering combined chemical and enzymatic synthesis. Chapters are written by leading experts in the field. Wherever possible, methods of synthesis are provided in sufficient detail to allow the reader to implement the techniques described. More than 1700 references are provided in the 21 chapters comprising the book. This volume should provide a wealth of information to a large number of synthetic organic chemists, medicinal chemists, protein chemists, biochemists, glycobiologists and cell biologists, including students in these fields.

Carbohydrate-active enzymes are responsible for both biosynthesis and the breakdown of carbohydrates and glycoconjugates. They are involved in many metabolic pathways; in the biosynthesis and degradation of various biomolecules, such as bacterial exopolysaccharides, starch, cellulose and lignin; and in the glycosylation of proteins and lipids. Carbohydrate-active enzymes are classified into glycoside hydrolases, glycosyltransferases, polysaccharide lyases, carbohydrate esterases, and enzymes with auxiliary activities (CAZy database, www.cazy.org). Glycosyltransferases synthesize a huge variety of complex carbohydrates with different degrees of polymerization, moieties and branching. On the other hand, complex carbohydrate breakdown is carried out by glycoside hydrolases, polysaccharide lyases and carbohydrate esterases. Their interesting reactions have attracted the attention of researchers across scientific fields, ranging from basic research to biotechnology. Interest in carbohydrate-active enzymes is due not only to their ability to build and degrade biopolymers—which is highly relevant in biotechnology—but also because they are involved in bacterial biofilm formation, and in glycosylation of proteins and lipids, with important health implications. This book gathers new research results and reviews to broaden our understanding of carbohydrate-active enzymes, their mutants and their reaction products at the molecular level.

There is a vast and often bewildering array of synthetic methods and reagents available to organic chemists today. The Best Synthetic Methods series allows the practising synthetic chemist to choose between all the alternatives and assess their real advantages and limitations. Each chapter in Carbohydrates details a particular theme associated with carbohydrate synthesis. A brief review of the subject area is provided, but the emphasis in all cases is on describing efficient practical methods to effect the transformations described. In order for the roles of carbohydrates to be thoroughly analysed and assessed, glycobiologists require access to defined target carbohydrates in useful quantities. Thus carbohydrates and glycoconjugates are now recognized as important targets for total synthesis programmes and it is essential to develop efficient regio- and stereoselective methods for the synthesis of carbohydrates. Whilst carbohydrates can sometimes be isolated from natural sources, synthetic strategies often offer the advantage of allowing access to larger quantities of material as well as entry to analogues of the natural carbohydrates. The latest volume in the long standing Best Synthetic Methods series Clear chapter by chapter breakdown of carbohydrate synthesis themes with examples of good practical methods for common carbohydrate syntheses

Synthesis of Carbohydrates Through Biotechnology describes rapid developing and cutting-edge new technologies in glycoscience. These new approaches combine advantages of molecular biology, genetic engineering and chemistry, and provide access to synthetic carbohydrates.

Carbohydrate Chemistry provides review coverage of all publications relevant to the chemistry of monosaccharides and oligosaccharides in a given year. The amount of research in this field appearing in the organic chemical literature is increasing because of the enhanced importance of the subject, especially in areas of medicinal chemistry and biology. In no part of the field is this more apparent than in the synthesis of oligosaccharides required by scientists working in glycobiology. Clycomedicinal chemistry and its reliance on carbohydrate synthesis is now very well established, for example, by the preparation of specific carbohydrate- based antigens, especially cancer-specific oligosaccharides and glycoconjugates. Coverage of topics such as nucleosides, amino-sugars, alditols and cyclitols also covers much research of relevance to biological and medicinal chemistry. Each volume of the series brings together references to all published work in given areas of the subject and serves as a comprehensive database for the active research chemist Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading authorities in the relevant subject areas, the series creates a unique service for the active research chemist, with regular, in-depth accounts of progress in particular fields of chemistry. Subject coverage within different volumes of a given title is similar and publication is on an annual or biennial basis.