Enzymes in organic solvents get on with business

Abstract

Methods in Non-Aqueous Enzymologyedited by Munishwar Nath Gupta, Birkhauser, Berlin, 2000.US$ 155.00 (hbk) US$ 69.95 (pbk)ISBN 3 764 3 5803 3Although many research groups throughout the world have studied the application of enzymes for catalysis of reactions in non-aqueous media for at least 20 years, it is still very much an art for many researchers. This book of protocols is an attempt to collate some methods of practical use. The premise of this book, as suggested in the preface, is to encourage more researchers to explore the use of enzymes for biocatalysis in non-aqueous systems by motivating them and providing clear and concise protocols.There has been a flood of published material on this subject, including several books but this collection of protocols presents useful techniques to the scientific community. Many non-aqueous enzymatic reactions have been optimized, but the book focuses primarily on work with lipases. Of the ten protocol chapters discussing reactions in organic media, seven either exclusively cover or otherwise include lipase-catalyzed reactions. Although this is not representative of the broad application of the non-aqueous enzymology researched to date, the chapters do describe many different reactions that can be performed. Two chapters discuss chiral resolutions: one covers immobilization methods and the algorithm for the calculation of enantiomeric ratio and enantiomeric excess; the other covers the impact of water activity on these same types of reactions with reference to a website that provides a ‘calculator’ for the determination of the enantiomeric parameters.Several chapters contain clear motivations and high quality protocols. The chapter on fat and oil processing provides an excellent background to the topic, with a clear description of when and why the protocols presented would be useful. Likewise, the troubleshooting section concisely details some practical hints concerning the reactor design and catalyst preparation. There is a useful chapter on enzyme selectivity in organic media, which describes the influence of the type of solvent on the function of various enzymes, and although it lacks depth into the five enzymatic reactions described, it is well referenced for those interested in further information. A chapter on sugar transformations describes the use of organic solvents to increase the applicability of enzymes to catalyze otherwise difficult reactions.Another chapter discusses the use of reversed micelles for the acylation of proteins – specifically the modification of RNaseA and its consequent purification. Reversed micelles have been studied extensively as a functional media for several enzymatic reactions, as well as the selective extraction of enzymes from a mixture of proteins. The protocols in this chapter describe an interesting and unique application for reversed micelles, which might not be easily extended to the use of reversed micelles for other enzyme-catalyzed reactions.Some of the background sections are weak at best, and some of the troubleshooting sections seem more like a discussion. In addition, there are some chapters with protocols that are not realistic. For example, the chapter on organic phase biosensors is very interesting but it is doubtful that many would succeed in repeating the experiments without specialized training in opto-acoustic sensing. Likewise, immobilization methods are described in most of the chapters but only one chapter is dedicated exclusively to immobilization of lipases and compares the effectiveness of several approaches.For beginners to non-aqueous enzymology, the book provides a collection of well-referenced approaches that give direction in a subset of areas within the field. It is probably most helpful to those who have attempted reactions in organic solvents without achieving the anticipated results – alternative approaches covered in the book might improve their success. In the preface, the editor states ‘Science is about being able to repeat what somebody else has done.’ Indeed, the protocols are, for the most part, descriptions of reactions and methods that have been carried out in the authors’ laboratories. So, although the book contains successful experiences, the application to reaction systems other than those described is not explicit. Despite some weaknesses, I am quite certain that this book will be a positive addition to many libraries and helpful for those who are curious and interested enough to explore non-aqueous systems for their experiments.