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Food proteins — Improvement through chemical and enzymatic modification
Topics in Enzyme and Fermentation Biotechnology, Volume 2 Editor, A. Wiseman
Ellis Horwood, Chichester, 1978, 308 pp., £15.00/$31.80
In a field as extended and diverse as that of biotechnology which encompasses microbiology, theoretical enzymology and chemical engineering, the danger facing any book entitled 'Topics in . . . ' is that of unconnected diversity. Although the interdisciplinary approach stressed by Dr Wiseman in his introduction to this second volume may indeed be creative, it could be argued that the creative readership would be more responsive to a broad-spectrum journal than to a relatively expensive book with inevitably limited coverage. However, this collection of topics is part of a continuing series which promises to have considerable aggregate value. The subjects are well chosen and include some valuable reviews covering the literature up to the end of 1976; not absolutely topical perhaps, but a reasonable vantage point. The review of 'Enzymes Immobilised on Inorganic Supports' by Drs Kent, Rosevear and Thomson is particularly timely in view of the increasing interest in alternatives to costly and mechanically inadequate organic supports. The account covers most of the methods of coupling or adsorbing enzymes to derivatized glass and other supports as well as the mathematical approaches to the modelling of reactor function. Much of this is available elsewhere but not in such a complete and concise format. The review also includes a summary of applications, which helps to bring up to date previous reviews such as that by Zaborsky. A summary of recent work on 'Enzyme Electrodes and Enzyme Based Sensors' is provided by Professor Barker and Dr Somers and is a useful introduction to the rapidly growing number of applications of enzyme specificity to analytical problems. Oxygen, pH, carbon dioxide and ammonia electrodes are considered as well as amperometric systems and enzyme thermistors. The clinically important 'Antibiotic Inactivating Enzymes' are discussed by Dr Melling in an account which is really confined to the better characterized ~-lactamases, the aminoglycoside-
70
inactivating enzymes and chloramphenicol acyl transferases. Other types of antibiotic and their modification are not considered. Substrate specificity is dealt with but enzyme chemistry, structure and function (e.g. the conformational peculiarities of ~3-1actamases) which are of particular relevance in the light of the recent discovery of powerful/3-1actamase inhibitors are not. 'The Biological Treatment of Aqueous Wastes' is the subject of an extensive treatise by M. A. Winkler and A. Thomas. The emphasis is on engineering practice rather than microbiology or biochemistry and there is much discussion of empirical relationships involved in oxygen demand calculations and the modelling of activated sludge and percolation processes. The main concern of this account is with sewage and, in general terms, fermentation waste. Although some consideration is given to nitrification and denitrification, there is no mention of more specific pollutants (such as heavy metals or chlorinated hydrocarbons) which pose special environmental problems which in turn may be amenable to future modified enzyme technology. Of great importance yet notoriously unpredictable in practice, 'Enzyme Stabilisation' is the subject of the final chapter by Dr Wiseman. The general approaches to stabilization, i.e. additives, immobilization and chemical crosslinking are considered. A wealth of examples is given but l would have liked to see more attention paid to theoretical aspects of the problem such as hydrophilic/hydrophobic balance in relation to tertiary structure, the thermodynamics and kinetics of unfolding processes and the relationship of transition state to ground-state structure in enzymes. In general, this book is well produced, has a useful index and is largely free of errors (although the positively charged azide functions on p. 51 should not go unchallenged). It is certainly a useful addition to the library of all research workers interested in applied enzymology and students of chemical engineering should find Chapters 2 and 5 particularly interesting. Those with specific interests in antibiotics or pollution control may be better served by more specialized texts.
EnzymeMicrob. Technol., 1979, vol. 1, January
R. A. G. Smith
Food Proteins - Improvement through Chemical and Enzymatic Modification Editors: Robert E. Feeney and John R. Whitaker American Chemical Society, Washington, DC, 1977, $23.00
This volume is the 160th in the valuable 'Advances in Chemistry Series' and consists of papers presented at a symposium in Mexico City in late 1975: the advances are therefore not the most recent. However, the editors (perhaps more aptly described as 'compilers' since there is little evidence in the elimination of duplicated information of the contributions having been edited) state that many of the new ideas presented appear to be 'blue sky' thinking which will challenge food scientists and technologists in the future. Challenges are always opportunities and this volume will prove stimulating to those scientists and technologists involved in the extension and development of the food protein industry. Since almost all proteins are either foodstuffs already or would be foodstuffs if made acceptable and/or safe for consumption this volume deals with almost all proteins. Chemical and enzymatic methods of modifying proteins are kept separate: Feeney contributes a review of the chemical methods available for modifying proteins in general and the effects such modifications have on their acceptability and properties. Gross deals specifically with the rare amino acid lysinoalanine, known from the microbial products nisin and subtilin and recently detected in foodstuffs subjected to alkaline conditions. Its physiological effects are unknown. Meyer and Williams review such work as has been done on the modification of soy protein products. Finally in this section Ryan deals concisely and readably with determinants of the functional properties of proteins and protein derivatives on foods. This more theoretical paper would have fitted more appropriately before the two shorter papers on specific topics. The greater part of the book is devoted to chapters on the enzymatic modification of proteins or protein sources. Whitaker introduces the subject in a wide-ranging paper which sets the scene for the following
Book Reviews chapters. Fujimaki, Arai and Yamashita review protein degradation and re-synthesis in the so-called 'plastein reaction' which allows the introduction of amino acids lacking in the original protein as well as converting undesirably textured or flavoured proteins into a bland, acceptable material. In a particularly valuable chapter, Richardson reviews work on functionality changes in proteins following enzymatic action. This introduces enzymic involvement in such processes as the tenderizing of meats both naturally and artifically, the changes occurring in dough during bread making and the alteration of milk proteins which occurs during
cheese preparation and maturation. The last two chapters deal with enzymatic methods of improving the acceptability of foodstuffs containing proteins by eliminating undesirable materials without altering the proteins themselves: Phaff's contribution is a thorough and detailed account of the structure of yeast cell walls and of the enzymes capable of degrading them and Liener deals with the removal of a mixed bag of toxic or undesirable materials ranging from cyanogens, through flatulenceproducing sugars in beans and lactose in milk to phytic acid in seed flours. The challenges presented in these chapters are severe: little is known of
the toxicity or otherwise of chemically-modifed proteins or of the plasteins, the plastein reaction will improve the acceptability of novel proteins but it will do nothing practical to improve the nutritional quality of dietary proteins until the rarer essential amino acids are available at economic prices and many of the enzymes mentioned are not commercially available in bulk, at least. Enzyme technology seems to have been applied to few of the problems presented, some of which should yield to ingenuity in enzyme or cell immobilization coupled with suitable reactor design. C. Bucke
Opportunities for collaboration in biochemical engineering The National Science Foundation (NSF) of the United States and the Korea Science and Engineering Foundation (KOSEF) of the Republic of Korea have selected biochemical engineering as a priority area for consideration and support under the United States-Republic of Korea Cooperative Science Program. A joint advisory committee, convened in August 1977, recommended cooperative research activities be developed in these areas: (1) Food Resources (use of cellulosic biomass for single cell protein production, single cell protein through photosynthesis, and improved methods of conservation and management of renewable food resources). (2) Pharmaceuticals and Fine Chemicals ( b i o t r a n s f o r m a t i o n microbial and enzymatic, fermentation technology problems, recovery and purification processes, cellular metabolites as potentially useful biologically active agents, and new techniques and developments for production of fine chemicals).
(3) Energy Resources Development and Bioconversion (biomass resources, methane production, carbohydrate production from biomass, utilization of carbohydrate from biomass, utilization of photosynthetic microorganisms, and systematic study of effective utilization, conservation and management of renewable and non-renewable energy resources). (4) Enzyme Technology (applications of enzyme technology in food, energy, chemical production, and environmental analysis and control; elements of enzyme technology in production of enzymes, isolation and purification processes, structure/ function relations, immobilization of enzymes and ceils, reactor design of enzymes and whole cells, and coenzyme regeneration). (5) Biological Waste Treatment for Pollution Abatement and Utilization of Byproducts (utilization of waste water and waste water sludges, utilization of feedlot waste, exploration of scale-up methods for waste water treatment, and regional waste water treatment systems).
(6) Microbial Strain D e v e l o p m e n t Physiology and Genetics (strain improvement for cellulose producing organisms, strain development for nucleosides/nucleotides production, genetics of the biochemical basis of nitrogen fixation by microorganisms, recombinant DNA research, and mechanisms of mutagenesis). NSF and KOSEF encourage US and Korean investigators whose work would be substantially advanced through collaboration and who may wish jointly to design and direct research in one of these areas to contact the programme managers for further information: Allen Holt Division of International Programs, National Science Foundation, Washington, D.C. 20550, USA Suhn Gun Kim Korea Science and Engineering Foundation, P.O. Box 124, Cheong Ryang 130, Seoul, Korea
Enzyme Microb. Technol., 1979, vol. 1, January
71
Ellis Horwood, Chichester, 1978, 308 pp., £15.00/$31.80
In a field as extended and diverse as that of biotechnology which encompasses microbiology, theoretical enzymology and chemical engineering, the danger facing any book entitled 'Topics in . . . ' is that of unconnected diversity. Although the interdisciplinary approach stressed by Dr Wiseman in his introduction to this second volume may indeed be creative, it could be argued that the creative readership would be more responsive to a broad-spectrum journal than to a relatively expensive book with inevitably limited coverage. However, this collection of topics is part of a continuing series which promises to have considerable aggregate value. The subjects are well chosen and include some valuable reviews covering the literature up to the end of 1976; not absolutely topical perhaps, but a reasonable vantage point. The review of 'Enzymes Immobilised on Inorganic Supports' by Drs Kent, Rosevear and Thomson is particularly timely in view of the increasing interest in alternatives to costly and mechanically inadequate organic supports. The account covers most of the methods of coupling or adsorbing enzymes to derivatized glass and other supports as well as the mathematical approaches to the modelling of reactor function. Much of this is available elsewhere but not in such a complete and concise format. The review also includes a summary of applications, which helps to bring up to date previous reviews such as that by Zaborsky. A summary of recent work on 'Enzyme Electrodes and Enzyme Based Sensors' is provided by Professor Barker and Dr Somers and is a useful introduction to the rapidly growing number of applications of enzyme specificity to analytical problems. Oxygen, pH, carbon dioxide and ammonia electrodes are considered as well as amperometric systems and enzyme thermistors. The clinically important 'Antibiotic Inactivating Enzymes' are discussed by Dr Melling in an account which is really confined to the better characterized ~-lactamases, the aminoglycoside-
70
inactivating enzymes and chloramphenicol acyl transferases. Other types of antibiotic and their modification are not considered. Substrate specificity is dealt with but enzyme chemistry, structure and function (e.g. the conformational peculiarities of ~3-1actamases) which are of particular relevance in the light of the recent discovery of powerful/3-1actamase inhibitors are not. 'The Biological Treatment of Aqueous Wastes' is the subject of an extensive treatise by M. A. Winkler and A. Thomas. The emphasis is on engineering practice rather than microbiology or biochemistry and there is much discussion of empirical relationships involved in oxygen demand calculations and the modelling of activated sludge and percolation processes. The main concern of this account is with sewage and, in general terms, fermentation waste. Although some consideration is given to nitrification and denitrification, there is no mention of more specific pollutants (such as heavy metals or chlorinated hydrocarbons) which pose special environmental problems which in turn may be amenable to future modified enzyme technology. Of great importance yet notoriously unpredictable in practice, 'Enzyme Stabilisation' is the subject of the final chapter by Dr Wiseman. The general approaches to stabilization, i.e. additives, immobilization and chemical crosslinking are considered. A wealth of examples is given but l would have liked to see more attention paid to theoretical aspects of the problem such as hydrophilic/hydrophobic balance in relation to tertiary structure, the thermodynamics and kinetics of unfolding processes and the relationship of transition state to ground-state structure in enzymes. In general, this book is well produced, has a useful index and is largely free of errors (although the positively charged azide functions on p. 51 should not go unchallenged). It is certainly a useful addition to the library of all research workers interested in applied enzymology and students of chemical engineering should find Chapters 2 and 5 particularly interesting. Those with specific interests in antibiotics or pollution control may be better served by more specialized texts.
EnzymeMicrob. Technol., 1979, vol. 1, January
R. A. G. Smith
Food Proteins - Improvement through Chemical and Enzymatic Modification Editors: Robert E. Feeney and John R. Whitaker American Chemical Society, Washington, DC, 1977, $23.00
This volume is the 160th in the valuable 'Advances in Chemistry Series' and consists of papers presented at a symposium in Mexico City in late 1975: the advances are therefore not the most recent. However, the editors (perhaps more aptly described as 'compilers' since there is little evidence in the elimination of duplicated information of the contributions having been edited) state that many of the new ideas presented appear to be 'blue sky' thinking which will challenge food scientists and technologists in the future. Challenges are always opportunities and this volume will prove stimulating to those scientists and technologists involved in the extension and development of the food protein industry. Since almost all proteins are either foodstuffs already or would be foodstuffs if made acceptable and/or safe for consumption this volume deals with almost all proteins. Chemical and enzymatic methods of modifying proteins are kept separate: Feeney contributes a review of the chemical methods available for modifying proteins in general and the effects such modifications have on their acceptability and properties. Gross deals specifically with the rare amino acid lysinoalanine, known from the microbial products nisin and subtilin and recently detected in foodstuffs subjected to alkaline conditions. Its physiological effects are unknown. Meyer and Williams review such work as has been done on the modification of soy protein products. Finally in this section Ryan deals concisely and readably with determinants of the functional properties of proteins and protein derivatives on foods. This more theoretical paper would have fitted more appropriately before the two shorter papers on specific topics. The greater part of the book is devoted to chapters on the enzymatic modification of proteins or protein sources. Whitaker introduces the subject in a wide-ranging paper which sets the scene for the following
Book Reviews chapters. Fujimaki, Arai and Yamashita review protein degradation and re-synthesis in the so-called 'plastein reaction' which allows the introduction of amino acids lacking in the original protein as well as converting undesirably textured or flavoured proteins into a bland, acceptable material. In a particularly valuable chapter, Richardson reviews work on functionality changes in proteins following enzymatic action. This introduces enzymic involvement in such processes as the tenderizing of meats both naturally and artifically, the changes occurring in dough during bread making and the alteration of milk proteins which occurs during
cheese preparation and maturation. The last two chapters deal with enzymatic methods of improving the acceptability of foodstuffs containing proteins by eliminating undesirable materials without altering the proteins themselves: Phaff's contribution is a thorough and detailed account of the structure of yeast cell walls and of the enzymes capable of degrading them and Liener deals with the removal of a mixed bag of toxic or undesirable materials ranging from cyanogens, through flatulenceproducing sugars in beans and lactose in milk to phytic acid in seed flours. The challenges presented in these chapters are severe: little is known of
the toxicity or otherwise of chemically-modifed proteins or of the plasteins, the plastein reaction will improve the acceptability of novel proteins but it will do nothing practical to improve the nutritional quality of dietary proteins until the rarer essential amino acids are available at economic prices and many of the enzymes mentioned are not commercially available in bulk, at least. Enzyme technology seems to have been applied to few of the problems presented, some of which should yield to ingenuity in enzyme or cell immobilization coupled with suitable reactor design. C. Bucke
Opportunities for collaboration in biochemical engineering The National Science Foundation (NSF) of the United States and the Korea Science and Engineering Foundation (KOSEF) of the Republic of Korea have selected biochemical engineering as a priority area for consideration and support under the United States-Republic of Korea Cooperative Science Program. A joint advisory committee, convened in August 1977, recommended cooperative research activities be developed in these areas: (1) Food Resources (use of cellulosic biomass for single cell protein production, single cell protein through photosynthesis, and improved methods of conservation and management of renewable food resources). (2) Pharmaceuticals and Fine Chemicals ( b i o t r a n s f o r m a t i o n microbial and enzymatic, fermentation technology problems, recovery and purification processes, cellular metabolites as potentially useful biologically active agents, and new techniques and developments for production of fine chemicals).
(3) Energy Resources Development and Bioconversion (biomass resources, methane production, carbohydrate production from biomass, utilization of carbohydrate from biomass, utilization of photosynthetic microorganisms, and systematic study of effective utilization, conservation and management of renewable and non-renewable energy resources). (4) Enzyme Technology (applications of enzyme technology in food, energy, chemical production, and environmental analysis and control; elements of enzyme technology in production of enzymes, isolation and purification processes, structure/ function relations, immobilization of enzymes and ceils, reactor design of enzymes and whole cells, and coenzyme regeneration). (5) Biological Waste Treatment for Pollution Abatement and Utilization of Byproducts (utilization of waste water and waste water sludges, utilization of feedlot waste, exploration of scale-up methods for waste water treatment, and regional waste water treatment systems).
(6) Microbial Strain D e v e l o p m e n t Physiology and Genetics (strain improvement for cellulose producing organisms, strain development for nucleosides/nucleotides production, genetics of the biochemical basis of nitrogen fixation by microorganisms, recombinant DNA research, and mechanisms of mutagenesis). NSF and KOSEF encourage US and Korean investigators whose work would be substantially advanced through collaboration and who may wish jointly to design and direct research in one of these areas to contact the programme managers for further information: Allen Holt Division of International Programs, National Science Foundation, Washington, D.C. 20550, USA Suhn Gun Kim Korea Science and Engineering Foundation, P.O. Box 124, Cheong Ryang 130, Seoul, Korea
Enzyme Microb. Technol., 1979, vol. 1, January
71