← Retour

Enzyme Engineering

par: Samira LAGHA-BENAMROUCHE
Disponible
Pages 125
Dimensions 16*23,5
Publication 2025-09-24
Éditeur —
Papier : 950.00 DA Numérique: 475.00 DA

Living organisms are the site of countless biochemical reactions. These reactions take place under mild conditions thanks to the presence of biocatalysts, called enzymes. These molecules are omnipresent in the life of the cell. They are essential to cellular life; without them, none of the metabolic reactions would be possible. Enzymes are biological catalysts of protein nature. They exhibit remarkable specificity for particular chemical reactions in the metabolism of the organisms that produce them. Like all catalysts, enzymes act at very low concentrations, speeding up reactions without altering the outcome or thermodynamic equilibrium. At the end of the reaction, the enzyme’s structure remains unchanged and can catalyze subsequent cycles. Historically, humankind has used biotransformations empirically for millennia: sugar fermentation to ethanol for alcoholic beverages, ethanol oxidation to vinegar, and milk curdling by lactose fermentation. In these processes, enzyme catalytic activity drives the chemical transformations. The first practical application of an acellular enzyme was probably in cheese- making using rennet extracted from calf stomach to coagulate milk proteins. Today, enzymes have numerous applications: agri-food (human and animal nutrition), industrial (leather, paper, textiles, and detergents), medical and pharmaceutical sectors. Their utility in catalyzing reactions of industrial interest offers several advantages over conventional organic-chemical and microbiological processes: Simplified equipment and operations, possibly in sterile conditions after filtrating enzymatic solutions Catalytic specificity; High reaction rates and the potential for continuous, multi-step processes. The main drawbacks of enzymes are their instability and high cost. Advances in microbial fermentation, affinity chromatography purification, and enzyme immobilization have led to the emergence of enzyme engineering. Enzyme engineering is a branch of bioprocess engineering that involves the exploitation of enzymes through the identification of their specificities, the conditions of their purification, their modification in order to improve their properties and the optimal conditions of enzymatic catalysis and finally large-scale production for applied purposes. The use of enzymes in various industrial fields is of great interest and explains the efforts made in recent years by the scientific community in this direction. However, enzymes remain entities that are part of the living domain and their use requires taking certain precautions, in particular to preserve their catalytic properties. In addition, each enzyme has particularities; there is no universal solution applicable to this entire class of proteins. The course is divided into 4 chapters. The first chapter provides general notions on enzymes (structure, enzyme specificity, enzyme catalysis, classification and nomenclature). The second chapter deals with Michaelian enzyme kinetics with a substrate. The third chapter is devoted to modulators of the enzymatic reaction and the effect of reversible inhibitors on the enzymatic reaction. The last two chapters are devoted to industrial enzymes (sources, extraction, purification and immobilization) and their applications in different fields (agri-food, industrial (leather, paper, textile) and in molecular biology

Afficher la table des matières
Foreword 04
Introduction
Chapter 1: General Notions 13
1. Definition 14
2. Cofactor and coenzyme 14
3. Structure of the enzyme
4.1. Reaction specificity 17
4. Enzymatic specificity 17
4.2. Substrate specificity 17
5. Classification and nomenclature of enzymes
6. Enzymatic catalysis (Activation energy and transition state)
EXERCISES 25
SOLUTIONS 28
Chapter 2: Michaelian Enzyme Kinetics 33
1. Concept of initial velocity 34
1.1. Influence of enzyme concentration on speed
1.2. Influence of substrate concentration on speed
2. Michaelis Menten equation and graphical representation
(Lineweaver-Burk and Eadie-Hoftsee) 36
SOLUTIONS 45
3. Meaning of Maximum Speed and Michaelis Constancy
4. Enzymatic units and specific activity
EXERCISES
Chapter 3: Effectors of the enzymatic reaction 53
1. Influence of physicochemical parameters
1.1. Effect of temperature 54
1.2. pH effect 55
1.3. Effect of ionic strength
1.4. Divalent metals and cations
2. Proteolysis 59
3. Inhibitors 59
3.1. Competitive inhibition 60
3.2. Non-competitive inhibition 62
3.3. Uncompetitive inhibition 66
EXERCISES 69
SOLUTIONS 72
Chapter 4: Industrial enzymes 77
1. Preparation of enzymes 78
1.1. Sources 78
1.1.1. Plant cells 78
1.1.2. Animal cells 78
1.1.3. Microbial cells 79
2. Process of obtaining 81
2.1. Extraction 82
2.1.1. Processes used for plant and animal tissues
2.1.2. Processes applied to microbial cells
2.1.2.1. Solid-state fermentation
3. Parameters influencing FMS 85
3.1. The support
3.2. Temperature 85
3.3. Relative humidity and water activity
3.4. Ventilation 87
3.5. pH 87
4. The different types of industrial reactors
4.5. Fermentation in liquid medium 86
4.1. Tray bioreactors 88
4.2. Packed bed bioreactors 88
4.3. Rotating drum bioreactors 89
4.4. Fluidized bed bioreactors 89
5. Types of fermentation 90
5.1. Discontinuous culture (batch) 90
5.2. Fed batch culture 90
5.3. Continuous culture 91
6. Types of reactors 91
6.1. Suspended biomass bioreactor (homogeneous reactor)
6.2.1. Immobilized biomass bioreactor (heterogeneous reactor)
6.2.2. Splitting 93
6.2.2.1. Fractionation by salts or salting out (most widely used
process) 93
6.2.2.2. Isoelectric precipitation 94
6.2.2.3. Coagulation by temperature
6.2.2.4. Precipitation by organic solvents (especially alcohols
6.2.3. Purification
6.2.3.1. Size exclusion chromatography (gel filtration, permeation
or diffusion)
6.2.3.2. Ion exchange chromatography 96
6.3.Immobilized enzymes and their benefits
6.3.1. Methods of immobilizing enzymes 6.3.1.1. Physical adsorption 98
6.3.1.2. Encapsulation (inclusion in a gel)
6.3.1.3. Covalent grafting 101
6.3.2. Properties of immobilized enzymes
6.4.Areas of application of enzymes
6.4.1.Application in the food industry 95
6.2.3.3. Affinity chromatography 97
6.4.1.1. Use in breadmaking
6.4.1.2. Use in the preparation of beverages
6.4.1.2.1. Enzymatic clarification of fruit juices 6.4.1.2.2. Brewery 107
6.4.1.3. Use in the processing of fats and refining of vegetable oils
6.4.1.3.1. Lipolysis 109
6.4.1.3.2. Refining of edible oils
6.4.1.4. Use in dairy products
6.4.1.5. Use in meat products
6.4.1.6. Enzymes and hygienic quality of food
6.4.2.Application in the field of molecular biology
6.4.3. Industrial applications
6.4.3.1.Paper industry 114
6.4.3.2. Detergent industry 115
6.4.3.3.Textile desizing 116
6.4.3.4.Leather industry 116
EXERCISES 117
SOLUTIONS 119
BIBLIOGRAPHY
Acheter

Livres dans la même catégorie

Avis des lecteurs

Aucun avis pour le moment.