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Enzymes, Second Edition provides information pertinent to the developments in the field of enzymology. This book presents the properties of enzymes as chemical catalysts or simply as chemical substances.
Organized into 13 chapters, this edition begins with an overview of the range of action or specificity of enzymes. This text then discusses the special techniques employed in the isolation of enzymes and explores the considerable progress in the study of the properties and functions of enzymes. Other chapters consider the mechanism of enzyme catalysis by more direct methods, including the use of isotopes. This book discusses as well the mechanism of the biosynthesis of enzymes and the means by which their chemical structure is determined by the genetic material of the chromosomes. The final chapter deals with the essential aspects of the enzymatic system linking energy-producing processes with energy-utilizing processes.
This book is a valuable resource for biochemists, physical chemists, and research workers.
Contenu
Preface
I. Introduction
II. Enzyme Techniques
Measurement of Velocity
Classes of Methods
Some Practical Points
The General Handling of Enzymes
The Study of an Enzyme
The Specific and Molecular Activities
Enzyme Affinities
Methods of Quantitatively Following Enzyme Reactions
(a) Spectrophotometric Methods
(b) Manometric Methods
(c) The Thunberg Method
(d) Electrode Methods
(e) Polarimetric Methods
(f) Chromatographic Methods
(g) Chemical Estimations
III. Enzyme Isolation
Importance of Enzyme Purification
Methods of Purification
(a) Test
(b) General Procedure
(c) Source of Enzyme
(d) Extraction
Fractionation Methods
(a) Fractional Precipitation by Change of pH
(b) Fractional Denaturation by Heating
(c) Fractional Precipitation with Organic Solvents
(d) Fractional Precipitation by Salts
(e) Fractional Adsorption
(f) Column Chromatography
(g) Crystallization
(h) Sequence of Fractionation Methods
(i) Other Methods
Criteria of Purity of Enzymes
Pitfalls in Working with Pure Enzymes
IV. Enzyme Kinetics
The Importance of Enzyme Kinetics
Factors Influencing Enzyme Reaction Velocity
(A) Effect of Enzyme Concentration
(B) Effect of Substrate Concentration
(c) Effect of pH
(D) Effect of Temperature
V. Enzyme Classification
Enzyme Commission's Numbering System
Rules for Systematic and Trivial Nomenclatures
(i) General Rules
(ii) Rules for Particular Classes of Enzymes
Enzyme Reactions
Oxidoreductases
Transferases
Hydrolases
Lyases
Isomerases
Ligases
VI. Enzyme Specificity
The Investigation of Enzyme Specificity
General Observations on Specificity
Stereospecificity of Enzymes
Illustrative Examples of Enzyme Specificity
Dehydrogenases
Glucose Oxidase
Methyltransferases
Transketolase and Transaldolase
Glycosyltransferases
Phosphotransferases
Esterases
Phosphatases
Glycosidases
Peptidases
Lyases
Aldose Mutarotase
Enzymes with Substrates Containing Hydrocarbon Chains
General Conclusions
VII. Enzyme Mechanisms
Mechanism of Hydrogen-Transfer Reactions
Alcohol Dehydrogenase
Glyceraldehydephosphate Dehydrogenase
Lipoamide Dehydrogenase
Mechanism of Transferring (or Hydrolysing) Enzymes
(a) Identification of the Bond Affected
(b) Isotope Exchange Methods
(c) The Optical Inversion Method
(d) Inferences from Competition and Other Effects
(e) Identification of Intermediate Complexes
Mechanism of Lyases
Fumarate Hydratase
Aspartate Ammonia-Lyase
Mechanism of Isomerases
Epimerases
Methylmalonyl-CoA Racemase
Cis-trans Isomerases
Ketol-Isomerases
-Isomerases
Methylmalonyl-CoA Mutase
Mechanism of Ligases
Triple-Transfer Mechanism
Ternary Complex Mechanisms
Mechanism of Metalloenzymes
Metal-Activated Peptidases
Zinc-Containing Dehydrogenases
Metalloflavoproteins
Haemoprotein Enzymes
VIII. Enzyme Inhibitors
Types of Inhibitors
Competitive Inhibitors
Non-Competitive Inhibitors
'Mixed-Type' Inhibitors
Graphical Presentation of Inhibitor Effects
Determination of Inhibitor Constants
Other Types of Inhibitors
Inhibitors with Very High Affinities
Effect of pH on Inhibition
Some Important Inhibitors
Poisons of Heavy Metals
Reagents for Thiol Groups
Heavy Metals
Irreversible Organophosphorus Inhibitors
Inhibitors of Respiration and Phosphorylation
Competitive Inhibitors
Antienzymes
IX. Enzyme Cofactors
Specific Coenzymes
Hydrogen Carriers
Lipoate
Glutathione
Ascorbate
Quinones
Cytochromes
Cytochrome Oxidase
Other Hydrogen Carriers
Amino-Group Carriers
2-Oxoglutarate
Phosphate Carriers
Nucleoside 5'-Diphosphates
Mixed Phosphate and Glycosyl Transfers
Acyl-Group Carriers
Coenzyme A
Carriers of One-Carbon Groups
Tetrahydrofolate
Adenosylhomocysteine
Cobamide Coenzymes
Prosthetic Groups as Carriers
Flavin Groups
Pyridoxal Phosphate
Thiamine Pyrophosphate
Biotin
Other Coenzymes
Phosphomutase Coenzymes
Glutathione as a Specific Coenzyme
Relationship Between Coenzymes and Vitamins
Significance of 'Nucleotide' Structure in Coenzymes
Enzyme Activators
Simple Electrolytes
Lipophilic Ions
Polynucleotide Templates
The Distinction Between Prosthetic Group, Coenzyme and Substrate
X. Enzyme Structure
Molecular Weight
Protein Structure
Number of Peptide Chains
Aminoacid Composition
Aminoacid Sequence
Structure and Configuration of the Enzyme Protein
The Chemistry of the Active Centre
Number of Active Centres Per Molecule
Chemical Nature of the Active Centre
XI. Enzyme Formation
The Biosynthesis of Enzymes
Biosynthesis of Proteins
Induction and Repression
Enzyme Formation from Precursors
The Activation of Pepsinogen
The Activation of Prorennin
The Activation of Trypsinogen
The Activation of Chymotrypsinogen
The Activation of Procarboxypeptidases
Activation of the Pancreatic Complex
Other Precursors and their Activation
XII. Enzyme Systems
The Biological Importance of Systems of Enzymes
Linking of Enzymes
Coenzyme-Linked Dehydrogenase Systems
Distributive Function of Transferring Enzymes
Transit Time
Structurally Organized Enzyme Systems
Some Properties of Multi-Enzyme Systems
Comments on Tables
Tables of Enzyme Systems
The Glycolysis System
The Citric Cycle
The Glyoxylate Cycle in Plants and Micro-Organisms
Fatty Acid Breakdown and Synthesis
The Glucose 6-Phosphate Oxidation System
A Hydrogen-Transport System in Plants
Phenylalanine Oxidation System
The Glyoxalase System
The Galactose-Inverting System
Methionine Metabolism
Glycogen Synthesis
Interconversion of Pentoses in Lactobacillus
Synthesis of Isoprenoid Compounds
Urea Formation in Liver
Phosphatide Synthesis
Synthesis and Breakdown of NAD and NADP
Coenzyme a Synthesis
Nucleotide Synthesis
Formation of Sucrose in Photosynthesis
XIII. Enzyme Biology
Enzymes as the Basis of Life
Enzymes and Cell-Structu…