Doelle Bacterial Metabolism

2. Auflage 2014
ISBN: 978-1-4832-7237-5
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 752 Seiten

Bacterial Metabolism, Second Edition describes microbial systematics and microbial chemistry and focuses on catabolic events. This book deals with the progress made in bacterial metabolism that includes data on regulatory mechanisms; comparison of bacterial growth kinetics with enzyme kinetics; aerobic amino acid catabolism; and the glucose transport mechanism. This text also emphasizes the development of photosynthetic phosphorylation in the different bacterial families. This book explains anaerobic respiration and carbohydrate metabolism-glucose, fructose, lactose, mannose, allose, and sorbitol. This text then describes aerobic respiration including the 'Nitroso' and 'Nitro' groups of genera, and the Knallgas bacteria, which use the reaction between molecular hydrogen and molecular oxygen as their source of energy. This book also explains the microbial transformation of iron as caused by either specific organisms (e.g. Ferrobacillus ferrooxidans) or nonspecific organisms. This selection also explains the process of fermentation by Enterobacteriaceae, lactic acid bacteria, and proteolytic clostridia. This text can be valuable for microchemists, microbiologists, students, and academicians whose disciplines are in biological chemistry and cellular biology.

Autoren/Hrsg.

Doelle, H. W.

Inhaltsverzeichnis

1;Front Cover;1
2;Bacterial Metabolism;4
3;Copyright Page;5
4;Table of Contents;6
5;Preface;10
6;Preface to the First Edition;12
7;Chapter 1. Thermodynamics of Biological Reactions;16
7.1;Concepts of Thermodynamics;16
7.2;Free Energy;22
7.3;References;50
7.4;Supplementary Readings;51
7.5;Questions;51
8;Chapter 2. Enzymes, Coenzymes, and Bacterial Growth Kinetics;53
8.1;Enzymes;53
8.2;Coenzymes;60
8.3;Bacterial Growth Kinetics;81
8.4;References;92
8.5;Supplementary Readings;97
8.6;Questions;97
9;Chapter 3. Photosynthesis and Photometabolism;99
9.1;Terminology in Bacterial Metabolism;99
9.2;Photosynthesis;102
9.3;Photometabolism;131
9.4;Photochemical Nitrogen Fixation;149
9.5;The Electron Acceptor in Purple Bacteria;150
9.6;Evolution of Photosynthesis;152
9.7;References;152
9.8;Supplementary Readings;170
9.9;Questions;170
10;Chapter 4. Anaerobic Respiration;172
10.1;Sulfur Compounds as Electron Acceptors;173
10.2;Nitrate as Electron Acceptor;186
10.3;Carbon Dioxide as Electron Acceptor;204
10.4;References;208
10.5;Supplementary Readings;221
10.6;Questions;222
11;Chapter 5. Carbohydrate Metabolism;223
11.1;Glucose Metabolism;223
11.2;Fructose Metabolism;274
11.3;Lactose Metabolism;275
11.4;Mannose Metabolism;276
11.5;Allose Metabolism;278
11.6;Gluconate Metabolism;279
11.7;Mannitol Metabolism;282
11.8;Sorbitol Metabolism;284
11.9;Inositol Metabolism;285
11.10;Hexuronic Acid Metabolism;288
11.11;Peritose and Pentitol Metabolism;289
11.12;Glycerol Metabolism;296
11.13;Polyol Metabolism of Acetic Acid Bacteria;298
11.14;Glycol Oxidation;299
11.15;2,3-Butanediol Metabolism;303
11.16;References;305
11.17;Questions;326
12;Chapter 6. Aerobic Respiration—Chemolithotrophic Bacteria;327
12.1;The "Nitroso" Group of Genera;328
12.2;The "Nitro" Group of Genera;334
12.3;Hydrogenomonas or Knallgas Bacteria;341
12.4;The Iron-Oxidizing Bacteria;348
12.5;The Sulfur-Oxidizing Bacteria;354
12.6;Autotrophy and Heterotrophy;369
12.7;References;380
12.8;Questions;393
13;Chapter 7. Aerobic Respiration—Chemoorganotrophic Bacteria;395
13.1;Tricarboxylic Acid (TCA) Cycle;395
13.2;Electron Transport in Aerobic Microorganisms;409
13.3;Carboxylic Acid Metabolism;417
13.4;Regulatory Mechanisms of Carboxylic Acid Metabolism;437
13.5;Ethanol Metabolism;449
13.6;Methane Oxidation;450
13.7;Amino Acid Metabolism;457
13.8;References;481
13.9;Questions;503
14;Chapter 8. Aerobic Respiration—Hydrocarbon Metabolism;505
14.1;Oxidation of Alkanes and Alkenes;507
14.2;Oxidation of Aromatic Hydrocarbons;514
14.3;Metabolism of Halogenated Aromatic Hydrocarbons;533
14.4;Regulation of the Aromatic Hydrocarbon Metabolism;536
14.5;Metabolism of Phenoxyalkyl Carboxylic Acids;540
14.6;Metabolism of Riboflavin;548
14.7;Metabolism of Vitamin B6 (Pyridoxine);548
14.8;Metabolism of Steroids;551
14.9;Metabolism of Aromatic Polycyclic Hydrocarbons;552
14.10;Metabolism of p-Toluene Sulfonate;553
14.11;Metabolism of Coumarin;554
14.12;Metabolism of Pipecolate;555
14.13;Metabolism of 2-Furoic Acid;556
14.14;Oxygenases;557
14.15;References;558
14.16;Questions;572
15;Chapter 9. Fermentation;574
15.1;Introduction;574
15.2;Carbon, Energy, and Balance;578
15.3;Fermentation of Propionic Acid Bacteria;580
15.4;Fermentation of Saccharolytic Clostridia;589
15.5;Fermentation of Enterobacteriaceae;606
15.6;Regulation of Carbohydrate Metabolism in Facultative Anaerobic Bacteria (Pasteur and Crabtree Effects);624
15.7;Fermentation of Lactic Acid Bacteria;637
15.8;Fermentation of Proteolytic Clostridia;661
15.9;References;682
15.10;Questions;706
16;Subject Index;708
17;Microorganism Index;746

Leseproben

2 Enzymes, Coenzymes, and Bacterial Growth Kinetics
Publisher Summary
This chapter provides an overview of enzymes, coenzymes, and bacterial growth kinetics. Enzymes are true catalysts because they do not influence the point of equilibrium of the reaction they catalyze, nor are they used up during catalysis. Like other catalysts, enzymes lower the activation energy of the reaction they catalyze to obtain an equilibrium state of the reaction. It is impossible for the catalysis to overshoot this equilibrium state. Every enzymatically catalyzed reaction keeps on reacting until the equilibrium state is obtained. Enzymes consist of a protein component and a prosthetic group. Enzymes are not only chemically specific; they are also sterically specific when they act on substances containing asymmetric centers. The substrate may contain an asymmetric carbon atom, in which case it is usually found that the enzyme acts on only one of the optical isomers. To function, many enzymes require certain organic substances as cofactors. The cofactors, or coenzymes, generally act as acceptors or donors of groups of atoms that are removed from or contributed to the substrate. The most striking feature of these coenzymes is that the majority is either actual nucleotides or has some structural analogy with nucleotides. Enzymes
Catalytic Function
A high, negative value of ?F indicates that a chemical reaction is likely to proceed spontaneously and that the products will greatly exceed the reactants at equilibrium (see Table 2.1). However, it does not guarantee that the reaction will proceed with measurable speed. There exists a kind of energy barrier that must be overcome before the reaction can proceed. The important quantity is the free energy of activation. TABLE 2.1 Redox Potentials at pH 7.0 (E0’) for Some Biochemical Redox Systems       -0.47 Acetaldehyde/acetate       -0.42 H2/2 H+   -0.32 NADH + H+/NAD+           -0.20 Ethanol/acetaldehyde   -0.185 Riboflavin–P · H2/riboflavin –P     -11.5     -0.18 Lactate/pyruvate   -0.06 Flavoproteins       -0.05 Phyllohydroquinone/phylloquinone       -0.04 Cytochrome b           0.0 Succinate/fumarate -15.5     +0.01 Methylene Blue/leukodye       +0.20 Ascorbate/dehydro-ascorbate (pH 3.3)   +0.26 Cytochrome c       +0.29 Cytochrome a     -25.0     +0.81 ½O2/O2- Reactions that fail to proceed notwithstanding a high negative value of ?F can often be persuaded to do so in the presence of a catalyst. From the point of view of thermodynamics, a catalyst is something that lowers the free energy of activation. From the physical point of view, what probably happens is that the reactant combines temporarily with the catalyst. As a result, the energy of the reactant molecule is redistributed so that certain bonds become more liable to rupture by thermal agitation. Enzymes are true catalysts because they do not influence the point of equilibrium of the reaction they catalyze, nor are they used up during catalysis. Like other catalysts, enzymes lower the activation energy of the reaction they catalyze in order to obtain an equilibrium state of the reaction. It is impossible for the catalysis to overshoot this equilibrium state. Every enzymatically catalyzed reaction keeps on reacting until the equilibrium state is obtained. This is one of the basic laws of enzymology. The only possibility for a reaction to continue beyond equilibrium occurs in coupled reactions, where the product of the first reaction is immediately catalyzed to a further product with the help of a different enzyme. Therefore, an organism will never be close to a chemical equilibrium stage, as a system in equilibrium cannot perform any work. This continuous aim toward an equilibrium stage is quite often referred to as the “steady state,” wherein substrates must be continuously fed into a stationary system and the products of the reaction be taken out. As the organisms represent an open system, the steady state forms stationary concentrations that are different from the thermodynamically ruled chemical equilibriums. This is the main reason the reactions keep working toward the equilibrium state. The organism always gets its energy from these reactions. All the enzymes the chemical compositions of which have been investigated are proteins. The methods that are used to separate and purify enzymes are the same as those used to separate and purify proteins. Enzymes are susceptible to influences and agents that are known to affect proteins. The molecules have a limited life within a cell, new enzymes being continually produced to replace the old. With exceptions, they are rapidly denatured, and their catalytic properties destroyed, at temperatures of 50°C and over and by the ions of heavy metals. Their catalytic activities are notably affected by pH. Enzymes differ in several respects from inorganic catalysts. Enzymes are more efficient than such inorganic catalysts as platinum, show greater specificity, and are less stable. Enzymes consist of a protein component and a “prosthetic group.” The latter may be removed reversibly, and in such cases the protein part is called “apoenzyme” and the prosthetic group “coenzyme” (43). The protein component determines the substrate specificity, i.e., it decides which one of the substrates is to be converted. On many occasions it also determines the direction of the reaction, i.e., it determines to which of the many possible reactions the substrate molecule will go. This role of the apoenzyme is particularly obvious whenever the same coenzyme is attached to different apoenzymes, with different reaction products as results. One and the same coenzyme can therefore catalyze different reactions, depending on the apoenzyme (43). Much effort has been devoted to the study of enzymatic action (34). When an enzyme catalyzes a specific reaction, it first combines transiently with the substrate, the name given to the substance on which the enzyme acts, to form the enzyme–substrate complex. In this complex, there is a “lock-and-key” fit of the substrate molecule to a “patch” on the surface of the very large enzyme molecule (51). This patch is called the “active site,” and because of the specific geometrical relationship of the chemical groups that combine with the substrate, it can only accept molecules having a complementary fit. During the formation of the enzyme–substrate complex, the enzyme molecule is twisted somewhat, which places some strain on the geometry of the substrate molecule. This renders it susceptible to attack by H+ or OH- ions or by specific functional groups of the enzyme. In this manner the substrate molecule is converted to its products, which now diffuse away from the active site. The enzyme molecule returns to its native shape, combines with a second substrate molecule, and repeats the cycle. Most enzymes can be inhibited by specific poisons, which may be structurally related to their normal substrate. Such inhibitors are very useful in analyzing enzyme-catalyzed reactions in cells and tissues. When enzymes act in a sequence, so that the product of one enzyme becomes the substrate for the next, and so on, we have a multienzyme system and the chains of reactions are known as “metabolic pathways.” Enzymes are not only chemically specific, they are also sterically specific when they act on substances containing asymmetric centers. The substrate may contain an asymmetric carbon atom, in which case it is usually found that the enzyme acts on only one of the optical isomers. Specificity of this type appears usually to be absolute. A good example is glyceraldehyde-3-phosphate dehydrogenase, which reacts only with the d isomer of dl-glyceraldehyde 3-phosphate. Substrate concentration is one of the most important of the factors that determine the velocity of...