Showing papers in "Annual Review of Biochemistry in 1975"
TL;DR: This chapter discusses a study analyzing the three-dimensional structure of immunoglobulins, in which the periodicity of the crystal was used to reduce the background noise and reveal the molecular outline.
Abstract: Publisher Summary This chapter discusses a study analyzing the three-dimensional structure of immunoglobulins. Heavy atom derivatives were obtained. The compounds used were (1) p -chloromercuribenzene sulfonate (PCMBS), (2) mercuric cyanide Hg(CN) 2 , and (3) chloroplatinate ion, (PtCl 6 −− ). X-ray diffraction data were measured for the native crystals and each of the heavy atom derivatives to a Bragg spacing of 6 A. Electron micrographs were prepared of sections of the Dob crystals, cut perpendicular to the short c axis. The crystals were fixed with glutaraldehyde, washed, postfixed in osmium tetroxide, and embedded in Maraglas prior to sectioning. The sections were further stained with uranyl acetate and lead citrate solutions. The method of optical integration was applied in which the periodicity of the crystal was used to reduce the background noise and reveal the molecular outline. An electron density map was calculated with phases obtained from the heavy atom derivatives. The examination of the map showed that one pair of asymmetric units (containing one complete molecule) had density corresponding to three globular regions. One region lay on the twofold axis relating the two halves of the Dob molecule.
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TL;DR: This review will focus on recent studies in which amino acid exchange between various organs has been examined in a variety of physiologic and pathologic conditions in intact humans, with particular emphasis on the relationship of amino acid metabolism to gluconeogenesis, its interaction with glucoregulatory hormones, and its role in nitrogen exchange.
Abstract: Much of the interest in amino acid metabolism has centered on the intermediary steps involved in catabolism, the regulation of biosynthesis and transport, and genetic disorders resulting in abnormal urinary and/or plasma concentrations of amino acids. This review will focus on recent studies in which amino acid exchange between various organs has been examined in a variety of physiologic and pathologic conditions in intact humans. Particular emphasis, reflecting my own interest, will be focused on the relationship of amino acid metabolism to gluconeogenesis, its interaction with glucoregulatory hormones, and its role in nitrogen exchange. The technique used in determining tissue exchange of amino acids in many of the studies to be reviewed involves simultaneous sampling of arterial and venous blood across various organs and measuring blood flow. Where applicable, reference will be made to studies in experimental animals, although the data in humans form the overall basis of this review.
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TL;DR: The methylation of amino acids and proteins, themethylation of carbohydrates and polysaccharides, and present views on the role of A-Met as the sole biological methyl donor compound to substrates other than homocysteine are covered.
Abstract: Biological methylation is a broad subject that spans two principal areas of metabolism. First is a series of reactions leading to the biosynthesis of methionine (methylation of homocysteine) and then the multitude of reactions that utilize the methyl group of methionine after its activation to S-adenosylmethionine (A-Met). These, in fact, are not completely separate areas, and a link between them is provided by the highly specific requirement for A-Met in the terminal reaction of the methionine biosynthetic pathway (1-4). Moreover, A-Met plays a role as an inhibitor or a repressor of several enzymes that catalyze earlier steps in the methionine biosynthetic pathway (5-13). It would be impossible to cover this large and varied section of biochemistry in any depth in the space allotted, so I have chosen to limit very severely and quite arbitrarily the topics covered in this review. In this choice, I have been guided principally by my own biased curiosity, which has led me to examine in some detail areas relatively less familiar, not fully understood, or under rapid development. I will cover the methylation of amino acids and proteins, the methylation of carbohydrates and polysaccharides, and present views on the role of A-Met as the sole biological methyl donor compound to substrates other than homocysteine. Finally, I will list a number of methods that may be useful in the study of biological methylation. I am fully aware that this partial coverage will result in the complete omission of A nn u. R ev . B io ch em . 1 97 5. 44 :4 35 -4 51 . D ow nl oa de d fr om a rj ou rn al s. an nu al re vi ew s. or g
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TL;DR: The present review will restrict itself to the recent work on chemotaxis in Escherichia coli and Salmonella typhimurium.
Abstract: Bacterial chemotaxis, the movement of motile bacteria toward or away from chemicals, was discovered nearly a century ago by Engelmann (43) and Pfeffer (70, 71) The subject was actively studied for about fifty years, but then there were very few reports until quite recently For reviews of the literature up to about 1960, see Berg (23) , Weibull (90) and Ziegler (92) The present review will restrict itself to the recent work on chemotaxis in Escherichia coli and Salmonella typhimurium, some of which is also covered in Berg’s review (23)
406 citations
TL;DR: Biochemical Properties of Factor V11, Tissue Factor, and the Extrinsic System of Coayulation, as well as the Mechanism of Activation, are presented.
Abstract: CONTENTS INTRODUCTION. COAGULATION FACTORS AND THEIR NOMENCLATURE. MOLECULAR EVENTS IN BLOOD COAGULATION .. Biochemical Properties of Factor XII and Its Mechanism of Activation. Biochemical Properties oj Factor Xl and Its Mechanism oj Activation. Biochemical Properties oj Factor IX and Its Mechanism of Activation. Biochemical Properties oj Factor VIII and Its [nteraction with Factor I X" . Bioc:hemicul Properties of Fuclur X and Its Activation by Factor IXjj and Factor VIII. Biochemical Properties of Factor V and Its Interaction with Factor XIl • • • • • • • • • • • • • • Biochemical Properties qf Prothrombin and Its Activation by Factor Xa and Factor V ... Biochemical Properties rifFibrinogen and Its Interaction with Thrombin Biochemical Properties of Factor XI 11, Its Activation by Thrombin. and Its Interaction with Fibrin.. . .... .... . . Biochemical Properties of Factor V11, Tissue Factor, and the Extrinsic System of Coayulation.
334 citations
TL;DR: This chapter discusses the formation of Bile Acids, the use of Hydroxylation for Reduction, and the effects of diet and Vitamins and HORMONES on the synthesis of BILE Acids.
Abstract: INTRODUCTION 233 FORMATION OF BILE ACIDS 234 5fl Bile Acids 234 5~ Bile Acids 236 7c~ Hydroxylation of Cholesterol 237 12o~ Hydroxylation 238 26 Hydroxylation 238 Oxidation of 5fl-Chole~tane-3c~,7~t,12~,26-tetrol 239 METABOLISM OF BILE ACIDS 239 Conju,qation with Glycine and Taurine 240 Esterification with Sulfute and Glucuronic Acid 240 Reduction of Bile Acids in the Liver 240 Hydroxylation of Bile Acids in the Liver 241 Metabolism of Bile Acids in Extrahepatic Tissues 241 REGULATION OF BILE ACID FORMATION 242 EFFECT OF VITAMINS AND HORMONES 244 EFFECT OF DIET 244 CL1NICAL ASPECTS OF BILE ACID METABOLISM 245 Gallstone Disease 245 Liver Cirrhosi,s and Cholestasis 246 Hyperlipoproteinemias 247 NEW DEVELOPMENTS IN METHODOLOGY 248
293 citations
TL;DR: Energy-dependent quenchin 9 of ACMA fluorescence and the role of the ATPase Complex in Active Transport .
Abstract: INTRODUCTION TO TRANSPORT MECHANISM 524 Solute Modification (Group Translocation) 524 Carrier Modification 525 Indirect Coupling (Cotransport) 525 ENERGY COUPLING TO TRANSPORT IN CELLS AND MEMBRANE VESICLES ..... 526 Chemiosmosis 526 Energy Couplin 9 in Intact Cells 528 Energy from electron transport and ATP 528 Energy from a membrane potential 529 Energy Coupling in Membrane Vesicles 530 Orientation of membrane vesicles 531 Energy from electron transport and ATP 533 Energy from a membrane potential 535 Role of Energy in Facilitated Diffusion 536 Transport Systems That Can Use Only A TP 538 Conclusions: Sources of Energy for Active Transport 539 GENETIC ANALYSIS OF ENERGY COUPLING 539 The Mgz+.Ca2+-ATPase Complex 540 Uncoupled (unc) Mutants ; 541 Assignment of mutations to specific polypeptides 543 Energy-linked transhydrogenase 544 Energy-dependent quenchin 9 of ACMA fluorescence 545 Role of the ATPase Complex in Active Transport 546 Conclusions on unc Mutants 548 Mutations Affectin 9 the Electron Transport Chain 548
TL;DR: The Adair Scheme, the Sequential Models, the Two-State Model, and basic Observations provide evidence for nonequivalence in the context of collaborative building.
Abstract: INTRODUCTION 209 FORMULATIONS Ot v THE PROBLEM OF COOPERATIVE LIGAND B1NDING ...... 210 Earl), Models 210 The Adair Scheme 211 The Sequential Models 211 The Two-State Model 213 THE MINIMUM UNIT OF COOPERATIVITY 216 DEDUCTIONS EROM STRUCTURAL STUDIES 219 DETECTION OF THE T~-~R TRANSITION 221 EVIDENCE FOR NONEQUIVALENCE OF THE ~ AND /~ CHAINS 223 Basic Observations 223 Consequences ~f Chain Nonequivalence 225 GENERAL CONCLUSIONS AND’CURRENT ISSUES 226
TL;DR: These chemical modification experiments un ambiguously demonstrate the essential role of a histidine residue as a general base catalyst at the active site of fl-hydroxydecanoyl thioester dehydrase.
Abstract: ion from the IJ(-carbon (266). Although the dienic acids have high intrinsic reactivity, the enzyme is most potently inhibited by dienic acids of ten carbons. This correspondence to the enzyme specificity, also observed for inhibition by acetylenic derivatives, indicates that inhibition by the dienic acids proceeds via reversible binding followed by covalent bond formation (267). Comparison of the various Cl O dienic acid deriva tives shows that the effectiveness of inhibition decreases in the series thioester, oxygen ester, free acid, and amide. This pattern of reactivity would be expected if a Michael-type addition reaction (equation 28) was responsible for covalent bond H H 1 1 R C = C = C C X I I I N HN� R o H H I I R C = C C C X I � � N \) R 28. formation, since electrophilicity would be greatest for those derivatives where the resonance form, O-C = X, is least important. Although the precise structure of the histidine adduct has not been determined, model studies have demonstrated that the derivative with the /3-y double bond (28-1) is more likely than the 1J(-/3 isomer (267). It is not yet known which nitrogen in the imidazole nucleus of histidine serves as the nucleophile. However, these chemical modification experiments un ambiguously demonstrate the essential role of a histidine residue as a general base catalyst at the active site of fl-hydroxydecanoyl thioester dehydrase.
TL;DR: The role of proteolytic cleavage in the assembly of Bacteriophage T4 was discussed in this paper, and the role of the host cell was discussed as well.
Abstract: INTRODUCTION. 775 PROCESSING OF PICORNA VIR US PROTEINS. . 776 Formation of Primary Translation Product(s) . 777 Secondary Cleavages. 778 Proteolytic Cleavage in Picornavirus Assembly. 780 Enzymic Mechanisms. 781 POLYPEPTIDE CLEAVAGE IN VARIOUS ANIMAL VIRUSES. 782 ROLE OF PROTEIN CLEAVAGE IN THE MORPHOGENESIS OF COMPLEX BACTERIOPHAGES. 784 Cleavage of Head Proteins During the Assembly of Bacteriophage T4..... .. .. .. .. ... 784 Maturation of the head. . 784 Post-translational cleavage events. 786 Mechanisms of the cleavage reaction. 788 Role of the host cell. 789 Cleavage of Head and Tail Proteins in Some Other Large DNA-Containin" Bacteriophages. 790 Bacteriophage T 5 . 790 Bacteriophage P2 . 791 Bacteriophage ). . . . 792 CONCLUDING REMARKS. . . . . . . . . . . . . . . 793
TL;DR: The biolumineseent flash and the requirements for blue light emission are described, and the Hydrozoans and Ctenophores are studied.
Abstract: INTRODUCTION 255 COELENTERATE BIOLUMINESCENCE 256 The Anthozoans 256 Requirements for blue light emission 257 Requirements fi~r green light emission 259 Control of the biolumineseent flash 260 The Hydrozoans and Ctenophores 261 BACTERIAL BIOLUMINESCENCE 263 The Chemical Reaction 264 The Emitting Chromophore 266 FIREFLY BIOLUMINESCENCE 267 PHOLAD BIOLUMINESCENCE AND THE PEROXIDE SYSTEMS 268
TL;DR: The review is directed at describing and evaluating some of the data and hypotheses published since the last comprehensive review in 1970 at the photochemical processes in which a weak reductant and a strong oxidant are formed.
Abstract: This review is limited to information pertaining to Photosynthesis II in the photochemical processes in which a weak reductant and a strong oxidant are formed. The strong oxidant indirectly oxidizes H/sub 2/O. Artificial donor and acceptor reactions and the effects of inhibitors are only briefly mentioned. The results of the kinetic experiments related to the oxygen evolution system are discussed in the first section of the review. Results related to the identity of the components involved in the overall process are discussed. The review is directed at describing and evaluating some of the data and hypotheses published since the last comprehensive review in 1970. 216 references. (BLM)