Structure and Functions of Contractile Proteins (eBook)

Revisions, Additions, and a Foreword to the English-Language Edition Prepared by the Author

Boris F. Poglazov (Autor)

eBook Download: PDF | EPUB

2014 | 1. Auflage
340 Seiten
Elsevier Science (Verlag)
978-1-4832-7086-9 (ISBN)

Infos

Structure and Functions of Contractile Proteins focuses on the analysis of problems on the structure and functions of contractile proteins in which substantial progress has been achieved. The book first offers information on the protein constitution of myofibrils and myosin, including adenosinetriphosphatase activity, reaction with actin, and myosin molecule. The text also ponders on the polymerization of actin, tropomyosin, and the theory of contraction. Discussions focus on model experiments and molecular basis of contraction; structural interrelations of muscle proteins; features of the process of polymerization of actin; and size of the actin molecule. The text elaborates on the contractile proteins of the elementary motor structures of cells, as well as the chemical composition and physicochemical and enzymic properties of flagella and cilia; achromatin apparatus and movement of chromosomes; and structure of the flagella and cilia. Motor apparatus of bacteriophage and features of the movement of protoplasm and the mechanism of permeability are also discussed. The manuscript is a reliable source of data for readers interested in the structure and functions of contractile proteins.

Inhalt

Front Cover 1
Structure and Functions of Contractile Proteins 4
Copyright Page 5
Table of Contents 14
Foreword 6
Foreword to the English Edition 8
Preface 10
List of Abbreviations 12
INTRODUCTION 16
CHAPTER 1. THE PROTEIN CONSTITUTION OF THE MYOFIBRILS 20
CHAPTER 2. MYOSIN 28
Adenosinetriphosphatase Activity 28
Reaction with Actin 51
The Myosin Molecule 57
CHAPTER 3. POLYMERIZATION OF ACTIN 72
Size of the Actin Molecule 73
Features of the Process of Polymerization of Actin 74
CHAPTER 4. TROPOMYOSIN 88
CHAPTER 5. THE THEORY OF CONTRACTION 94
Structural Interrelations of the Muscle Proteins 94
Model Experiments and the Molecular Basis of Contraction 114
CHAPTER 6. CONTRACTILE PROTEINS OF THE ELEMENTARY MOTOR STRUCTURES OF CELLS 128
Structure of Flagella and Cilia 129
Chemical Composition and Physicochemical and Enzymic Properties of Flagella and Cilia 136
Achromatin Apparatus and Movement of Chromosomes 154
CHAPTER 7. MOTOR APPARATUS OF BACTERIOPHAGE 174
Structural and Functional Properties of Head of Bacteriophage T2 175
Caudal Sheath of Bacteriophage T2 183
CHAPTER 8. SOME FEATURES OF THE MOVEMENT OF PROTOPLASM AND OF THE MECHANISM OF PERMEABILITY 250
Actomyosin-Like Proteins and Protoplasm Movement 251
Isolation of Actomyosin Proteins from Internal Organs and Tissues of Animals 272
Mechanism of Regulation of Phenomena of Permeability 279
CHAPTER 9. THE MECHANISM OF MOVEMENT IN PLANTS 290
SUMMARY 298
REFERENCES 300
INDEX 338

Textauszug

2

Myosin

Publisher Summary

This chapter focuses on the magnitude of the efforts that have been made to study the mechanism of the ATP-ase action of myosin. Even with the recent developments, the details of the mechanism of transfer and utilization of the energy of ATP hydrolysis have not yet been experimentally resolved. The chapter also discusses the properties of actomyosin in solutions with ionic strength of 0.3 and higher, that is, under conditions in which actomyosin is readily soluble. A decrease of the ionic strength of the solution results in the precipitation of actomyosin; the resultant solid gel possesses a number of characteristic properties and is extensively used as a contractile experimental model. Danilevskii’s investigations have shown that myosin possesses LBR. In 1934, it was confirmed by means of polarization-optical measurements that the anisotropism of muscle fibers is because of the presence of myosin. The presence of LBR is because of asymmetry of the molecules. In the case of muscles, whose main property is contraction and change in length and breadth of their structural elements, investigation of the optical properties is of particular importance.

ADENOSINETRIPHOSPHATASE ACTIVITY

The fact that animal tissues contain adenosinetriphosphatase (ATP-ase), which is capable of splitting off two phosphate residues from ATP, was first shown by Jacobsen in 1931, and Barrenscheen and Lang in 1932. Lohmann in 1935 then found that washed muscles were capable of splitting off one phosphate group and only the addition of Mg++ could fully restore its activity. It was accordingly concluded that muscle contained two enzymes which split off phosphorus from ATP. One of these enzymes, granular ATP-ase, investigated by Sakov (1941), Kielley and Meyerhof (1948), was a constituent of the sarcoplasm. The remaining ATP-ase activity was found in myosin (Engelhardt and Lyubimova, 1939; Lyubimova and Engelhardt, 1939). It was shown in a number of other studies (Engelhardt and Lyubimova, 1939; Singer and Barron, 1944; Singer and Meister, 1945; Engelhardt and Yarovaya, 1955; Bailey and Perry, 1947) that the ATP-ase activity is inseparable from myosin, is lost simultaneously with the appearance of signs of denaturation of myosin, and changes parallel with change in the content of SH groups and in the capacity of myosin to react with actin. Under optimal conditions 1 mole of myosin (molecular weight 500,000) splits about 50 moles of ATP per sec (Engelhardt, 1946; Szent-Györgyi, 1947). Although these figures show that myosin is less active than many enzymes, it is present in muscle in amounts considerably exceeding the content of other enzymes in any tissue. Because of these features some authors have doubted that myosin and ATP-ase are in fact identical. For instance, because myosin, when mixed with potato apyrase precipitates with it, Kalckar (1944) concluded that ATP-ase was an impurity in myosin. Price and Cori (1946) postulated that the ATP is cleaved by creatine kinase present in preparations of myosin, but subsequently abandoned this hypothesis as unsubstantiated. Polis and Meyerhof (1946) tried to separate ATP-ase from myosin by fractionation with lanthanum salts but were unable to obtain convincing results.

Thus, the findings of Price and Cori and Polis and Meyerhof support the opinion that myosin and ATP-ase are one and the same substance.

INFLUENCE OF PH

In their first study on myosin Engelhardt and Lyubimova (1939) found that myosin ATP-ase has a maximal activity at pH 9.0. Subsequent, more detailed study showed that besides a major peak at pH 9.0 there was another, smaller peak at pH 6.3 (Engelhardt and Lyubimova, 1942; Engelhardt, 1946) (Fig. 1). The presence of two peaks was attributed by the authors to different ionization of the enzyme and substrate at different pH, on the assumption that the formation of the enzyme-substrate complex between myosin and ATP was heteropolar.

FIG. 1 ATP-ase activity in relation to pH (Engelhardt, 1946). 1—Calcium salt of ATP; 2—in presence of 0.01 M MgCl2.

Mommaerts and Seraidarian (1947), who investigated the influence of various buffers and of the salt concentration, pointed out that a glycine buffer had a distinctly beneficial effect on the ATP-ase activity of myosin. Both this article and a later report (Mommaerts and Green, 1954) confirmed the presence of two peaks of myosin ATP-ase action. One peak lay in the region of pH 6.3–6.5 and the other at pH 9 and higher, the activity in the alkaline zone increasing proportionately to the increase of concentration of hydroxyl ions. According to these authors, the increase in activity was due to the participation of OH− instead of water in the cleavage of ATP. Stracher (1961) investigated the effect of strong alkalinization on the ATP-ase activity of myosin. He succeeded in clearly showing that inhibition of the enzymic reaction started at approximately pH 10; increase of pH from 10.1 to 10.3 resulted in loss of 90% of the myosin ATP-ase activity, apparently because of disturbance of the structure of the protein molecule.

The relation of ATP-ase activity to pH is altered by the reaction of myosin with actin. Biro and Szent-Györgyi (1949) found that the ATP-ase of myosin as part of actomyosin has only one peak of activity (at pH 6.62) instead of two.

EFFECT OF METAL IONS

Throughout the entire history of the study of muscle proteins the effects of metal ions have been frequently investigated. A number of metal ions play a significant role both in the manifestation of the enzymic action of myosin and in muscular contraction.

No ATP-ase activity could be found in solutions of myosin in the absence of salts (Mommaerts and Seraidarian, 1947). The addition of KCl in small amounts caused activation of ATP-ase. The optimal concentration of KCl was found to be 0.3 M, if the medium did not contain any Ca++. In the presence of 0.001 M CaCl2, activity was optimum at lower concentrations of KCl (0.1–0.05 M). High concentrations of KCl had an inhibitory effect.

In studying the action of ions on ATP-ase activity, special attention was given to the antagonistic action of Ca++ and Mg++. Lyubimova and Engelhardt (1939) and Lyubimova and Pevsner (1941) showed that the ATP-ase of myosin is activated by Ca++ but inhibited by Mg++. Activation by calcium could be observed both in the presence and in the absence of KCl (Mommaerts and Seraidarian, 1947). CaCl2 was most effective in a concentration of 0.04 M at physiologic values of pH and in a concentration of 0.001 M at pH 9.0 (Mommaerts and Green, 1954). The inhibitory action of MgCl2 was manifested after the ATP-ase activity of myosin had been stimulated by K+ or Ca++. If ATP-ase activated by calcium ions was treated with MgCl2 in amounts equivalent to the CaCl2 concentration a 90% decrease in the activity ensued (Mommaerts and Seraidarian, 1947).

Ca++ also has an activating effect on actomyosin, but Mg++ acts differently (Table 1). Low concentrations of KCl (0.01 M) or in its absence, Mg++ increase the ATP-ase activity of actomyosin, but higher concentrations of KCl (0.1 M) depress it (Banga, 1942; Nagai, Konishi, Yutasaka, Takahashi and Makinose, 1957).

TABLE 1

Effect of K+, Mg++ and Ca++ on ATP-ase activity of actomyosin (Banga, 1942)
Activity given in mg P split off in 5 min

1.4

0.003

0.037

0.074

0.055

0.074

2.8

0.006

0.078

0.104

0.100

0.120

4.2

0.019

0.104

0.162

0.140

0.134

5.6

0.038

0.134

0.168

0.162

0.180

The depression of activity in this case is due to the dissociating effect of high concentrations of KCl on the actomyosin complex. However, at low concentrations of KCl the action of the actinmyosin bonds is revealed. If CaCl2 and MgCl2 are added simultaneously, the ATP-ase activity of actomyosin is suppressed at any concentration of KCl. The dependence of the ATP-ase activity of isolated myofibrils on Ca++ and Mg++ was investigated by Perry and Chappell (Perry, 1951; Chappell and Perry, 1955; Perry and Chappell, 1957). It was shown that Ca++ and Mg++ have an activating effect. At pH 6.9 and 8.6, MgCl2 in a concentration of 0.001–0.002 M has an activating effect equal to that of CaCl2 in optimal concentrations. The influence of temperature in this case is interesting. Activation by calcium is identical at 0°C and at 20°C. Mg++ has a strong activating effect at 20°C, but little or none at 0°C. Analogous results were obtained by Hasselbach in 1952 in a study of the ATP-ase of isolated myosin.

In this situation the next logical step was to carry out experiments on the...

Produkt-Details

• Erscheint lt. Verlag: 28.6.2014
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Biologie ► Biochemie
• Themenwelt: Naturwissenschaften ► Biologie ► Genetik / Molekularbiologie
• Themenwelt: Naturwissenschaften ► Physik / Astronomie ► Angewandte Physik
• Themenwelt: Technik
• ISBN-10: 1-4832-7086-6 / 1483270866
• ISBN-13: 978-1-4832-7086-9 / 9781483270869