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Pascale Mentré
WATER IN THE CELL
A heterogeneous and dynamic interface of macromolecules
Paris: MASSON-DUNON, 1995
Though it represents more than 70% of the total weight, the aqueous
interface of the macromolecules in the cell consists only in a few
layers of water molecules. This results from the high surface/volume
ratio of the macromolecules and their overcrowding in the cell. Water
molecules are small electric dipoles. They organize in a heterogeneous
way at the contact of the macromolecule surfaces because these ones are
mosaics of ionic, polar and apolar domains. In fact, because the cell is
tremendously heterogeneous, any macromolecule, ion and, may be, water
molecule is in a unique situation. One main consequence is that the
application of the laws of the classical chemistry in the cell is
meaningless because these laws are based on the properties of the great
numbers.
There is another problem. The interfacial water differs from the
ordinary water by several physical properties, particularly a low
solving power, so that it is not a good medium for the diffusion of ions
and small molecules.
Therefore, how to explain the extraordinary efficiency of the cell
metabolism if the numbers of reacting molecules and the rates of
diffusion are too low? Authors proposed models in which physical
interactions between interfacial water, macromolecules and ions could
play a primordial role.
This book was conceived by a biologist for biologists, at their request.
The author, though she sometimes brings in physical and mathematical
concepts, does not aim to produce a theoretical analysis, which is
necessary if this were a biophysics text. Her purpose is just to present
a new and fascinating view of the cell, derived from the work of many
eminent biophysicists, which allowed us to relate in simple terms their
conclusions to our everyday experience.
Pascale Mentre, is a lecturer at the University Pierre et Marie Curie of
Paris, former pupil of Ecole Normale Superieure and agregee de Sciences
Naturelles. Currently, she teaches cell biology and computer science
applied to biology and works at the Institut de Biologie Physico-Chimique
on the problem of water in the biological matrices.
CONTENTS
Preface XIII
I. Review of classical notions
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Chapter 1. Properties of bulk water 3
1.1. Bulk water, an unusual liquid 3
1.2. Polarity of water and the hydrogen bond 4
1.3. Solvation 11
1.4. Protonic currents 15
1.5. Other consequences of the water molecule configuration 17
1.6. Conclusion 18
Chapter 2. Diffusion and osmosis 21
2.1. Principle of diffusion 21
2.2. Demonstration and quantitation of the osmotic pressure 23
2.3. Colligative character of the osmotic pressure 25
2.4. The semi-permeable membrane 29
2.5. The Watterson's theory: osmosis and the cooperativity of water
molecules 36
2.6. Is water dominated by extensivity or cooperativity? 38
Chapter 3. Colloids, gels and amphiphilic structures 41
3.1. Colloids 41
3.2. Gels 48
3.3. Amphiphilic structures 58
II. Interactions between water, macromolecules and
ions
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Chapter 4. The macromolecule hydration shell, "bound" and
"structured" water 65
4.1. Notion of hydration shell 65
4.2. Hydration of hydrophilic domains 67
4.3. Hydration of hydrophobic domains 72
4.4. The intramolecular water 77
4.5. Polemics about the hydration shell 78
Chapter 5. The quirks of the hydration shell 83
5.1. Ice-like character of water in the hydration shell 83
5.2. Unfreezable and non-sublimable character of structured water 86
5.3. Abnormally high specific heat of structured water 88
5.4. Specific-mass variations of structured water 89
5.5. Exclusion and partition of ions 91
5.6. Thermal "kinks" 97
5.7. The paradoxal effect 99
III. The exploitation of water's properties by
macromolecules
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Chapter 6. Water, and the shape of macromolecules 107
6.1. The configuration of the macromolecules and the hydration shell 108
6.2. The energy relations between water and macromolecules 113
6.3. Water and the molecular assemblies 116
6.4. The size of proteins and the vibratory state of water 126
6.5. Fluctuations of the macromolecule shape 129
Chapter 7. "Bound water", necessary, sufficient andS tamed? 133
7.1. The cooperative role of water in the macromolecule stability 133
7.2 Allostery, a cooperative phenomenon in which water is involved 136
7.3. Bound water is necessary for enzyme activity 140
7.4. Only a little part of bound water is required for enzyme activity
144
7.5. Water and the molecular recognition. The star activity 148
7.6. Sol ? gel transitions, ions and autoregulation 150
7.7. Sol ? gel transitions and cell pathology. The tamed water 152
IV. Water and the architecture of the cell matrices
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Chapter 8. Discussion of diffusion in the cell 159
8.1. Classical representation of the cell 159
8.2. Discussion of diffusion in the cell 168
Chapter 9. Is cell nearer from the solid state than the liquid
one? A cytochemical approach 185
9.1. Detection of the weakly gelified domains. Precipitation methods
coupled to microanalysis 186
9.2. Conservation of the ions-macromolecules-water equilibrium 189
9.3. Gelation and migration of macromolecules. An immunocytochemical
approach 195
9.4. Is cell liquid or quasi-solid? Freezing and vitrification 197
V. Metabolite transport in the cell
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Chapter 10. Transport in the cell 205
10.1. Diffusion limited to one or two dimensions 207
10.2. Transport of metabolites : compartmentation and channeling 208
10.3. Transduction of energy and apparent transport 218
Chapter 11. An alternative to the classical interpretation of ion
fluxes across membranes 235
11.1. Discussion of the membrane theory 236
11.2. Electrical phenomena at the macromolecular level 249
11.3. The phase theory 257
11.4. Conclusion : dogmas and theories 261
VI. Conclusion
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Chapter 12. Water, a heterogenous and dynamic interface of
macromolecules 267
12.1. Heterogeneity of water 267
12.2. Dynamism of the interactions between water and macromolecules 272
Annexe 277
Index 285
List of some articles
1.
Mentré
P.
and Debey P. An unexpected effect of an ouabain-sensitive ATPase
activity on the amount of antigen-antibody complex formed in situ.
Cellular and Molecular Biology 45(6): 781-791, 1999.
2. Mentré
P.
Organization and
properties of water in cell system. In: Itegrated Plant Systems.
H.Greppin et al., eds. University of Geneva, pp.3-22, 2000.
3. Mentré
P. An
introduction to "water in the cell": tamed hydra?
Cellular and Molecular Biology 47(5): 709-715,
2001.
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