Microcalorimetry of Macromolecules

Examining the physical basis of the structure of
macromolecules--proteins, nucleic acids, and their
complexes--using calorimetric techniques

Many scientists working in biology are unfamiliar with the
basics of thermodynamics and its role in determining molecular
structures. Yet measuring the heat of structural change a molecule
undergoes under various conditions yields information on the
energies involved and, thus, on the physical bases of the
considered structures. Microcalorimetry of Macromolecules
offers protein scientists unique access to this important
information.

Divided into thirteen chapters, the book introduces readers to
the basics of thermodynamics as it applies to calorimetry, the
evolution of the calorimetric technique, as well as how
calorimetric techniques are used in the thermodynamic studies of
macromolecules, detailing instruments for measuring the heat
effects of various processes. Also provided is general information
on the structure of biological macromolecules, proteins, and
nucleic acids, focusing on the key thermodynamic problems relating
to their structure. The book covers:

• The use of supersensitive calorimetric instruments, including
  micro and nano-calorimeters for measuring the heat of isothermal
  reactions (Isothermal Titration Nano-Calorimeter), the heat
  capacities over a broad temperature range (Scanning
  Nano-Calorimeter), and pressure effects (Pressure Perturbation
  Nano-Calorimeter)

• Two of the simplest but key structural elements: the alpha and
  polyproline helices and their complexes, the alpha-helical
  coiled-coil, and the pyroline coiled-coils

• Complicated macromolecular formations, including small globular
  proteins, multidomain proteins and their complexes, and nucleic
  acids

• Numerous examples of measuring the ground state of protein
  energetics, as well as changes seen when proteins interact

The book also reveals how intertwined structure and
thermodynamics are in terms of a macromolecule's organization,
mechanism of formation, the stabilization of its three-dimensional
structure, and ultimately, its function. The first book to describe
microcalorimetric technique in detail, enough for graduate students
and research scientists to successfully plumb the structural
mysteries of proteins and the double helix, Microcalorimetry of
Macromolecules is an essential introduction to using a
microcalorimeter in biological studies.

Auteur

PETER L. PRIVALOV is a Professor of Biology and Biophysics at the Johns Hopkins University since 1991. He received his PhD in physics from the University of Georgia, Tbilisi (former USSR), and his DrSc in biophysics from the Institute of Biophysics, Russian Academy of Sciences, Moscow. For many years, he headed the Laboratory of Thermodynamics at the Protein Research Institute of the Russian Academy of Sciences. He is the author of 230 scientific papers published in various international journals and periodicals.

Résumé

Examining the physical basis of the structure of macromoleculesproteins, nucleic acids, and their complexesusing calorimetric techniques

Many scientists working in biology are unfamiliar with the basics of thermodynamics and its role in determining molecular structures. Yet measuring the heat of structural change a molecule undergoes under various conditions yields information on the energies involved and, thus, on the physical bases of the considered structures. Microcalorimetry of Macromolecules offers protein scientists unique access to this important information.

Divided into thirteen chapters, the book introduces readers to the basics of thermodynamics as it applies to calorimetry, the evolution of the calorimetric technique, as well as how calorimetric techniques are used in the thermodynamic studies of macromolecules, detailing instruments for measuring the heat effects of various processes. Also provided is general information on the structure of biological macromolecules, proteins, and nucleic acids, focusing on the key thermodynamic problems relating to their structure. The book covers:

• The use of supersensitive calorimetric instruments, including micro and nano-calorimeters for measuring the heat of isothermal reactions (Isothermal Titration Nano-Calorimeter), the heat capacities over a broad temperature range (Scanning Nano-Calorimeter), and pressure effects (Pressure Perturbation Nano-Calorimeter)
• Two of the simplest but key structural elements: the and polyproline helices and their complexes, the -helical coiled-coil, and the pyroline coiled-coils
• Complicated macromolecular formations, including small globular proteins, multidomain proteins and their complexes, and nucleic acids
• Numerous examples of measuring the ground state of protein energetics, as well as changes seen when proteins interact
  The book also reveals how intertwined structure and thermodynamics are in terms of a macromolecule's organization, mechanism of formation, the stabilization of its three-dimensional structure, and ultimately, its function. The first book to describe microcalorimetric technique in detail, enough for graduate students and research scientists to successfully plumb the structural mysteries of proteins and the double helix, Microcalorimetry of Macromolecules is an essential introduction to using a microcalorimeter in biological studies.

Contenu

1 Introduction 1

2 Methodology 5

2.1 Thermodynamic Basics of Calorimetry 5

2.1.1 Energy 5

2.1.2 Enthalpy 6

2.1.3 Temperature 6

2.1.4 Energy Units 7

2.1.5 Heat Capacity 8

2.1.6 Kirchhoff's Relation 9

2.1.7 Entropy 11

2.1.8 Gibbs Free Energy 13

2.2 Equilibrium Analysis 13

2.2.1 Two-State Transition 13

2.2.2 Derivatives of the Equilibrium Constant 15

2.3 Aqueous Solutions 16

2.3.1 Specifi city of Water as a Solvent 16

2.3.2 AcidBase Equilibrium 18

2.3.3 Partial Quantities 20

2.4 Transfer of Solutes into the Aqueous Phase 23

2.4.1 Hydration Effects 23

2.4.2 Hydrophobic Force 25

2.4.3 Hydration of Polar and Nonpolar Groups 28

References 32

3 Calorimetry 33

3.1 Isothermal Reaction Microcalorimetry 33

3.1.1 The Heat of Mixing Reaction 33

3.1.2 Mixing of Reagents in Comparable Volumes 35

3.1.3 Isothermal Titration Microcalorimeter 36

3.1.4 ITC Experiments 38

3.1.5 Analysis of the ITC Data 41

3.2 Heat Capacity Calorimetry 43

3.2.1 Technical Problems 43

3.2.2 Differential Scanning Microcalorimeter 44

3.2.3 Determination of the Partial Heat Capacity of Solute Molecules 53

3.2.4 DSC Experiments 55

3.2.5 Determination of the Enthalpy of a Temperature-Induced Process 56

3.2.6 Determination of the van't Hoff Enthalpy 58

3.2.7 Multimolecular Two-State Transition 59

3.2.8 Analysis of the Complex Heat Capacity Profile 60

3.2.9 Correction for Components Refolding 61

3.3 Pressure Perturbation Calorimetry 63

3.3.1 Heat Effect of Changing Pressure 63

3.3.2 Pressure Perturbation Experiment 65

References 67

4 Macromolecules 69

4.1 Evolution of the Concept 69

4.2 Proteins 71

4.2.1 Chemical Structure 71

4.2.2 Physical Structure 76

4.2.3 Restrictions on the Conformation of Polypeptide Chains 81

4.2.4 Regular Conformations of Polypeptide Chain Proteins 82

4.3 Hierarchy in Protein Structure 86

4.3.1 Tertiary Structure of Proteins 86

4.3.2 Quaternary Structure of Proteins 88

4.4 Nucleic Acids 89

4.4.1 Chemical Structure 89

4.4.2 Physical Structure 91

References 94

5 The -Helix and -Helical Coiled-Coil 95

5.1 The -Helix 95

5.1.1 Calorimetric Studies of -Helix UnfoldingRefolding 95

5.1.2 Analysis of the Heat Capacity Function 99

5.2 -Helical Coiled-Coils 105

5.2.1 Two-Stranded Coiled-Coils 105

5.2.2 Three-Stranded Coiled-Coils 110

5.3…