Biomolecular EPR Spectroscopy

by Wilfred Raymond Hagen

Overview

Comprehensive, Up-to-Date Coverage of Spectroscopy Theory and its Applications to Biological Systems

Although a multitude of books have been published about spectroscopy, most of them only occasionally refer to biological systems and the specific problems of biomolecular EPR (bioEPR). Biomolecular EPR Spectroscopy provides a practical introduction to bioEPR and demonstrates how this remarkable tool allows researchers to delve into the structural, functional, and analytical analysis of paramagnetic molecules found in the biochemistry of all species on the planet.

A Must-Have Reference in an Intrinsically Multidisciplinary Field

This authoritative reference seamlessly covers all important bioEPR applications, including low-spin and high-spin metalloproteins, spin traps and spin lables, interaction between active sites, and redox systems. It is loaded with practical tricks as well as do’s and don’ts that are based on the author’s 30 years of experience in the field. The book also comes with an unprecedented set of supporting software designed with simple graphical user interfaces that allow readers to tackle problems they will likely encounter when engaged in spectral analysis.

Breaking with convention, the book broaches quantum mechanics from the perspective of biological relevance, emphasizing low-symmetry systems. This is a necessary approach since paramagnets in biomolecules typically have no symmetry. Where key topics related to quantum mechanics are addressed, the book offers a rigorous treatment in a style that is quick-to-grasp for the non expert. Biomolecular EPR Spectroscopy is a practical, all-inclusive reference sure to become the industry standard.

Product Details

ISBN-13:	9780367577407
Publisher:	CRC Press
Publication date:	06/30/2020
Pages:	262
Product dimensions:	6.12(w) x 9.19(h) x (d)

About the Author

Wilfred Raymond Hagen

Table of Contents

Preface xi

Part 1 Basics

Chapter 1 Introduction 3

1.1 Overview of biomolecular EPR spectroscopy 3

1.2 How to use this book and associated software 4

1.3 A brief history of bioEPR 5

Chapter 2 The Spectrometer 9

2.1 The concept of magnetic resonance 9

2.2 The microwave frequency 12

2.3 Overview of the spectrometer 15

2.4 The resonator 17

2.5 From source to detector 20

2.6 The magnet 22

2.7 Phase-sensitive detection 23

2.8 Tuning the spectrometer 25

2.9 Indicative budget considerations 27

Chapter 3 The Sample 33

3.1 Sample tube and sample size 33

3.2 Freezing and thawing 36

3.3 Solid air problem 39

3.4 Biological relevance of a frozen sample 40

3.5 Sample preparation on the vacuum/gas manifold 43

3.6 Choice of reactant 47

3.7 Gaseous substrates 49

3.8 Liquid samples 50

3.9 Notes on safety 51

Chapter 4 Experimental Key Parameters 53

4.1 Boltzmann and Heisenberg dictate optimal (P,T) pairs 53

4.2 Homogeneous versus inhomogeneous lines 58

4.3 Spin multiplicity and its practical implications 61

Chapter 5 Resonance Condition 67

5.1 Main players in EPR theory: B, S, and I 67

5.2 Anisotropy 71

5.3 Hyperfine interactions 75

5.4 Second-order effects 78

5.5 Low-symmetry effects 80

5.6 Zero-field interactions 82

5.7 Integer spins 87

5.8 Interpretation of g, A, D 89

Chapter 6 Analysis 95

6.1 Intensity 95

6.2 Quantification 96

6.3 Walking the unit sphere 100

6.4 Difference spectra 103

Part 2 Theory

Chapter 7 Energy Matrices 109

7.1 Preamble to Part 2 109

7.2 Molecular Hamiltonian and spin Hamiltonian 112

7.3 Simple example: S = 1/2 115

7.4 Not-so-simple example: S = 3/2 119

7.5 Challenging example: integer spin S ≥ 2 123

7.6 Compounded (or product) spin wavefunctions 131

Chapter 8 Biological Spin Hamiltonians 135

8.1 Higher powers of spin operators 135

8.2 Tensor noncolinearity 140

8.3 General EPR intensity expression 141

8.4 Numerical implementation of diagonalization solutions 145

8.5 A brief on perturbation theory 147

Chapter 9 Conformational Distributions 153

9.1 Classical models of anisotropic linewidth 153

9.2 Statistical theory of g-strain 157

9.3 Special case of full correlation 159

9.4 A (bio)molecular interpretation of g-strain 162

9.5 A-strain and D-strain: coupling to other interactions 164

Part 3 Specific Experiments

Chapter 10 Aqueous Solutions 169

10.1 Spin traps 169

10.2 Spin labels in isotropic media 171

10.3 Spin labels in anisotropic media 177

10.4 Metalloproteins in solution 179

Chapter 11 Interactions 181

11.1 Dipole-dipole interactions 181

11.2 Dipolar interaction in multicenter proteins 184

11.3 Exchange interactions 188

11.4 Spin ladders 193

11.5 Valence isomers 196

11.6 Superparamagnetism 197

Chapter 12 High Spins Revisited 199

12.1 Rhombograms for S = 7/2 and S = 9/2 199

12.2 D-strain modeled as a rhombicity distribution 204

12.3 Population of half-integer spin multiplets 205

12.4 Intermediate-field case for S = 5/2 207

12.5 Analytical lineshapes for integer spins 208

Chapter 13 Black Box Experiments 213

13.1 EPR-monitored binding experiments 214

13.2 EPR monitoring of redox states 215

13.3 EPR monitored kinetics 221

13.4 EPR of whole cells and organelles 222

Chapter 14 Strategic Considerations 225

14.1 Bio-integrated bioEPR 225

14.2 To be advanced or not to be advanced 226

14.3 Friday afternoon experiment 228

References 231

Index 241

Editorial Reviews

"EPR is being increasingly used to investigate biological systems, but there is currently no text that biologists, biochemists, and bioinorganic chemists can use to understand the experimental and theoretical aspects of this technique without being experts in quantum mechanics… provides a valuable introductory text that can be recommended… The author is a prolific writer with a clear and concise writing style."

—Michael K. Johnson, Department of Chemistry, University of Georgia, Athens, USA

From the Publisher