Spin Labeling Theory and Applications

We present this special topics volume on an area which has not received thorough coverage for over 12 years. Spin Labeling: Theory and Applications represents a complete update on new theoretical aspects and applications of the spin-label method. In the "line-shape theory" sections, we are especially pleased to include an IBM-compatible diskette supplied by David Schneider and Jack Freed which contains fast, accurate, ready-to-use software for slow-motion simulations. Barney Bales discusses inhomogeneous broadening phenomena in detail. Several developments in techniques and interpretation in saturation transfer spectroscopy have appeared since the publica­ tion of Spin Labeling II: Theory and Applications (L. J. Berliner, ed., Academic Press, 1979). We have included an up-to-date chapter on spin-label applications by M. A. Hemminga and P. A. de Jager. By incorporating 15N and deuterium into nitroxide spin labels, several unique advantages are derived in line-shape analysis. Albert Beth and Bruce Robinson have contributed a detailed chapter on the analysis of these labels in the slow-motion regime while Jane Park and Wolfgang Trommer present the advantages for specific biochemical examples in our "applications" section. Derek Marsh's contri­ bution on spin-label spectral analysis may be regarded as a summary chapter which touches on several of the detailed spectral analysis methods described in the earlier chapters.

1 Calculating Slow Motional Magnetic Resonance Spectra: A User’s Guide.- 1. Introduction.- 2. General Theoretical Considerations.- 2.1. Terms Included in the Liouville and Diffusion Superoperators.- 2.2. Definitions of Coordinate Systems.- 2.3. Basis Vectors and Scalar Product in Operator Space.- 2.4. Construction of the Spin Hamiltonian.- 2.5. Matrix Elements of the Liouville Superoperator.- 2.6. Construction and Matrix Elements of the Diffusion Super-operator.- 2.7. Components of the Starting Vector.- 2.8. The High-Field Approximation.- 3. Magnetic Resonance Line Shapes and the Complex Symmetric Lanczos Algorithm.- 3.1. The Real Symmetric Lanczos Algorithm.- 3.2. The Complex Symmetric Lanczos Algorithm.- 3.3. The Real Symmetric Conjugate Gradients Algorithm.- 3.4. The Complex Symmetric Conjugate Gradients Algorithm.- 3.5. The Continued-Fraction Representation of the Spectral Function.- 3.6. Convergence of the Sequence of Approximate Spectral Functions.- 4. Computational Considerations.- 4.1. Naming Conventions for Files.- 4.2. Array Dimensions and Common Blocks.- 4.3. The Parameter Input Program: LBLL.- 4.4. Spectral Calculations: EPRLL and EPRCGL.- 4.5. Calculation of the Spectral Function: TDLL.- 4.6. “Field Sweep” Conjugate-Gradients Calculations: EPRBL and TNLL.- 4.7. Auxiliary Programs: D200, STVT, MATLST, and VECLST.- 4.8. Porting Programs to Other Machines.- 5. Example Calculations.- 5.1. Model Calculations and General Strategy.- 5.2. Examples from the Literature.- Appendix: Parameters for Example Calculations.- References.- 2 Inhomogeneously Broadened Spin-Label Spectra.- 1. Introduction.- 2. Experimental Determination of Hyperfine Coupling Constants.- 2.1. NMR and ENDOR.- 2.2. ESR Simulation.- 2.3. Solvent Dependence of Hyperfine Coupling Constants.- 3.Gaussian Contributions to Spin-Label Line Shapes.- Example 1.- 4. The Voight Approximation and a One-Parameter Description of Line Shapes.- Example 2.- 5. Line-Shape Comparisons.- 5.1. Unresolved Hyperfine Multiplets.- 5.2. A Universal Nitroxide.- 5.3. Gaussian-Lorentzian Sum Approximations.- 6. Correcting the Linewidth of an Inhomogeneously Broadened Line.- 6.1. Known Hyperfine Coupling Constants.- Example 3. Solvent Dependence of ?HppG.- Example 4. Dependence of ?HppGon Spin-Label Alignment in an Ordered Fluid.- 6.2. Unknown Hyperfine Coupling Constants.- Example 5.- 6.3. Additional Broadening Method.- 7. The Relationship of Linewidth Ratios to Measured Line-Height Ratios.- 7.1. Rotational Correlation Times.- Example 6.- 7.2. Linewidth Ratios Over a Broader Range.- Example 7. Measuring Oxygen Concentrations Using Unresolved Spin-Label Spectra.- 8. Accurate Estimate of Relative Doubly-Integrated Spectral Intensities.- Example 8. A Hypothetical Spin-Label Partitioning Experiment.- 9. Determining Spin-Exchange Frequencies of Spin Labels in Liquids of Low Viscosity.- 10. Deuterated Spin Labels.- 10.1. Gaussian Linewidth of Deuterated Spin Labels.- 10.2. Proton Contamination of a Deuterated Spin Label.- Example 9.- Example 10.- 11. Conclusions.- References.- 3 Saturation Transfer Spectroscopy of Spin Labels: Techniques and Interpretation of Spectra.- 1. Introduction.- 2. Basic Principles of Saturation Transfer ESR.- 2.1. The Spin Hamiltonian.- 2.2. ESR Spectra of Immobilized Spin Labels.- 2.3. The Bloch Equations.- 2.4. Qualitative Explanation of ST-ESR.- 2.5. Spectral Displays of ST-ESR.- 2.6. Analysis of ST-ESR Spectra.- 3. Measurements of Saturation Transfer ESR Spectra.- 3.1. The Resonant Cavity.- 3.2. Effect of Sample on Cavity Properties.- 3.3. Phase-SensitiveDetection.- 3.4. Calibration Procedures.- 3.5. Standard Conditions for ST-ESR Spectroscopy.- 4. Analysis of Saturation Transfer ESR Spectra.- 4.1. Isotropic Motion.- 4.2. Anisotropic Motion.- 5. Future Developments.- References.- 4 Nitrogen-15 and Deuterium Substituted Spin Labels for Studies of Very Slow Rotational Motion.- 1. Introduction.- 2. Overview of Rotational Diffusion Models.- 2.1. Definition of Rotational Correlation Times.- 2.2. Isotropic Rotational Diffusion.- 2.3. Anisotropic Rotational Diffusion in an Isotropic Medium.- 2.4. Uniaxial Rotational Diffusion in an Anisotropic Medium.- 3. Sensitivity of cw-ST-EPR Signals to Rotational Motion.- 3.1. Choice of Signal.- 3.2. Sensitivity to Motion.- 3.3. The Case of Isotropic Motion and Anisotropic Magnetic Tensors.- 3.4. Effects of Anisotropic Motion and Anisotropic Tensors.- 3.5. Geometric Considerations for Analyzing Anisotropic Motion.- 4. Analysis of cw-ST-EPR Data.- 4.1. Isotropic Model Systems.- 4.2. Anisotropic Model Systems.- 4.3. Anisotropic Motional Modeling by Computer Simulations.- 4.4. Overview of Theory for Computation of ST-EPR Spectra.- 5. Studies of Isotropic Motion with Nitrogen-15 Spin Labels.- 5.1. V1EPR Signals as a Function of ?r.- 5.2. Dependence of the V?2Signal on ?r.- 6. Effects of Anisotropic Rotational Diffusion on V?2Spectra.- 6.1. Sensitivity of V?2to Uniaxial Rotation.- 6.2. Effects of Labeling Geometry.- 6.3. Sensitivity of V’2to Anisotropic Rotational Diffusion of Axially Symmetric Ellipsoids in an Isotropic Medium.- 6.4. Relationship between Effective Correlation Times and Anisotropic Motion.- 7. Optimization of Sensitivity of V’2to Motion.- 7.1. Altering Sensitivity to Motion by Selection of v0.- 7.2. Altering Sensitivity to Motion by Selection of vm.- 8. Analysisof Overlapping Motional Species.- 8.1. One Fast and One Slow Motional Component.- 8.2. Two or More Slow Motional Components.- 9. Computer Modeling of Nitrogen-14 V’2Signals.- 9.1. Isotropic Motion Simulations.- 9.2. Anisotropic Motion Simulations.- 9.3. Signal-to-Noise Ratio and Motional Sensitivity of Nitrogen-15 versus Nitrogen-14 Spin Labels.- 10. Saturation Recovery EPR Studies with Nitrogen-15 Spin Labels.- 10.1. Overview of the Experiment.- 10.2. Spectrometer Variables.- 10.3. Strategies for Extraction of Motional Information.- 10.4. Theory of Saturation Recovery.- 10.5. Pseudosecular Terms.- 10.6. Isotropic Brownian Motion—Secular Terms Only.- 10.7. Results of Calculations of SR Curves for Isotropic Motion.- 10.8. Results of Calculations of SR Curves for Nonaxial Tensors.- 10.9. Effects of Pseudosecular Terms.- 10.10. Pseudosecular Terms using Nitrogen-14.- 10.11. Population Analysis: An Estimate of Amplitudes.- 11. Conclusions.- References.- 5 Experimental Methods in Spin-Label Spectral Analysis.- 1. Introduction.- 2. Inhomogeneous Broadening.- 3. Fast Rotational Motion.- 4. Slow Rotational Motion.- 5. Anisotropic Rotation: Lipids/Membranes.- 6. Spin-Spin Interactions and Lateral Diffusion.- 6.1. Spin-Spin Exchange.- 6.2. Translational Diffusion and Bimolecular Collision Rate.- 6.3. Dipolar Spin-Spin Broadening.- 6.4. Separation of Exchange and Dipole-Dipole Interactions.- 7. Lipid-Protein Interactions.- 7.1. Spectral Subtraction/Addition.- 7.2. Measurements at 35 GHz.- 7.3. Analysis of Lipid-Protein Association.- 7.4. Two-Site Exchange Simulations.- 8. Saturation Transfer ESR.- 8.1. Power and Modulation Calibration and the Effects of Sample Shape, Size, and Dielectric Absorption.- 8.2. Anisotropic Rotation.- 8.3. Integral Method: Multicomponent Spectra.-8.4. Dispersion Spectra: Difference Spectroscopy.- References.- 6 Electron-Electron Double Resonance.- 1. Introduction.- 1.1. Definitions and Background.- 1.2. Historical Overview.- 2. Rate Equations.- 3. Spin-Label Relaximetry.- 4. Apparatus.- 5. Applications.- 5.1. Lateral Diffusion in Membranes.- 5.2. Studies Utilizing 14N: 15N Spin-Label Pairs.- 5.3. ELDOR in Cells.- 5.4. Comparison with Spin-Exchange Line Broadening.- 5.5. Further Application of 14N: 15N Methodology.- 6. Future Opportunities.- References.- 7 Resolved Electron-Electron Spin-Spin Splittings in EPR Spectra.- 1. The Scope of Electron Spin-Spin Interactions.- 2. The Nature of Electron Spin-Spin Interactions.- 2.1. Dipolar Interaction.- 2.2. Exchange Interaction.- 2.3. Hamiltonian for Spin-Spin Interaction.- 2.4. Computational Approaches.- 3. Analogies betwe

Dr. Lawrence J. Berliner is currently Professor and Chair of the Department of Chemistry and Biochemistry at the University of Denver after retiring from Ohio State University, where he spent a 32-year career in the area of biological magnetic resonance (EPR and NMR). He is the Series Editor for Biological Magnetic Resonance, which he launched in 1979.