Dedication ..................................................... ix
Preface ........................................................ xi
Vector diagrams and animations ................................ xii
How to obtain the animations ................................. xiii
Chapter 1: The simplest one-dimensional NMR experiment .......... 1
1.1 Nuclei are magnets or spins ................................ 2
1.2 Spins align with a field? .................................. 2
1.3 Conservation of angular momentum: spins precess about
a field .................................................... 3
1.4 Quantisation of spin orientation: cone of precession ....... 4
1.5 Thermal energy: net magnetisation .......................... 5
1.6 Magnetisation in the xy-plane: chemical shift and the
rotating frame ............................................. 5
1.7 B1 pulses precess .......................................... 8
Summary ......................................................... 9
Chapter 2: Two additional simple NMR experiments: measuring
T1 and T2 ........................................... 11
2.1 Relaxation: T1 and T2 ..................................... 11
2.2 Measuring T1 .............................................. 12
2.3 Measuring T2 .............................................. 14
2.4 Refocusing chemical shift ................................. 15
2.5 T1 vs T2 .................................................. 15
Summary ........................................................ 16
Chapter 3: J-coupling and the INEPT sequence element ........... 17
3.1 J-coupling ................................................ 17
3.2 1JNH ...................................................... 18
3.3 J-coupling refocuses itself ............................... 19
3.4 Use of 1JNH to transfer magnetisation from 1H to 15N:
spin operators ............................................ 19
3.5 Undesired effects of 1H chemical shift evolution .......... 22
3.6 Simultaneous 180° pulses solve the problem ................ 22
3.7 Creating in-phase 15N magnetisation ....................... 23
3.8 Advantages of using 1JNH to create 15N excitation: INEPT ... 27
Summary ....................................................... 28
Chapter 4: The HSQC experiment (coupled, decoupled and
gradient versions) .................................. 29
4.1 The coupled 1H,15N-HSQC ................................... 29
4.2 Detecting the 15N chemical shift via t1 incrementation .... 29
4.3 The decoupled 1H,15N-HSQC ................................. 32
4.4 Pulsed field gradients [PFGs] ............................. 32
4.5 PFG versions of the HSQC .................................. 35
4.6 PFG nomenclature .......................................... 38
Summary ........................................................ 39
Chapter 5: 3D HSQC-based double resonance experiments .......... 41
5.1 Double resonance experiments .............................. 42
5.2 NOESY-HSQC ................................................ 42
5.3 TOCSY-HSQC ................................................ 46
Summary ........................................................ 49
Chapter 6: 3D HSQC-based triple resonance experiments .......... 51
6.1 Triple resonance .......................................... 51
6.2 HNCO ...................................................... 53
6.3 HNCA ...................................................... 57
6.4 HN[CO]CA .................................................. 60
Summary ........................................................ 63
Chapter 7: 2D HSQC-based lbN relaxation experiments ............ 65
7.1 15NT1 ...................................................... 65
7.2 15NT2 ...................................................... 69
7.3 1H,15N ..................................................... 69
Summary ........................................................ 71
Appendix A: Fourier transform, sign discrimination, artefact,
suppression ........................................ 73
A.1 FID ....................................................... 73
A.2 Oscillatory components and decay rates → frequency and
line width ................................................ 73
A.3 Quadrature detection in the direct dimension .............. 73
A.4 Artefacts associated with quadrature detection: Ql and
QG ........................................................ 74
A.5 Phase cycling: removing artefacts ......................... 76
A.6 Placing H20 at the centre ................................. 77
A.7 Aliasing .................................................. 77
A.8 Sign discrimination in the indirect dimension: States
and TPPI .................................................. 78
A.9 States-TPPI ............................................... 79
Summary ........................................................ 80
Appendix B: Extracting dynamic information from relaxation
data ............................................... 81
B.l Global and internal correlation times ..................... 81
B.2 Dominant 15N relaxation mechanisms ........................ 81
B.3 Dipolar coupling [DD] ..................................... 82
B.4 Chemical shift anisotropy [CSA] ........................... 83
B.5 Spectral density function ................................. 83
B.6 Relaxation parameters are determined by J(ω) .............. 85
B.7 R1 ≥ R2 ................................................... 86
B.8 Internal motions change J(ω) .............................. 87
B.9 Changes in J(ω) change T1, T2 and NOE ..................... 88
B.10 More complex motions and relaxation ....................... 88
Summary ........................................................ 89
Appendix C: Additional HSQC options: sensitivity enhancement,
TROSY, deuteration ................................. 91
C.l Sensitivity enhanced HSQC [SE-HSQC) ....................... 91
C.2 Gradient selection with sensitivity enhancement
(GSE-HSQC] ................................................ 93
C.3 Practical considerations of SE-HSQC and GSE-HSQC .......... 95
C.4 TR0SY: Transverse Relaxation-Optimised Spectroscopy ....... 95
C.5 Deuteration and TROSY ..................................... 96
Summary ....................................................... 100
Appendix D: HMQC .............................................. 101
Appendix E: Miscellaneous concepts ............................ 105
E.l Chemical exchange ........................................ 105
E.2 Radiation damping ........................................ 105
E.3 Initial t1 value ......................................... 106
E.4 Relaxation-optimised INEPT delays ........................ 107
E.5 Bloch-Siegert effect and Bloch-Siegert compensating
pulses (BSCP) ............................................ 108
Appendix F: Selected bibliography [some of my favourite
books] ............................................ 111
Appendix G: Partial pulse sequence and concept bibliography ... 113
G.l Bloch-Siegert compensating pulses ........................ 113
G.2 Constant time ............................................ 113
G.3 CPMG ..................................................... 113
G.4 CYCLOPS .................................................. 114
G.5 Deuteration .............................................. 114
G.6 Echo-antiecho ............................................ 114
G.7 EXORCYCLE ................................................ 114
G.8 GSE-HSQC ................................................. 115
G.9 HMQC ..................................................... 115
G.10 HN(CO]CA ................................................. 115
G.11 HNCA ..................................................... 115
G.12 HNCO ..................................................... 115
G.13 HSQC ..................................................... 116
G.14 Hypercomplex ............................................. 116
G.15 INEPT .................................................... 116
G.16 NOESY .................................................... 116
G.17 Relaxation ............................................... 117
G.18 Sensitivity enhancement .................................. 117
G.19 States-TPPI .............................................. 117
G.20 TOCSY .................................................... 117
G.21 TOCSY-HSQCand NOESY-HSQC ................................. 118
G.22 TPPI ..................................................... 118
G.23 TROSY .................................................... 118
Appendix H: Symbols and definitions ........................... 119
Appendix I: Creating the cover image .......................... 121
Appendix J: Index ............................................. 123
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