TITAN: Two-dimensional lineshape analysis Chris Waudby - - PowerPoint PPT Presentation
TITAN: Two-dimensional lineshape analysis Chris Waudby - - PowerPoint PPT Presentation
TITAN: Two-dimensional lineshape analysis Chris Waudby Christodoulou Group c.waudby@ucl.ac.uk Andres Ramos Lisa Cabrita John Christodoulou Inhibition of fatty acid synthesis for treatment of tularemia OH Cl O Cl Cl OH O Cl OH O OH
Inhibition of fatty acid synthesis for treatment of tularemia
O OH Cl Cl Cl O OH Cl O OH O OH
2
O OH
5
Inhibition of Francisella tularensis enoyl reductase (interaction of inhibitors with E–NAD+ complex)
Lu, H. et al. ACS Chem. Biol. 4, 221–231 (2009) Copeland, R. A. Nat Rev Drug Discov 15, 87–95 (2016)
Inhibition of fatty acid synthesis for treatment of tularemia
O OH Cl Cl Cl O OH Cl O OH O OH
2
O OH
5
Lu, H. et al. ACS Chem. Biol. 4, 221–231 (2009) Copeland, R. A. Nat Rev Drug Discov 15, 87–95 (2016)
Survival (%)
100 80 60 40 20 1.0 1.5 2.0 2.5 3.0 0.5
Ki (nM)
a
In vivo . Lu et al. the relationship between the residence time of a series of Fabl enoyl‑reductase inhibitors and in vivo
- activity. The plots presented here show the percent survival of mice 10 days after they were infected
Francisella tularensis and then treated with the inhibitors. Correlation of percent ). Correlation of percent survival with inhibitor residence
- time. Figure is adapted with permission from
, Wiley.
Inhibition of fatty acid synthesis for treatment of tularemia
O OH Cl Cl Cl O OH Cl O OH O OH
2
O OH
5
Lu, H. et al. ACS Chem. Biol. 4, 221–231 (2009) Copeland, R. A. Nat Rev Drug Discov 15, 87–95 (2016)
3.0
Survival (%)
100 80 60 40 20 160 140 120 100 80 60 40 20
Residence time (minutes)
b
In vivo . Lu et al. the relationship between the residence time of a series of Fabl enoyl‑reductase inhibitors and in vivo
- activity. The plots presented here show the percent survival of mice 10 days after they were infected
Francisella tularensis and then treated with the inhibitors. Correlation of percent ). Correlation of percent survival with inhibitor residence
- time. Figure is adapted with permission from
, Wiley.
Kinetics of ligand binding are crucial to in vivo activity
Molecular mechanism of imatinib (Gleevec)
Agafonov, R. V., Wilson, C., Otten, R., Buosi, V. & Kern, D. Nat. Struct. Mol. Biol. 21, 848–853 (2014) Wilson, C. et al. Science 347, 882–886 (2015)
Mechanism of binding is central to activity
∆ν
Rates of reactions and spectroscopic timescales
NMR UV frequency difference ∆ν ~ 1014 Hz kex ≪ ∆ν NMR frequency difference ∆ν ~ 100 Hz kex ≫ ∆ν UV ∆ν
http://casegroup.rutgers.edu/lnotes/NMR_lecture_dynamics.pdf
100% A 100% B slow exchange
NMR lineshapes vs exchange rates
A ⌦ B
3 s–1 frequency difference 200 s–1
100% A 100% B slow-intermediate exchange
NMR lineshapes vs exchange rates
A ⌦ B
30 s–1 frequency difference 200 s–1
100% A 100% B fast-intermediate exchange
NMR lineshapes vs exchange rates
A ⌦ B
300 s–1 frequency difference 200 s–1
100% A 100% B fast exchange
NMR lineshapes vs exchange rates
A ⌦ B
3000 s–1 frequency difference 200 s–1
NMR lineshapes vs exchange rates
http://casegroup.rutgers.edu/lnotes/NMR_lecture_dynamics.pdf
magnetic field strength
NMR titrations are information rich
structure (chemical shifts) molecular weight (linewidths) P PL ‡ free energy binding kinetics thermodynamics (∆G = RT ln Kd)
∆ν ~ 10 – 10,000 s–1 => measure exchange on timescales of µs – s
NMR lineshape analysis
spin system parameters chemical shifts linewidths (relaxation rates) binding model parameters Kd, koff…
chemical shift ligand concentration
Bloch-McConnell equations
P + L ⌦ PL kex = koff + kon[L]
ligand concentration / µM 50 100 150 1 fraction bound chemical shift true fraction bound
NMR lineshape analysis
spin system parameters chemical shifts linewidths (relaxation rates) binding model parameters Kd, koff…
chemical shift ligand concentration
Bloch-McConnell equations
NMR lineshape analysis
example: ultrafast folding (10 µs timescale) of villin headpiece
Wang, M. et al. J. Am. Chem. Soc. 125, 6032–6033 (2003)
From 1D to 2D…
1H chemical shift / ppm 15N chemical shift / ppm
7.0 7.5 8.0 8.5 7.0 7.5 8.0 8.5 108 110 112 114 116 108 110 112 114 116
Lineshape analysis of 1D cross-sections
O'Connor, C. & Kovrigin, E. L. Biochemistry 51, 9638–9646 (2012)
Why isn’t lineshape analysis more common?
- Apathy – ‘Good enough’ to assume fast/slow exchange
and analyse chemical shift/intensity changes?
- No! This risks systematic errors and ignores the
richness of titration datasets
- Complexity of analysis?
- Software needs to be easy to use!
Problem #1: Peak overlap
Problem #2: Normalisation
1H
1D pulse-acquire: 2D HSQC: signals decay during pulse program execution no delay between pulse and acquisition => signal proportional to concentration
Problem #2: Normalisation
7.3 7.4 7.5 7.6 7.7
Raw intensities
7.3 7.4 7.5 7.6 7.7
1H chemical shift / ppm Normalised peak volumes
Problem #2: Normalisation
7.3 7.4 7.5 7.6 7.7
Raw intensities
7.3 7.4 7.5 7.6 7.7
1H chemical shift / ppm Normalised peak volumes
7.3 7.4 7.5 7.6 7.7
Spectra with measurement noise
7.3 7.4 7.5 7.6 7.7
1H chemical shift / ppm Normalised peak volumes
Problem #3: Differential relaxation
1H
1D pulse-acquire: 2D HSQC: signals decay during pulse program execution no delay between pulse and acquisition => signal proportional to concentration
Problem #4: Multiple quantum evolution
7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117
1H chemical shift / ppm 1H chemical shift / ppm
HSQC HMQC
0 eq 0.25 eq 0.5 eq 0.75 eq 1 eq 2 s
– 1
2 s
– 1
2 s
– 1
2 s
– 1
ligand concentration dissociation rate [P]0 = 100 µM 700 MHz
ΔδH = 0.1 ppm ΔδN = 0 ppm
7.4 7.5 7.6 7.7
1H chemical shift / ppm
HMQC appears to have more binding than in HSQC
There must be a better way! Existing methods – at best – analyse 2D data using 1D theory…
Two-dimensional lineshape analysis
spin system parameters chemical shifts linewidths (relaxation rates) binding model parameters Kd, koff…
QM
7 7.5 8 114 115 116 117 114 115 116 117
1H chemical shift / ppm 15N chemical shift / ppm
Two-dimensional lineshape analysis
spin system parameters chemical shifts linewidths (relaxation rates) binding model parameters Kd, koff…
QM
7 7.5 8 114 115 116 117 114 115 116 117
1H chemical shift / ppm 15N chemical shift / ppm
Two-dimensional lineshape analysis
spin system parameters chemical shifts linewidths (relaxation rates) binding model parameters Kd, koff…
QM
pulse program +experimental settings +processing parameters
7 7.5 8 114 115 116 117 114 115 116 117
1H chemical shift / ppm 15N chemical shift / ppm
Pulse programs / degrees of freedom
Evolution of isolated IS spin system (without chemical exchange): How many parameters can we expect to extract from a spectrum?
Helgstrand, M., Härd, T. & Allard, P. J. Biomol. NMR 18, 49–63 (2000)
16 free parameters!
Two-dimensional lineshape analysis
Helgstrand, M., Härd, T. & Allard, P. J. Biomol. NMR 18, 49–63 (2000) Helgstrand, M. & Allard, P. J. Biomol. NMR 30, 71–80 (2004)
Two-dimensional lineshape analysis
✓ No normalisation required between spectra ✓ Accounts for differential relaxation and MQ evolution
during pulse sequence
✓ Can avoid regions of peak
- verlap or fit overlapping
signals simultaneously
8.4 8.5 8.6 8.7 120 120.5 121 121.5 122
1H chemical shift / ppm 15N chemical shift / ppm
Example: FIR / Nbox interaction
FBP FUSE ssDNA GT rich RRM1 RRM2 Nbox FIR
Lineshape analysis: FIR / FBP Nbox
- bserved
fit
- bserved
fit Kd = 14 ± 8 µM Kd = 22.7 ± 0.5 µM reported: fit: koff = 2700 ±100 s–1 RRM1 RRM2 Nbox FIR
Lineshape analysis: FIR / FBP3 Nbox
Kd = 280 ± 36 µM Kd = 283 ± 2 µM reported: fit: koff = 15000 ± 300 s–1
- bserved
fit RRM1 RRM2 Nbox3 FIR
Global fit of 18 residues:
10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 10.7 10.8 10.9 11 11.1 121 121.5 122 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 8.8 9 9.2 114 115 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 9.3 9.4 9.5 115.5 116 116.5 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7.8 7.9 8 110 111 112 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 7 7.2 121 122 123 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.4 8.6 127.5 128 128.5 129 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.2 8.3 8.4 115 116 117 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.7 8.8 8.9 9 125 126 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.3 8.4 106 106.5 107 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 8.95 9 9.05 9.1 9.15 131.5 132 132.5 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 9.1 9.15 9.2 9.25 123 123.5 124 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126 7.9 8 8.1 125 125.5 126
3D plots for inspecting goodness of fit
7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25 7 7.1 7.2 7.3 121 122 123 0.05 0.1 0.15 0.2 0.25
0 eq 0.1 eq 0.3 eq 0.6 eq 1.15 eq 1.7 eq 2.3 eq 2.9 eq 3.5 eq 4.6 eq 5.8 eq 6.9 eq 8.6 eq 11.5 eq 14.3 eq
- bserved
fitted
Example 2: TFP binding to (Ca2+)4-CaM
F S N N N F F
trifluoperazine
8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68 8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68
NMR titration
8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68 8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68 8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68
8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68 8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68
Full binding model: 16 states, 32 equilibria
8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68 8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68 8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68
8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68 8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68
Sequential binding model
8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68 8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68 8.4 8.6 8.8 9 123 124 125 126
1H chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68
2D lineshape fitting to sequential binding model
8.4 8.6 8.8 9 123 124 125 126 8.4 8.6 8.8 9 123 124 125 126
b
- bserved
fitted
1H chemical shift / ppm 1H chemical shift / ppm 15N chemical shift / ppm 15N chemical shift / ppm
K115 F141 D118 D80 I63 S101 F68
c d e f
1 2 3 4 4 1 2 3 1 2 3 4
CaM 2270 ± 100 s-1 +TFP, 14 ± 1 μM CaM:TFP1 2070 ± 80 s-1 +TFP, 25 ± 1 μM CaM:TFP2 11000 ± 400 s-1 +TFP, 62 ± 2 μM CaM:TFP3 12000 ± 3000 s-1 +TFP, 4 ± 1 mM CaM:TFP4
a
based on global fit of 33 residues
TITAN: Easy to use 2D analysis software
www.nmr-titan.com
Use a variety of build-in binding models
www.nmr-titan.com
Define regions of interest to avoid overlap
www.nmr-titan.com
…or fit overlapping peaks directly
www.nmr-titan.com
Check fit quality with 3D viewer
Error analysis by block residual resampling (bootstrapping)
Validation and comparison of simple and block resampling
−3 −2 −1 1 2 3 −10 −8 −6 −4 −2 2 4 6 8
Standard Normal Quantiles z-score QQ plot: parameter z-scores vs Standard Normal
Kd=1 μM, koff=5 s−1, σ=0.2
115 116
Kd=1 μM, koff=5 s−1, σ=0.5 Kd=100 μM, koff=5000 s−1, σ=0.5 Kd=10 μM, koff=500 s−1, σ=0.2
115 116
Kd=10 μM, koff=500 s−1, σ=0.1 Kd=100 μM, koff=5000 s−1, σ=0.1 Kd=1 μM, koff=5000 s−1, σ=0.5
7.5 7.6 115 116
Kd=1 μM, koff=500 s−1, σ=0.1
7.5 7.6
Kd=10 μM, koff=5000 s−1, σ=0.5
7.5 7.6
Simple bootstrap (N=1) Block bootstrap (N=5) simulate noisy synthetic data with parameters p0 fit data to estimate parameters, pfit calculate bootstrap error estimates, σ analyse distribution
- f z-scores
z = (pfit – p0) / σ
1H chemical shift / ppm 15N chemical shift / ppm
Protein-ligand titrations were simulated with a fixed protein concentration of 50 µM and ligand concentrations of 0, 12.5, 25, 50, 62.5 and 75 µM, with Kd varied between 1 and 100 µM and koff between 5 and 5000 s–1. The performance of the fitting algorithm was investigated with different levels of noise in the synthetic dataset.
Exchange in HSQC vs HMQC spectra
7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117 7.5 7.6 116 117
1H chemical shift / ppm 1H chemical shift / ppm
HSQC HMQC
0 eq 0.25 eq 0.5 eq 0.75 eq 1 eq 2 s
– 1
2 s
– 1
2 s
– 1
2 s
– 1
ligand concentration dissociation rate [P]0 = 100 µM 700 MHz
ΔδH = 0.1 ppm ΔδN = 0 ppm
7.4 7.5 7.6 7.7
1H chemical shift / ppm
HMQC appears to have more binding than in HSQC
Chemical exchange regimes
http://casegroup.rutgers.edu/lnotes/NMR_lecture_dynamics.pdf
magnetic field strength
ξ = ∆ω kex
Introduce the dimensionless parameter: Coalescence point (50:50 equilibrium)
ξ = √ 2 ξ p 2 ξ ⌧ p 2
Fast exchange Slow exchange
- 4
- 2
2 4
- 4
- 2
2 4 ξI ξS
Chemical exchange regimes in 2D experiments: I-spin only
ξI = ∆ωI kex
ξS = ∆ωS kex
F S
∆ωobs =∆ωIpB Rex =∆ω2
I pApB
kex ∆ωobs =k2
expApB
∆ωI Rex =kAB
F S S
Chemical exchange regimes in 2D experiments: HSQC
- 4
- 2
2 4
- 4
- 2
2 4 ξI ξS
ξI = ∆ωI kex
ξS = ∆ωS kex
F S S F S F S S
∆ωobs =k2
expApB
∆ωS Rex =kAB ∆ωobs =∆ωSpB Rex =∆ω2
SpApB
kex
- 4
- 2
2 4
- 4
- 2
2 4 ξI ξS
Chemical exchange regimes in 2D experiments: HZQC
ξI = ∆ωI kex
ξS = ∆ωS kex
F S F S S
∆ωobs =(∆ωS − ∆ωI)pB Rex =(∆ωS − ∆ωI)2pApB kex
∆ωobs = k2
expApB
∆ωS − ∆ωI Rex =kAB
∆ωobs = k2
expApB
∆ωS + ∆ωI Rex =kAB
∆ωobs =(∆ωS + ∆ωI)pB Rex =(∆ωS + ∆ωI)2pApB kex
- 4
- 2
2 4
- 4
- 2
2 4 ξI ξS
fast exchange (I-spin SQ) fast exchange (S-spin DQ)
Chemical exchange regimes in 2D experiments: HDQC
ξI = ∆ωI kex
ξS = ∆ωS kex
F S F S S
- 4
- 2
2 4
- 4
- 2
2 4 ξI ξS
Chemical exchange regimes in 2D experiments: HMQC
ξI = ∆ωI kex
ξS = ∆ωS kex
SS– SS+ FF
∆ωobs =∆ωSpB Rex =(∆ω2
S + ∆ω2 I )pApB
kex
∆ωobs =k2
expApB∆ωS
∆ω2
S − ∆ω2 I
Rex =kAB
SZSD FZFD
Skrynnikov (2002)
- 4
- 2
2 4
- 4
- 2
2 4 ξI ξS
Example: fast/fast exchange
∆ωobs =∆ωSpB Rex =(∆ω2
S + ∆ω2 I )pApB
kex
FZFD
- 0.1
0.1 0.2 0.3 0.4 0.5 0.6
∆ δN / ppm
10 20 30 40 50 60 70 80 90 100
- 0.1
0.1 0.2 0.3 0.4 0.5 0.6
∆ δN / ppm
10 20 30 40 50 60 70 80 90 100
MQ 15N lineshape SQ 15N lineshape kex 1000 s–1 ∆wN 200 s–1 ∆wH 200 s–1
- 0.5
0.5 1 1.5 2 2.5
∆ δN / ppm
10 20 30 40 50 60 70
MQ 15N lineshape
- 0.5
0.5 1 1.5 2 2.5
∆ δN / ppm
10 20 30 40 50 60 70
SQ 15N lineshape kex 1000 s–1 ∆wN 1000 s–1 ∆wH 1750 s–1
- 4
- 2
2 4
- 4
- 2
2 4 ξI ξS
Example: slow/slow exchange SZSD
∆ωobs =k2
expApB∆ωS
∆ω2
S − ∆ω2 I
Rex =kAB
- 4
- 2
2 4
- 4
- 2
2 4 ξI ξS
fast exchange (I-spin SQ) fast exchange (S-spin MQ)
MQ coalescence point
ξI = ∆ωI kex
ξS = ∆ωS kex
Summary: 2D fast exchange regimes
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
HSQC
,
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
HMQC
,
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
HZQC
,
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
HDQC
,
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
SIM-H[Z/D]QC
The SOFAST-SIM-H[Z/D]QC experiment
Separate HZQC and HDQC by post- acquisition receiver phase cycling Sensitivity – each experiment = 1/√2 of HSQC
1H 15N
Gz t1
decouple
g1 g2 g2
δ δ x,–x
500 1000 1500 2000 2500 3000 3500
Acquisition + recycle delay / ms
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Sensitivity
120 degree excitation 90 degree excitation
The SIM-H[Z/D]QC experiment: cyclophilin
HZQC
1H chemical shift / ppm
7.0 8.0 9.0 10.0 90 100 110 120 130 140 150
HDQC
1H chemical shift / ppm
7.0 8.0 9.0 10.0 90 100 110 120 130 140 150
Summary: 2D fast exchange regimes
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
HSQC
,
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
HMQC
,
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
HZQC
,
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
HDQC
,
- 3
- 2
- 1
1 2 3
- 3
- 2
- 1
1 2 3 ξI ξS
SIM-H[Z/D]QC
Paramagnetic longitudinal relaxation enhancement
Chan, Waudby et al. J Biomol NMR (2015) 63 151–163 Cai et al. JACS (2006) 128, 13474–13478
R1,p ≈ R2,p = 20S(S + 1)µ2
Bg2
15r6 γ2T1e
(T1e ⌧ τc)
δN / ppm SNRt / s-½
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0.0 0.2 0.4 0.8 0.6 110 115 120 125
δH / ppm
Trec / s
7.0 7.5 8.0 8.5 1.0
δ δ
a b d
SNR / s
Δ
e
Δ [NiDO2A] / mM 20 40 60 80
40 mM NiDO2A 0 mM NiDO2A
Summary
- NMR titrations – a powerful tool for characterising structural,
mechanistic, thermodynamic and kinetic aspects of macromolecular interactions
- Introduction of 2D lineshape analysis
– more accurate (differential relaxation, normalisation) – more convenient (peak overlap) – block residual resampling method for error analysis
- Applications to simple ligand binding but also more complex models
- Comparison of SQ, MQ, ZQ and DQ experiments provides
additional and complementary information on exchange phenomena
- Download now for Mac and Linux! www.nmr-titan.com