quantification of dynamics in the...
TRANSCRIPT
![Page 1: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/1.jpg)
Quantification of Dynamics in the Solid-State
Bernd Reif
Technische Universität München Helmholtz-Zentrum München
Biomolecular Solid-State NMR Winter School Stowe, VT January 10-15, 2016
• Is there dynamics in the solid-state?
• How does local dynamics compare between solution- and solid-state ?
• How can we quantify dynamics in the solid-state ?
In solutionIn solids
€
R1 (15N) =
d2
10J0 ωH −ωN( ) + 3J1 ωN( ) + 6J2 ωH +ωN( )[ ] +
215c 2J1 ωN( )
€
J(ω) =S2τR
1+ω 2τR2 + 1− SF
2( ) τF1+ω 2τF
2 + SF2 1− SS
2( ) τ S1+ω 2τ S
2
Solution-state: Relaxation is due to molecular tumbling
Solid-state: Relaxation is due to local structural fluctuations
Motivation
1. Solid samples are more susceptible to local structural fluctuations
τc
![Page 2: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/2.jpg)
Measurement of 15N-T1
Solid-State Solution
Chevelkov et al. JCP 128 052316 (2008)
Motivation
2. Temperature dependence of 1H,15N correlations in α-SH3
N-Src loopRT loop
distal loop N- and C-terminus
![Page 3: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/3.jpg)
In solution, things get worse with larger molecular weight
τc
Observables for the quantification of dynamics
- INEPT vs CP based experiments
- T1 Spin-Lattice Relaxation
- T2 Spin-Spin Relaxation
- Order Parameter measurements
- CPMG / R1ρ Relaxation Dispersion
- Heteronuclear NOE
- off- magic angle spinning
⬅ affected by spin density
⬅ rotating methyl groups act as sinks for relaxation
⬅ trivial, but very useful
⬅ spin density ?
⬅ low resolution
⬅ classical observable
!
"
"
"
!
!
⬅ similar to CP/INEPT, quantitative
?
![Page 4: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/4.jpg)
What determines T2 in the solid-state ?
In solution-state: Overall tumbling, τC (local fluctuations, chemical exchange)
In the solid-state:
Not an issue in deuterated samples
LW (adamantane) ≈ 2 Hz
€
T2* = T2
1) Acquisition time
- Insufficient decoupling power - Insufficient MAS frequencies - Probe design
2) Shimming
3) Crystal imperfections
4) Local dynamics ?
LW(1H,13C @ 24 kHz, 600 MHz) > 17 Hz, 4 Hz
τc
Quantification of Dynamics
Relaxation of longitudinal 15N magnetization:
€
R1 (15N) =
d2
10J0 ωH −ωN( ) + 3J1 ωN( ) + 6J2 ωH +ωN( )[ ] +
215c 2J1 ωN( )
€
J(ω) = 1− SF2( ) τF1+ω 2τF
2 + SF2 1− SS
2( ) τ S1+ω 2τ S
2
S: order parameter τ: correlation time τS/τF : Slow and fast motional time scale
In general:
In solution:
τC
€
Cα,α(m, # m )(τ ) = exp −τ /τC( )
€
Y2,mα Ω(0)( ), Y2, $ m
β Ω(τ )( )[ ]
€
J m− # m ωm −ω # m ( ) = dτ0
t
∫ Cα ,β(m, # m )(τ) ⋅ exp i ωm −ω # m ( )τ[ ]
Definition of the spectral density function J(ω):
![Page 5: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/5.jpg)
Quantification of Dynamics in the Solid-State
In Solution-State NMR, relaxation is determined by the tumbling of the molecule in water
In solution
In solids
€
J(ω) = 1− SF2( ) τF1+ω 2τF
2 + SF2 1− SS
2( ) τ S1+ω 2τ S
2€
R1 (15N) =
d2
10J0 ωH −ωN( ) + 3J1 ωN( ) + 6J2 ωH +ωN( )[ ] +
215c 2J1 ωN( )
τS
In Solid-State NMR, relaxation is determined by local structural fluctuations only
τF
1. Measurement of 15N-T1 in the solid-state
Chevelkov et al. J Chem Phys 128 052316 (2008)
€
R1 (15N) =
d2
10J0 ωH −ωN( ) + 3J1 ωN( ) + 6J2 ωH +ωN( )[ ] +
215c 2J1 ωN( )
![Page 6: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/6.jpg)
2. Can we learn something on J(0) in the solid-state ?
Chevelkov et al. JACS 129 10195 (2007)
1) Coherent, Static effect (CSA-dipole correlation) [MAS dependent] 2) Incoherent, Dynamic effect due to Dipole-CSA cross-correlated relaxation [MAS independent]
1) Static effect (CSA-dipole correlation) [MAS dependent]
Composition of Multiplet Intensities
€
δNNz + DHNHzNz = δN + DHN12
+ Hz
#
$ %
&
' ( −
12−Hz
#
$ %
&
' (
*
+ ,
-
. /
0 1 2
3 4 5 Nz
=δN + DHN Hα[ ]δN −DHN H β[ ]0 1 8
2 8
Hβ
Hα
1JNH
Center band
1st spinning side band
![Page 7: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/7.jpg)
1) Static effect (CSA-dipole correlation) [MAS dependent]
Composition of Multiplet Intensities
Hβ
Hα
1JNH
Center band
1st spinning side band
€
δNNz + DHNHzNz = δN + DHN12
+ Hz
#
$ %
&
' ( −
12−Hz
#
$ %
&
' (
*
+ ,
-
. /
0 1 2
3 4 5 Nz
=δN + DHN Hα[ ]δN −DHN H β[ ]0 1 8
2 8
1) Static effect (CSA-dipole correlation) [MAS dependent]
Composition of Multiplet Intensities
Hβ
Hα
1JNH
Center band
1st spinning side band
€
δNNz + DHNHzNz = δN + DHN12
+ Hz
#
$ %
&
' ( −
12−Hz
#
$ %
&
' (
*
+ ,
-
. /
0 1 2
3 4 5 Nz
=δN + DHN Hα[ ]δN −DHN H β[ ]0 1 8
2 8
![Page 8: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/8.jpg)
1) Static effect (CSA-dipole correlation) [MAS dependent]
Composition of Multiplet Intensities
Hβ
Hα
1JNH
Center band
1st spinning side band
€
δNNz + DHNHzNz = δN + DHN12
+ Hz
#
$ %
&
' ( −
12−Hz
#
$ %
&
' (
*
+ ,
-
. /
0 1 2
3 4 5 Nz
=δN + DHN Hα[ ]δN −DHN H β[ ]0 1 8
2 8
Composition of Multiplet Intensities
Is there a contribution due to dynamics ?
€
ΓNH ,Nc ∝
γ HγNrNH3 ⋅ γNB0δN ⋅ (3cos
2 β −1)*τ c
2) Dynamic effect due to Dipole-CSA cross-correlated relaxation [MAS independent]
15N
1JNH
Chevelkov et al. Mag Res Chem 45 S156-160 (2007) Skrynnikov Mag Res Chem 45 S161-173 (2007)
![Page 9: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/9.jpg)
N-Hα/N-Hβ Differential Line Broadening due to Dynamics
MAS = 13 kHz = const
1JNH
Broad Lines in „traditional“ solid-state NMR experiments
Columns
along 15N
T2 decay of 15N-Hα/β allows to access the timescale of local dynamics
Chevelkov et al. MRC 45 S156-160 (2007)
€
ηCSA /DD =12Δln
Iβ
Iα&
' ( (
)
* + + =
dc15
4J0(0) + 3J1(ωN ){ }P2 (cosθ)
![Page 10: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/10.jpg)
Differential T2 decay of α/β multiplet components Teff = 12°C; MAS = 24 kHz
€
ηCSA /DD =12Δln
Iβ
Iα&
' ( (
)
* + + =
dc15
4J0(0) + 3J1(ωN ){ }P2 (cosθ)Chevelkov et al. MRC 45 S156 (2007)
3. 1H-15N dipolar coupling measurements yield Order Parameters
Simulation Parameters:
MAS = 20 kHz Ideal condition: ωRF(1H)/2π = 56 kHz ωRF(15N)/2π = 76 kHz
ΔωRF(15N)/2π = -6 kHz
Wu and Zilm, JMR A 104, 154 (1993) Dvinskikh, Zimmermann, Maliniak and Sandstrøm, JCP 122, 044512 (2005)
Chevelkov, Fink, Reif, J Am Chem Soc 131, 14018 (2009)
![Page 11: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/11.jpg)
Experimental CPPI spectra for α-spectrin SH3
kHz
Error estimation in the determination of 1H,15N dipolar couplings (K18)
LB = Line Broadening of the Exponential Apodization; Dapp = apparent dipolar splitting; DHN = true dipolar coupling (without scaling factor of the pulse sequence)
![Page 12: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/12.jpg)
1H,15N dipolar couplings in α-spectrin SH3
H-bond acceptor
Are variations in the size of the 1HN-15N dipolar coupling due to a variation in the HN-N bond length or
due to dynamics ?
1.035 Å = 11087.8 Hz 1.045 Å = 10772.5 Hz 1.055 Å = 10468.1 Hz
€
DNH = −µ0γ HγN!rNH3
Correlation between the scalar coupling across a hydrogen bond 3hJNC‘ and the1HN isotropic chemical shift
from Cordier and Grzesiek, JACS 121 1601 (1999)
![Page 13: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/13.jpg)
Correlation between the 1HN,15N dipolar couplings and the 1HN isotropic chemical shift
€
DNH = −µ0γ HγN!rNH3
Mob
ility
Increased dynamicsfor weak hydrogen bonds
However: N-H bond length shouldbe increased in a H-Bond
No effect of H-bonding on the N-H bond length
Schanda P, Meier BH, Ernst M Accurate measurement of one-bond H-X heteronuclear dipolar couplings in MAS solid-state NMR. J. Magn. Reson. 210: 246-259 (2011).
Alternatively: Order Parameters via REDOR type experiments
![Page 14: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/14.jpg)
Schanda P, Huber M, Boisbouvier J, Meier BH, Ernst M. Solid-State NMR Measurements of Asymmetric Dipolar Couplings Provide Insight into Protein Side-Chain Motion. Angew. Chem. Int. Ed. 50: 11005-11009 (2012)
Order Parameters via REDOR type experiments
Model-free Analysis to decribe Motion in the Solid-State
€
J(ω ) = 1− SF2( ) τF1+ω 2τF
2 + SF2 1− SS
2( ) τS1+ω 2τS
2
Let's assume that you have slow and fast motions in your protein
There are 4 unknown parameters S2S, S2
F, τS and τF What can we measure?
1H,15N dipole 15N CSA cross-correlated relaxation "15N-T2" 1H,15N dipolar couplings S2
F S2S
15N T1 @ 2 fields
![Page 15: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/15.jpg)
Rmsd minimization of S2S, S2
F, τF and τS
Q16
€
rmsd =1R1,iexp R1,i
theo − R1,iexp( )
#
$ %
&
' (
2
i∑ +
1ηexp
η theo −ηexp( )#
$ % %
&
' ( (
2+ , -
. -
/ 0 -
1 -
1/ 2
Data used for fitting: 15N-T1 (900 MHz) 15N-T1 (600 MHz)
Data used for fitting: 15N-T1 (900 MHz) 15N-T1 (600 MHz) η (15N-CSA / 1H-15N)
S2SS2
F = 0.776; S2S = 0.92
τF = 26 ps
Rmsd minimization of S2S, S2
F, τF and τS
€
rmsd =1R1,iexp R1,i
theo − R1,iexp( )
#
$ %
&
' (
2
i∑ +
1ηexp
η theo −ηexp( )#
$ % %
&
' ( (
2+ , -
. -
/ 0 -
1 -
1/ 2
Data used for fitting: 15N-T1 (900 MHz) 15N-T1 (600 MHz)
Data used for fitting: 15N-T1 (900 MHz) 15N-T1 (600 MHz) η (15N-CSA / 1H-15N)
S2SS2
F = 0.349; S2S = 0.479
τF = 3.9 ns
D62
![Page 16: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/16.jpg)
Order Parameter and τS in α-spectrin SH3
τS and τF in α-spectrin SH3
![Page 17: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/17.jpg)
τS and τF in α-spectrin SH3
Is TROSY beneficial for solid-state NMR?
![Page 18: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/18.jpg)
Observation 1: INEPT based experiments allow to detect residues in mobile regions
Linser et al., J. Am. Chem. Soc. (2010)
Observation 2: Regions which are not detectable in CP experiments undergo a ns-µs time scale dynamics
Quantification of ηCSA/DD using INEPT based experiments
Linser et al., J. Am. Chem. Soc. (2010)
![Page 19: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/19.jpg)
TROSY experiments are beneficial in the solid-state for regions undergoing slow dynamics
Linser et al., J. Am. Chem. Soc. (2010)
Intensities in 2D-HSQC/TROSY and 3D-HNCO/TROSY-HNCO
Using TROSY experiments, the S/N in dynamic regions of the protein can be increased by x2-5
![Page 20: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/20.jpg)
4. heteronuclear NOE measurements: Additional dynamics information in the solid-state
Lopez et al. JBNMR 59 241-249 (2014)
1H,13C heteronuclear NOE measurements
![Page 21: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/21.jpg)
1H,15N heteronuclear NOE measurements
Deuteration is required to avoid spin diffusion
2H R1 rates in Solids and Solution
15N R1 rates in a protonated and deuterated SH3 sample
J. Am. Chem. Soc. 128 12354 (2006)
J. Chem. Phys. 128 052316 (2008)
![Page 22: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/22.jpg)
Aliphatic protons (RAP, Reduction of Adjoining Protonation)
Asami et al., J. Am. Chem. Soc. 2010; Asami et al., Acc. Chem. Res. 2013
✓ 15NH4Cl ✓ [2H,13C]-glucose ✓ 5-30 % H2O (95-70 % D2O)
Experimental 13C T1 decay curves are bi-exponential(25% SH3 RAP sample, 24 kHz MAS)
1. Orientation dependence yieldsfrequency dependent R1 rates→ Mono-exponential initial-rate approximation (Torchia)
2. Spin Diffusion:efficient magnetization transfer to methyls which act as „relaxation sinks“
![Page 23: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/23.jpg)
Dilution of the proton AND carbon spin system 1H,13C correlations of α-SH3: RAP-glucose vs. RAP 2-glycerol
25% RAP-glucose (25 % H2O / 75 % D2O, 2H,13C glucose in M9)
10% RAP-glycerol (10 % H2O / 90 % D2O, [u-2H, 2-13C]-glycerole in M9)
✓ improved resolution (no evolution of J couplings)
✓ simplified spectra: e.g. no Cα labeling for R, Q, E, L, Pno methyl labeling for A, I-γ2, V, L, M
13Cα T1 Decay Curves
25% RAP-glucose, 24 kHz MAS10% RAP-glycerol, 24 kHz MAS10% RAP-glycerol, 50 kHz MAS (mono-exponential)
![Page 24: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/24.jpg)
13Cα T1 in α-spectrin SH3 and MD derived order parameters
Hologne et al. (2005) JACS 127, 11208
3D 2H-13C-13C correlation using 13C-13C RFDR mixing and 2H-13C CPapplied to α-spectrin SH3
5. Protein Side Chain Dynamics
![Page 25: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/25.jpg)
3D-2H,13C,13C Correlation of α-spectrin SH3
2H Pake Pattern for Valine-CD3 in α-spectrin SH3
Conformational exchange is directly reflected in the anisotropy δ and the asymmetry η of the 2H pake pattern (τc < 1/ 52 kHz)
![Page 26: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/26.jpg)
Motional Model for the Side Chain Dynamics of Val-23
Best fit: 2-site jump,jump angle 140° (Center band intensities are not well reproduced in the simulations)
2Hβ Pake Pattern for different Valines in α-spectrin SH3
Lower intensities for V23 indicates motion (τc <≈ 1/160 kHz )
![Page 27: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/27.jpg)
But, ... there are many methyls indicating motion ... ... and no second conformation is visible in the X-ray structure
η=0
η=0 η=1δ1
Comparison of X-Ray Analysis at 100K and RT
Ile-30, 100K Ile-30, RT
Crystal dimensions: RT: 34.5 Å, 42.5 Å, 50.8 Å100 K: 33.6 Å, 42.3 Å, 49.6 Å
B-factors (Å2)main chain RT: 26.9 ; 100K: 13.9side chain RT: 29.6 ; 100K: 17.1whole RT: 28.3 ; 100K: 15.6
ResolutionRT: 1.90 Å; 100 K: 1.49 Å
![Page 28: Quantification of Dynamics in the Solid-Statewinterschool.mit.edu/sites/default/files/documents/Reif...Measurement of 15N-T1 Solid-State Solution Chevelkov et al. JCP 128 052316 (2008)Motivation](https://reader033.vdocument.in/reader033/viewer/2022060413/5f11a3cf91e8357d7375be30/html5/thumbnails/28.jpg)
Acknowledgement
Vipin Agarwal Sam Asami Veniamin Chevelkov Rasmus Linser
Purdue University Nikolai Skrynnikov