BCMB/CHEM 8190

• Magic Angle Spinning (MAS)
• High Power Decoupling
• Cross Polarization (CP)
• Assignment Strategies
• Structural Information

z

 r
B
0

1 r

2 x
 y
E = (

0
/4

)((

1
·

2
)/r 3 – 3( 
1
· r )(

2
· r )/r 5 ) r = i r x
+ j r y
+ k r z
= i r sin
 cos

+ j r sin
 sin

+ k r cos


First Order QM Term ( I z1
I z2
) is most Important
A doublet results – much like scalar coupling but large:

60,000 Hz for a 13 C1 H pair,

250,000 Hz for 1 H1 H .
Splittings are angle dependent – ranging from
-60,000 to +30,000 for 13 C1 H. All possibilities superimpose: The result is a powder pattern
Points at 90º on a sphere are most abundant
D

H = H
CSA
+ H
D
+ H
Q
...
2

2

CSA powder pattern

• All interactions can be written in terms of Y 2
0
(

) = (3cos 2 (

) –1)/2
• Y 2
0
(

) can be transformed to another frame using Wigner Rotation elements: Y 2
0
(

) =

2 m=-2
D 2 m0
(
 ’’,  ’’) Y 2 m
(
 ’,  ’)
• D 2 m0
(
 ’’,  ’’) = (4 
/5) Y 2 m
(
 ’’,  ’’)
• With rapid averaging over  ’’, all terms except Y 2
0
(
 ’’) go to zero
• Selecting  ’’ = 54.7

, all interactions, regardless of
 ’ value, are zero
• (3cos 2 (

) –1) = (3cos 2 (
 ’)–1) <3cos 2 (54.7

) –1> = 0
Z
 ’’
Dipolar couplings
CSA
Quadrupolar couplings
= 0

’’
X

 ’
Y

• MAS only works if rate >> D
– Maximum rate ~50 kHz, typical 10kHz
– High speed rotors ~ 1mm diameter
• Decoupling helps
– Easy in solution 13 C1 H J = ~125 Hz
– Solids 13 C1 H J + D = ~60 kHz
• Solution is to do both

What is this peak?
(10 minute spectra)
13 C

Magnetization transfer via dipolar coupling.
Hartman-Hahn: g
I
B
I
= g
S
B
S

When rotation rate is not >> anisotropies
Resonance position is modulated by rotation
Sidebands at the spinning frequency are produced
There are tricks that remove these:
TOSS – Total Suppression of Spinning Sidebands
180º pulses during rotor cycle dephases sideband magnetization but preserves center band magnetization

Peptide
1,213 C
2
-Gly
(9 minute spectra)

here: proton driven spin diffusion
Aliphatic region of the 13 C, 13 C CP MAS PDSD of Zn-MMP-12 (16.4 T,
11.5 kHz MAS frequency, 15 ms mixing time). ( Balayssac, Oschkinat, 2007)

Experiments can parallel solution assignment strategies
(C) Backbone walk for the A21
–A28 stretch of residues in LC8 using three-dimensional NUS-PACC NCACB and NCOCA experiments. The total experiment times are 27 and 9 h for the NCACB and NCOCA experiments, respectively. Reproduced with permission from ref 6. Copyright 2012 American Chemical Society.
Published in: Si Yan; Christopher L. Suiter; Guangjin Hou; Huilan Zhang; Tatyana Polenova; Acc. Chem. Res.
2013, 46, 2047-2058.
DOI: 10.1021/ar300309s
Copyright © 2013 American Chemical Society

Getting Distance Information
REDOR (rotational echo double resonance)
Gullion T, Schaefer J (1989) J Magn Reson 81:196
• Refocuses the effects of MAS on dipolar coupling
• Two 180 degree pulses every rotor period
• Get phase modulation due at magnitude of dipolar coupling
1 H
90x 180y
15 N
180y……. 180y……
 r
 r
 r
 r
 r
 r

Schaefer Laboratory, Washington University, St. Louis, MO

Distances can be extracted using REDOR-like mixing
(A) 2D 13C –13C CORD sequences: (1) basic CORD; (2) CORDxix; (3) CORDxy4. These irradiation schemes are composites of rotor-synchronized R2 nv -symmetry sequences, R211 (ωrf = ωr), R212 (ωrf = ωr), R221 (ωrf = 1/2 ωr), and R222 (ωrf = 1/2 ωr).
Each R2 nv element consists of two π pulses per n rotor periods. (B) 2D 13C –13C CORDxy4 spectra of U–13C,15N-LC8 (ωr =
40 kHz). Polarization transfer is uniformly efficient in both aliphatic and carbonyl regions of the spectrum.(11) Thioredoxin
Published in: Si Yan; Christopher L. Suiter; Guangjin Hou; Huilan Zhang; Tatyana Polenova; Acc. Chem. Res.
2013, 46, 2047-2058.
DOI: 10.1021/ar300309s
Copyright © 2013 American Chemical Society

Angular dependence of dipolar interaction vectors
Separated local field spectra (PISEMA)
15 N chemical shift
Gopinath, T.; Mote, KR.; Veglia, G (2013)
Sarcolipin in an oriented bicelle

Annual Reviews
2D solid-state NMR spectra of uniformly 15 N, 13 Clabeled Aβ
1-40 amyloid fibrils. ( a ) 2D 13 C13 C NMR spectrum, obtained in a 14.1-T magnetic field with 13.6-kHz magic-angle spinning, using a
2.94-ms finite-pulse radiofrequency-driven recoupling
(fpRFDR) sequence for spin polarization transfer in the mixing period. ( b ) 2D 15 N13 C spectrum, obtained with frequency-selective
15 N13 C cross-polarization followed by fpRFDR in the mixing period.

GPCR (CXCR1) structure in phospholipid bilayers
Park, ….Opella, SJ., Nature 491:779 (2012)

SOLIDS NMR REFERENCES
Opella, S.J. (2013) Structure Determination of Membrane Proteins by NMR
Spectroscopy Annual Rev. Anal. Chem, 6: 305-328.
Yan, S, Suiter, CL, Hou, G, Zhang, H and Polenova, T. (2013) Probing Structure and
Dynamics of Protein Assemblies by Magic Angle Spinning NMR Spectroscopy,
Accounts Chem. Research 46: 2047-2058.
Gopinath, T.; Mote, KR.; Veglia, G (2013) Sensitivity and resolution enhancement of oriented solid-state NMR: Application to membrane proteins, Prog. NMR
Spectroscopy 75: 50-68.
Solid-state NMR of matrix metalloproteinase 12: An approach complementary to solution NMR (2007) Balayssac S, Bertini I, Falber K, Oschkinat, H, et al.
CHEMBIOCHEM 8 486-489.
Solid-State NMR Studies of Amyloid Fibril Structure (2011) Tycko R. Ann. Rev. Phys.
Chem. 62, 279-299.
Recent contributions from solid-state NMR to membrane protein structure and function, Judge, PJ and Watts, A, (2011) Cur. Opin. Chem. Biol. 15, 690-695.