Spin-state diagramm and I /S correlation spectrum of a spin ½ IS spin system
Transverse Relaxation Optimized SpectroscopY
(TROSY)
Transverse Relaxation Optimized SpectroscopY
(TROSY)
Prof. K. Pervushin, BioNMR group , LPC, D-CHAB, ETH Zürich
An overview
Chemical shift correlations in protein backbone spin systems using TROSY: 120 kDa Aldolase
Spin-state diagramm and I /S correlation spectrum of a spin ½ IS spin system
- Relaxation effects in spin systems
- Construction of NMR experiments utilizing favorable relaxation properties
Evolution of density operator for static molecule
Hamiltonian representation as product of spherical harmonics and irreducible tensors of 2nd rank
Evolution of an ensemble of spins
Spin relaxation
DD/DD interference –reducing relaxation
DD/DD interference –enhancing relaxation
Chemical Shift Anisotropy (CSA) relaxation
HDD(I,S) = ISh/r3 [2IzSz – IxSx IySy]
HCS(I) = I [1IzHz + 2 (IxHx + IyHy)]
HCS(I) = 1/3I [(1+ 2 2)H*I+
(1-2) (2IzHz IxHx IyHy)]
DD/CSA interference –enhancing relaxation
DD/CSA interference –reducing relaxation
CSA/CSA interference –enhancing relaxation
CSA/CSA interference –reducing relaxation
TROSY effect as function of B0
- Relaxation effects in spin systems
- Construction of NMR experiments utilizing favorable relaxation properties
Spin-state diagramm and I /S correlation spectrum of a spin ½ IS spin system
Spin-state diagramm and I /S correlation spectrum of a spin ½ IS spin system
Fundamental bounds associated with polarization/coherence transfer imposed by qunatum spin dynamics
C
1. Maximum transfer bound,
U
2. Minimal spin-evolution time required for the transfer, min
3. Suppression of spurious transfers, Q
4. Combined use of more source operators, C
5. Complexity of pulse sequence
Computer-based design of NMR (near) optimal experiments
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…
Computer-based design of NMR (near) optimal experiments
Use of MD simulations in the space of pulse sequence variables for constructing of optimal NMR experiments
Statistics of computer-based design of Methyl TROSY experiments
= 1/J
Complexity versus efficiency of NMR experiments
= 1/J
…
…n
TROSY (ST2-PT) of Pervushin et al. is theoretically optimal (!!!)
= 1/J (minimal)
b/bmax=100%
n =2
Source: 1H+15N
No spurious transfers
TROSY of Kay et al. is theoretically optimal
= 1/J (minimal)
b/bmax=100%
n =2
Source: 1H+15N
No spurious transfers
ZQ-TROSY of Pervushin et al. is theoretically optimal
= 0.5/J (minimal)
b/bmax=100%
n =1
Source: 1H+15N
No spurious transfers
1H-15N RDCs measurements with COCAIN TROSY
Time-, magnetization source- and transfer efficiency-optimal CoCaIn experiment: theoretically optimal pulse sequence
IzS 1/2 I(E + 2Sz) = 1/2I
IzS 1/2I (E 2Sz) = 1/2I
= 0.5/J (minimal)
b/bmax=100%
n =1
Source: 1H+15N
No spurious transfers
Time-, magnetization source- and transfer efficiency-optimal CoCaIn experiment: Spectra
RDCs in methyl groups1313CC++
11HHxx -> -> 11HH11HH
Construction of optimal NMR experiments
Measurements of 1H-1H RDCs in methyl groups
-Relaxation effects in spin systems
- Construction of NMR experiments utilizing favorable relaxation properties
- NMR with very large molecules: optimal polarization transfer plus TROSY
The primate erythrocyte/immune complex clearing mechanism
Human complement receptor type 1 (CR1)
INEPT-based HSQC of 220 kDa CR1/C3b complex
2 (1H) [ppm]
1 (15N) [ppm]
Differential driving of the manifolds Iand I by
selective rf-pulse
Iz = Iz+ I z → Iz
I z = 2Iz Sz
Ii= Ii(1/2E +Sz)
Ii= Ii(1/2E Sz) Iz
I z
Excitation profile of polychomatic pulse
Polychomatic pulse wave-form and spin trajectory
Polarization transfer using polychromatic irradiation
2 (1H) [ppm]
1 (15N) [ppm]
CRINEPTPOLY-C
PC-SPI spectra of free CR1 and CR1/C3b complex
CR1/C3b complex
CR122 kDa
CR1/C3b complex220 kDa