Transverse optimization of spin relaxation in NMR

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

…

…

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