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核磁共振光譜與影像導論. Introduction to NMR Spectroscopy and Imaging Lecture 06 Nuclear Overhauser Effect (NOE) and NOESY (Spring Term, 2011) Department of Chemistry National Sun Yat-sen University. Nuclear Overhauser Effect (NOE) and NOESY. Population Transfer.

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slide1

核磁共振光譜與影像導論

Introduction to NMR Spectroscopy and ImagingLecture06Nuclear Overhauser Effect (NOE) and NOESY(Spring Term, 2011)Department of ChemistryNational Sun Yat-sen University

population transfer
Population Transfer

In population manipulations, the most commonly used technique is

selective population transfer (SPT):

nuclear overhauser effect noe

N

N

S

S

Nuclear Overhauser Effect (NOE)

r

The distance between the two spins therefore can be determined by disturbing

one of them and observing how other is affected.

nucleus electron oe mechanism

=422+422=844

99

98

547

=1+5=6

520

100

550

W2

W0

547

995

577

999

1000

550

Nucleus-Electron OE: Mechanism

W2>>W0

nucleus electron oe mechanism1

99

=-410-410=-820

547

517

=1+5=6

100

107

550

W2

W0

547

995

990

1000

580

550

Nucleus-Electron OE: Mechanism

W2<<W0

nucleus nucleus oe nuclear oe noe mechanism

=32+32=64

18

24

54

=2+10=12

56

20

60

W2

W0

54

90

58

90

100

60

Nucleus-Nucleus OE (Nuclear OENOE): Mechanism

W2>>W0

nucleus nucleus noe mechanism

=-26-26=-52

18

50

54

=2+10=12

24

20

60

W2

W0

54

90

90

64

100

60

Nucleus-Nucleus NOE: Mechanism

W2<<W0

slide12

Whenever a polarization or a transition of a spin is inverted or saturated, the polarization or transition of the other spins that are coupled to it will be affected.

Perturbation on a Spin (Saturation/Inversion) + Cross Relaxation

The Polarization of Another (Coupled) Spin Is Altered.

Depending on the relative magnitudes of W2 and W0, NOE factor can be

Larger or smaller than 1 and can be both negative and positive.

slide13

w2

w0

longitudinal relaxation rates also affect noe

=15+15=30

18

19

54

=2+10=12

34

20

60

W2

W0

54

90

80

95

100

60

Longitudinal Relaxation RatesAlso Affect NOE

R1S

R1I

R1S

W2,W0, R1I, R1S all affect overall NOE.

Here W2 > W0, R1I, R1S

Positive NOE

longitudinal relaxation rates also affect noe1

=6+6=12

18

18

54

=2+10=12

24

20

60

W2

W0

54

90

90

96

100

60

Longitudinal Relaxation RatesAlso Affect NOE

R1S

R1I

R1S

W2,W0, R1I, R1S all affect overall NOE.

Here W2 > W0, R1I, but R1S>W2.

No NOE

longitudinal relaxation rates also affect noe2

=3-3=0!

18

19

54

=2+10=12

22

20

60

W2

W0

R1S

54

90

95

92

R1I

100

60

R1S

Longitudinal Relaxation RatesAlso Affect NOE

W2,W0, R1I, R1S all affect overall NOE.

Here W0> W2, but R1I>W0, R1S

Negative NOE

relaxation rates and motion

W0

logW

W2

W1

4

2

-4

-3

-2

-1

0

1

3

Relaxation Rates and Motion

Fast motion

Slow motion

For slow motions,

W0 is dominant

and NOE tends to

negative.

homonuclear steady state noe

=12+12=24

18

24

54

=2+10=12

36

20

60

W2

W0

54

90

78

90

100

60

Homonuclear Steady State NOE

NOE factor depends on W2, W0

slide28

Red: Saturated peak

Black: NOE affected peak

1d homonuclear transient noe

85

90

81

R1

R1

90

W2

100

90

88

W0

81

90

R1

98

90

100

1D Homonuclear Transient NOE

180o

A single spin is inverted and the spin system response is

read using a 90° pulse after a “mixing” time delay of variable duration. In the transient mode, the NOE builds up due to cross-relaxation of nearby spins by the inverted spin as the entire spin system.

Neither have to be steady

Nor have to be equilibrium

noe essence

N

N

S

S

NOE: Essence

Whenever the polarization of one of two coupled spins deviates from its equilibrium value, the polarization of the other spin is affected by cross relaxations. The NOE factor (the extent that the polarization of the unperturbed spin is affected) depends on cross relaxation rates and longitudinal relaxation rates.

r

slide34

A

B

When the distance between spins A and B is smaller than ~ 5 Å, NOE

cross peaks are observable.

slide38

3

6

7

8

10

9

4

5

2

1

3

1

2

6

10

5

8

7 4

9

slide39

3

6

7

8

10

9

4

5

2

1

3

1

2

6

10

5

8

7 4

9

1d homonucelar roe

180o

90o

1D Homonucelar ROE

A single transition is inverted using a selective 180° pulse (along the x axis), and

then a hard 90° x pulse is immediately applied to the spin system.

This has the effect of placing the “inverted” magnetization along the -y axis while

the rest of the magnetization is aligned along +y. Then, a low-power rectangular

pulse is applied long the y-axis.

This pulse is applied parallel to the magnetization (in the rotating frame) and effects

no net rotation. Instead, it “locks” the magnetization along the y axis, and is referred

to as a spin lock pulse. The magnetization is said to be spin locked because

it doesn’t precess about B0, but the spins now precess aboutB1(the spin lock pulse).

Therefore, under these conditions, the magnetization can be considered to being

analogous to alignment along the z axis in the presence of B0 alone.

Finally, the spins will relax towards a new equilibrium in the presence of B1;

the characteristic time constant for this decay is called T1ρ forT1in the rotation frame.

roe mechanism all relaxation rates are changed into rotating frame

Y

81

R1rho

R1rho

W2rho

100

W0,rho

90

R1rho

90

76

81

92

90

95

90

98

100

ROE Mechanism:All relaxation rates are changed into rotating frame.

Z

Rotating frame

Note that both W2 and W0 promote ROE!

slide44

For homonuclear systems

W2 promotes NOE while W0

blocks NOE

Both W2 and W0 promote ROE

some applications of noesy
Some Applications of NOESY

Sterochemistry

Polymers

Hydration of biomolecules

Structure determination of biomacromolecules

corma
CORMA

CORMA(COmpleteRelaxationMatrixAnalysis)

Principle of CORMA

Example of CORMA

slide64

CORMA

V(τm)=V0 exp(Rτm)

slide66

Detection of hydration water via observation of NOEs from water-protein

--- G. Otting, E. Liepinsh, K. Wuthrich, Science1991,254,974

BPTI 牛胰蛋白抑制劑

Residues : 58

Internal water : 4

Residence times:

Interior water:10-2-10-8s

Surface water:10-9s

slide67

Assignments of water-solute cross peak :

  • Direct water-solute NOE
  • (hydration water-solute)
  • (b) Exchange-relayed NOE
  • (solute-solute)
  • (c) Chemical exchange
  • (bulk water-solute)

Non-labile

Labile

Labile

--- G. Otting,J. Progr. NMR. Spectrosc. 1997, 31 , 259

slide68

2

5

3

6

4

Glu1-190 ( mix=0.4 ms )

significance to structure determination
Significance to Structure Determination

A

B

C

rij=(1.78 Å)×(σkl/σij)1/6

D

Intensity:640

Distance:1.78Å

Intensity:10

Distance:3.56Å

E

F

slide71

i+1

i

COSY

NOESY

NOESY

NOESY

i COSY

(i+1) COSY

NH-CαH

(i+1)NH-CαH

iCαH-(i+1)NH

COSY

CTX II: 44-60