CON(CA)CX

Experiment Details

Dimensions = 3

Isotope labeling required = ¹³C and ¹⁵N

Magnetization transfer = ¹H¹³CO-CP, ¹³CO¹⁵N-CP, ¹⁵N¹³Ca-CP, and finally Spin-Diffusion

Pulse program: hCONCaCX3D.tcp

Parameters:

p1 : C 90 at pl1

p2 : C 180 at pl1

p3 : H 90 at pl2

p15 : HC CP at sp41 (f1,C) and sp40 (f2,H)

p16 : NCa CP at pl5 (f3,N), sp50 (f1,C), pl33 (f2,H)

p17 : NCO CP at pl6 (f3,N), sp51 (f1,C), pl34 (f2,H)

p21 : N 90 at pl21

p22 : N 180 at pl21

pl1 : C pulse power

pl2 : H pulse power

pl5 : N NCa CP power

pl6 : N NCO CP power

pl12 : H dec power

pl14 : H DARR power (= 1*cnst31 (MAS freq); for PDSD = 0 W)

pl21 : N pulse power

pl33 : H dec power during NCa CP

pl34 : H dec power during NCO CP

sp40 : H CP power

sp41 : C CP power

sp50 : C NCa CP power

sp51 : C NCO CP power

d0 : incremented delay (t1))

d1 : recycle delay; 1 to 5 times T1

d8 : PDSD/DARR mixing time

d10 : incremented delay (t2)

d29 : extra time for constant duty cycle (t2)

d30 : extra time for constant duty cycle (t1)

pcpd2 : H dec pulse cpdprg2

cpdprg2 : Decoupling file cw, tppm (at pl12)

spnam40 : H ramp use e.g. ramp.10070 for variable amplitude CP

spnam41 : C ramp use e.g. square.100 for square pulse CP

spnam50 : CA ramp use e.g. tcn for amplitude modulated tangential pulse CP

spnam51 : CO ramp use e.g. tcn for amplitude modulated tangential pulse CP

cnst10 : Frequency reset to Carrier (o1, usually ~100 ppm)

cnst21 : Frequency offset for CO (~175 ppm)

cnst22 : Frequency offset for CA (~55 ppm)

cnst29 : expected td2 for use in constant duty cycle (-DCDC)

cnst30 : expected td1 for use in constant duty cycle (-DCDC)

cnst31 : MAS rotation rate in Hz

inf1: 1/SW(CO) = 2 * DW(CO)

inf2: 1/SW(N) = 2 * DW(N)

in0 : = inf1

in10: = inf2

in29: = inf2

in30: = inf1

l0 : loopcounter for F1

l1 : loopcounter for mixing time

l10: loopcounter for F2

ZGOPTNS : -DCDC : for constant duty cycle (parmode must equal DIM)

-DnoMix : to eliminate COCx mixing or blank

FnMODE: TPPI, States or States-TPPI

ns: MIN. 4 (full:16)

Comment on key optimization:

CON transfer typically requires some optimization based on NCO condition)

cnst22 = '55'; cnst21 = '175; p2 = 2*p1; p22 = 2*p21;

CNST31 = wr;PLW14 = PLW12 found in DARR optimization

parmode = 3D; o1p = '100'; o2p = '3'; o3p = '115'; ZGOPTNS = '-DCDC' for constant duty cycle

Example spectrum of GB1: The spectrum recorded at MAS @ 17587 Hz, with a 3.2 mm rotor.

References:

1. Solid-state NMR study of proteorhodopsin in the lipid environment: Secondary structure and dynamics. 2009