HZQC/HDQC for Bruker (hdqc Zex.rp)

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Basic facts about hdqc_Zex.rp

Synopsis: HZQC and HDQC pulse sequence - allows to measure kon and koff in slow chemial exchange process

Family: HZQC/HDQC

Code authors:

 Robert PetersonRobert Clubb, Scott RobsonValerie Villareal, Louis-S Bouchard

Copyright: UCLA, Clubb Lab

Introduction

HZQC and HDQC pulse sequences allow to measure rates of association and dissociation in molecular complexes, when chemical exchange is slow.

Please see HZQC/HDQC for more details.

Pulse sequence is switched between HZQC and HDQC by changing strengths of gradients gp4 and gp5 as described below.

General setup

  • ns - number of scans - multiple of 4, because phase cycle has four steps - [160]

Delays

  • d1 - recycling delay - [1s]
  • d16 - gradient recovery delay - [200μs] (hardware dependent)
  • d21 - 1H-15N INEPT delay when 1H is transverse - [2.25ms]
  • d22 - 1H-15N INEPT delay when 1H is transverse - [2.72ms]

Constants

  • L3 - loop counter for mixing time. The length of the Nz period = 10msec*L3 + 3.2msec. - [8]

RF channels

  • O1p - offset for 1H transmitter - on water resonance - [4.7]
  • O2p - offset for 13C transmitter - center of Cα region - [50]
  • O3p - offset for 15N transmitter - center of amide region - [115]

1H channel

  • p1 - length of hard 1H 90o pulse

sp1

  • p11 - length of sp1 pulse - [1.2ms]
  • sp1 - power level for sp1 pulse
  • pl11 - 120dB
  • spnam1 - waveforum for sp1 pulse - [Sinc1.1000]
  • phcor1 - phase correction for sp1 pulse - [0]

sp2

Selective 90o 1H pulse for water resonance.

  • p12 - length of pulse sp2 - [1.2ms]
  • sp2 - power level for sp2 pulse
  • pl12 - 120dB
  • spnam2 - waveform for sp2 - [Sinc1.1000]

sp4

Selective 180o 1H for amides, that does not perturb H2O.

  • p14 - length of pulse sp4. p14 should invert amide protons, but not excite water - [1.5ms]
  • sp4 - power level for sp4 pulse
  • pl14 - 120dB
  • spnam4 - waveform for sp4 pulse - [Ipurp2.1000]
  • spoffs4 - offset of pulse sp4 - center of amide region

sp3

  • p13 - length of pulse sp3 - [1ms]
  • sp3 - power level of sp3 pulse
  • pl13 - 120dB
  • spnam3 - waveform of pulse sp3 - [gauss]
  • phcor5 - phase correction for pulse sp3 - [95]

13C channel

  • p3 - hard 90o for 13C
  • pl2 - power level for 13C 90o

15N channel

  • p12 - hard 90o for 15N
  • pl3 - power level for hard 15N 90o pulse

15N decoupling

Broadband 15N decoupling is performed during acquisition.

  • pcpd3 - length of 90o pulse for waltz16 - [200]
  • pl16 - power level for the 90o pulse within the waltz16 decoupling
  • cpdprg3 - program for composite pulse decoupling - [waltz16]

Gradients

All gradients are of sine bell shape, i.e.spnamN is SINE.100, where N = [1...7]

In addition all gradients are along z axis, so all gpxN and gpyN should be zero.

Values of gradient strength are give in percent, assuming that 100% corresponds to about 50G/cm.

Related parameter is d16 - gradient recovery delay.

gp1

  • p16 - length of gradient gp1 - [1ms]
  • gpz1 - strength of Z gradient gp1 - [23]

gp2

Gradient gp2 is used for the echo-antiecho method of quadrature detection.

  • p17 - length of gradient gp2 - [0.5ms]
  • gpz2 - strength of gradient gp2 - [-35]

gp3

  • p20 - length of gradient gp3 - [2ms]
  • gpz3 - strength of gradient gp3 - [63]

gp4 and gp5

  • p18 - length of gradient gp4 - [0.5ms]
  • p19 - length of gradient gp5 - [1ms]

Image:18px-Bulbgraph.png Note: Gradients gp4 and gp5 are used to select type of coherence for the indirect dimension and switch the pulse sequence from HZQC to HDQC as shown below:

For HZQC option

  • gpz4 - strength of gradient gp4 - [62.9]
  • gpz5 - strength of gradieng gp5 - [62.9]

For HDQC option

  • gpz4 - strength of gradient gp4 - [77.1]
  • gpz5 - strength of gradieng gp5 - [77.1]
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