Nidhi Tiwari (Centre of Biomedical Research, India)
LinkedIn: Nidhi Tiwari, X: @TiwariNidhi05
Abstract: The speed of multidimensional NMR spectroscopy can be increased by an order of magnitude by shortening the recycle delay between scans. The consequent loss of longitudinal magnetization due to incomplete relaxation can be retrieved if undisturbed polarization is transferred from nearby proton spins not directly attached to 13C. In ASAP (Acceleration by Sharing Adjacent Polarization) HMQC, an ASAP block based on homonuclear Hartmann-Hahn mixing is incorporated, which consistently provides higher signal enhancement under identical total preparation time by transferring polarization from 12C attached (donor) protons to 13C attached (acceptor) protons, leading to repeated revival of detectable magnetization during short recovery delays.[1] Later on, this ASAP mechanism was also demonstrated to be useful for HSQC and NOAH (NMR by Ordered Acquisition using 1H detection); however, in HSQC, further improvement was achieved using the ZIP element, which overcomes the JHH (homonuclear ¹H-¹H J-evolution) modulation of the remote proton transverse magnetization by storing it before the start of the t1 evolution.
Recently, we have been addressing this JHH modulation in the HMQC class of experiments by combining the concept of ASAP and Perfect Echo-based refocusing of JHH in HMQC. This Perfect Echo-based ASAP-HMQC offers performance similar to that of ASAP-HSQC and better than that of only ASAP-HMQC.
Comparative analysis of ASAP-HMQC, ASAP-HSQC, and Perfect Echo ASAP-HMQC will be presented in the work.
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