title: Broadband homonuclear TOCSY with amplitude and phase-modulated RF mixing schemes.
abstract: We have explored the design of broadband scalar coupling mediated (13)C-(13)C and cross-relaxation suppressed (1)H-(1)H TOCSY sequences employing phase/amplitude modulated inversion pulses. Considering a variety of supercycles, pulsewidths and a RF field strength of 10 kHz, the Fourier coefficients defining the amplitude and phase modulation profiles of the 180 degrees pulses were optimised numerically so as to obtain efficient magnetisation transfer within the desired range of resonance offsets. The coherence transfer characteristics of the mixing schemes were assessed via numerical simulations and experimental measurements and were compared with commonly used sequences based on rectangular RF pulses. The efficacies of the clean (1)H-(1)H TOCSY sequences were also examined via numerical simulations for application to weakly oriented systems and sequences with efficient, broadband and clean dipolar transfer characteristics were identified. In general, the amplitude and phase modulated TOCSY sequences presented here have moderately better performance characteristics than the sequences currently employed in biomolecular NMR spectroscopy.
authors.affiliation: Research Group Biomolecular NMR spectroscopy, Leibniz Institute for Age Research, Fritz Lipmann Institute, 07745, Jena, Germany.
authors.forename: Anika
authors.initials: A
authors.lastname: Kirschstein
authors.forename: Christian
authors.initials: C
authors.lastname: Herbst
authors.forename: Kerstin
authors.initials: K
authors.lastname: Riedel
authors.forename: Michela
authors.initials: M
authors.lastname: Carella
authors.forename: Jörg
authors.initials: J
authors.lastname: Leppert
authors.forename: Oliver
authors.initials: O
authors.lastname: Ohlenschläger
authors.forename: Matthias
authors.initials: M
authors.lastname: Görlach
authors.forename: Ramadurai
authors.initials: R
authors.lastname: Ramachandran
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry; D003903:Deuterium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015203:Reproducibility of Results
chemical_list: D002247:Carbon Isotopes; D003903:Deuterium