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Two‐dimensional 1 H NMR spectroscopy of aqueous solutions with elimination of the water resonance by transverse relaxation: Application to assignment of the 1 H NMR spectrum of reduced arginine vasopressin
Author(s) -
Larive Cynthia K.,
Rabenstein Dallas L.
Publication year - 1991
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260290502
Subject(s) - chemistry , resonance (particle physics) , pulse sequence , spectral line , relaxation (psychology) , nmr spectra database , aqueous solution , analytical chemistry (journal) , nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , spectroscopy , stereochemistry , atomic physics , chromatography , physics , psychology , social psychology , astronomy , quantum mechanics
The measurement of two‐dimensional COSY and TOCSY 1 H NMR spectra of aqueous solutions with elimination of the water resonance by the water attenuation by transverse relaxation (WATR) method is described. With the WATR method the water resonance can be completely and selectively eliminated, allowing observation of resonances that would normally be obscured by the water resonance or eliminated if the water resonance is suppressed by selective presaturation. COSY spectra are measured by a modified COSY pulse sequence, with a delay between the second 90° pulse of the standard COSY pulse sequence and data acquisition to eliminate the water resonance by transverse relaxation. TOCSY spectra are measured using a modified TOCSY pulse sequence which includes a delay for transverse relaxation immediately following the 90° pulse. The effectiveness of the WATR method for elimination of the water resonance from COSY and TOCSY spectra is illustrated with spectra measured for the reduced, dithiol form of arginine vasopressin in H 2 OD 2 O (90:10) solution. These spectra, together with one‐dimensional spectra and two‐dimensional ROESY spectra, also measured with elimination of the water resonance by the WATR method, are used to make the first complete assignment of the 1 H NMR spectrum of reduced arginine vasopressin. Elimination of the water resonance is sufficiently complete and selective that the resonance for the α‐proton of the cys 6 residue, which has a chemical shift of 4.758 ppm, is observed without interference from the water resonance. Chemical shift and J (NH, H‐α) data are also presented for native arginine vasopressin under the same solution conditions.