Two-dimensional 1H NMR spectroscopy of aqueous solutions with elimination of the water resonance by transverse relaxation: Application to assignment of the 1H NMR spectrum of reduced arginine vasopressin

✍ Scribed by Cynthia K. Larive; Dallas L. Rabenstein

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 560 KB
• Volume: 29
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260290502

✦ Synopsis

The measurement of two-dimensional COSY and TOCSY '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 9 0 ' 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 :or the reduced, dithiol form of arginine vasopressin in H,O-D,O (90: 10) solution. These spectra, together with onedimensional spectra and tw+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 'H NMR spectrum of reduced arginine vasopressin. Elimination of the water resonance is sufficiently complete and selective that the resonance for the a-proton of the cys6 residue, which has a chemical shift of 4.758 ppm, is observed without interference from the water resonance. Chemical shift and J(NH, H a ) data are also presented for native arginine vasopressin under the same solution conditions.