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Published August 1, 1978 | public
Journal Article

Studies of pH and Anion Complexation Effects on L-Arginine by Natural Abundance ^(15)N Nuclear Magnetic Resonance Spectroscopy

Abstract

Natural-abundance nitrogen-15 nuclear magnetic resonance (NMR) spectroscopy has been used to investigate (1) the effect of pH on the ^(15)N chemical shifts of L-arginine and (2) the possible effects on ^(15)N chemical shifts and T_1 values of the complexation of L-arginine with chloride ions, phosphate ions, and adenosine triphosphate (ATP) in aqueous solutions. Guanidine carbonate solutions and protamine sulfate solutions containing some of these ions have also been examined. On protonation of the guanidinium group of L-arginine, the guanidino nitrogens and the -NH- nitrogen show upfield shifts of 15 and 3 ppm, respectively, as a result of change in the second-order paramagnetic effect, while the a-amino nitrogen shows an 8-ppm downfield shift on protonation as a result of decreased shielding. Complexation with equimolar phosphate ions produces a small downfield shift of approximately 0.8 ppm in the chemical shift of the guanidino nitrogens of L-arginine. No significant changes in ^(15)N shifts or T_1 values were observed on complexation with chloride ions or adenosine triphosphate.

Additional Information

© 1978 American Chemical Society. Received November 28, 1977. Supported by the National Institutes of Health, Public Health Service, Grant GM-11073 from the Division of General Medical Sciences, and by the National Science Foundation.

Additional details

Created:
August 19, 2023
Modified:
October 24, 2023