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Published April 18, 2001 | metadata_only
Journal Article

Salt Bridge Stabilization of Charged Zwitterionic Arginine Aggregates in the Gas Phase


The discovery of several new unusually stable aggregates of arginine that are intermolecularly bound by salt bridges is reported. Quadrupole ion-trap mass spectrometry provides evidence for the stability of arginine in the zwitterionic state, where the protonated guanidinium group of one arginine interacts strongly with the carboxylate of another to form stable noncovalent complexes, coordinated to either a cation or anion. Clusters of arginine with itself, sodium, potassium, lithium, magnesium, chloride, fluoride, bromide, iodide, and nitrate are observed. DFT calculations at the B3LYP/6-31G** level are used to assess the structures and energetics of particularly prominent clusters. An examination of mixtures of d-arginine with isotopically labeled l-arginine indicates that the stability of these clusters does not depend on arginine enantiomeric purity. The cyclic trimers of arginine, capped with either Cl^- or NO_3^-, possess exceptional stability.

Additional Information

© 2001 American Chemical Society. Received 21 August 2000. Published online 21 March 2001. Published in print 1 April 2001. We thank Sang-Won Lee for helpful suggestions in performing the calculations and Heather Cox for assistance in using the LCQ mass spectrometer. Funding was provided by the NSF (Grant CHE-9727566) and the Beckman Institute. The LCQ mass spectrometer was funded by an instrumentation grant from NSF.

Additional details

August 19, 2023
August 19, 2023