Related Experiment Video
Updated: Aug 14, 2026

Modification and Functionalization of the Guanidine Group by Tailor-made Precursors
Published on: April 27, 2017
An ab initio study of the guanidinium groups in saxitoxin
Anne-Marie Sapse1, Robert Rothchild, Kyu Rhee
1John Jay College and Graduate Center of the City, University of New York, 445 W 59th St, New York, NY 10019, USA. acransg6@aol.com
Abstract:
Quantum chemical (Hartree-Fock) calculations were performed on neutral and protonated saxitoxin in order to obtain optimum geometries, rotational energy barriers for the guanidinium ions and proton affinities. For comparison purposes, as model compounds, guanidinium systems in five and six membered rings were also investigated. In addition, DFT (B3LYP) calculations with the 6-31G** basis set were performed and the sodium affinities of the guanidinium groups in saxitoxin were obtained. It was concluded that the inhibition of the sodium channels by the saxitoxin is due to the interaction of the guanidinium group with carboxylate groups from the wall of the channel and not to the binding of the sodium ions.
Related Concept Videos
Activation and Inactivation of G Proteins
Physical Properties of Amines
Structure of Amines
Globular and Fibrous Proteins
Globular proteins are also known as spheroproteins and typically are approximately round in shape. They contain a mix of amino acid types and contain differing sequences in their primary structures. Globular proteins have many different functions, such as enzymes, cellular messengers, and molecular transporters. These roles often require the proteins to be...
GTPases and their Regulation
Large G-proteins, also known...
Chirality at Nitrogen, Phosphorus, and Sulfur
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...

