An ab initio study of the guanidinium fragments in tetrodotoxin and saxitoxin

SCF Hartree–Fock calculations are used to predict properties of the guanidinium fragment present in tetrodotoxin and saxitoxin, toxins known to block the sodium channels of the nerve cell membrane. The results, in terms of net atomic charges and geometries, are compared to similar calculation results obtained for the Na⁺–H₂O complex.