Visible Study Of Distribution Of Inorganic Mercury And Its Complex In Brain And Spinal Cord

The binding modes of Hg²⁺ by Glutathione (GSH) and L-cysteine (Cys) have been studied and the difference between them was investigated by means of carbon-13 magnetic resonance and Circular dichroism spectra. The ¹³C NMR and CD spectra all implied that the binding sites at the molar ratio of 1:2 to 2:3 Hg²⁺:Cys (GSH)—the sulfhydryl groups of Cys and GSH were still bound to Hg²⁺; in this span, not only the sulfhydryl group binds to Hg²⁺, but also the glutamyl end was involved in the binding of GSH to Hg²⁺. Surprisingly, the binding capacity of Hg²⁺ with Cys was powerful than that of GSH although more binding sites were available for GSH. In addition, the CD spectral envelope illustrated that the only one metal cluster was formed at Hg:GSH and Hg:Cys molar ratios of 1:5-1:2, and the 1:2 complex was the main species both for GSH-Hg²⁺ and Cys-Hg²⁺.The original Hg²⁺ fluorescence sensor EPNP, is developed to apply on cell biology, zoology and neurotoxicology. By fluorescent microscope, the study of mercuric ion in neurons and nerval tissue is high selectively and visibly achieved for the first time. So far, we have found the lowest injected dose and the shortest time that could be seen in the neurons and nerval tissue, that is 0.1μg/g body weight and three days. By contrast, no Hg²⁺ was observed in spinal cord neurons and spinal tissue sections. The differences of the mercuric ion between the neonatal mice and the adult mice may be resulted by the immature blood-brain barrier of the neotatal mice, which are different from those of the adult, render the brain of neonatal highly susceptible to insults from exposure to toxic metals.