Kinetics and mechanism of oxidation of super-reduced cobalamin and cobinamide species by thiosulfate, sulfite and dithionite.
نویسندگان
چکیده
We studied the kinetics of reactions of cob(I)alamin and cob(I)inamide with thiosulfate, sulfite, and dithionite by UV-Visible (UV-Vis) and stopped-flow spectroscopy. We found that the two Co(I) species were oxidized by these sulfur-containing compounds to Co(II) forms: oxidation by excess thiosulfate leads to penta-coordinate complexes and oxidation by excess sulfite or dithionite leads to hexa-coordinate Co(II)-SO2(-) complexes. The net scheme involves transfer of three electrons in the case of oxidation by thiosulfate and one electron for oxidation by sulfite and dithionite. On the basis of kinetic data, the nature of the reactive oxidants was suggested, i.e., HS2O3(-) (for oxidation by thiosulfate), S2O5(2-), HSO3(-), and aquated SO2 (for oxidation by sulfite), and S2O4(2-) and SO2(-) (for oxidation by dithionite). No difference was observed in kinetics with cob(i)alamin or cob(i)inamide as reductants.
منابع مشابه
Electrocatalytic oxidation of sulfite Ion at the surface carbon ceramic modified electrode with prussian blue
The redox properties of sulfite ion has been examind using cyclic voltammetry in acetonitrile solvent at the surface of gold, pelatin and glassy carbon electrodes. It has bben found tha, sulfite ion exhibits two electron oxidation peak with EC’ mechanism. A novel chemically modified electrode containing Prussian blue complex and multi wall carbon nanotubes (MWCNs) was achieved on the surface of...
متن کاملIntramuscular cobinamide sulfite in a rabbit model of sublethal cyanide toxicity.
STUDY OBJECTIVE Exposure to cyanide in fires and industrial exposures and intentional cyanide poisoning by terrorists leading to mass casualties is an ongoing threat. Current treatments for cyanide poisoning must be administered intravenously, and no rapid treatment methods are available for mass casualty cyanide exposures. Cobinamide is a cobalamin (vitamin B(12)) analog with an extraordinaril...
متن کاملKinetics and Mechanism of Oxidation of n-Pentanol by Tetramethylammonium Fluorochromate
The oxidation of n-pentanol by tetramethylammonium fluorochromate in acidic solution wasstudied using spectrophotometric technique. The reaction was arranged to be under pseudo firstorderconditions respect to the oxidant. A Michaelis-Menten type kinetic was observed respect tothe substrate. The reaction is catalyzed by hydrogen ions. Dependences of the reaction rates ontemperature and different...
متن کاملMechanism of oxidation of inorganic sulfur compounds by thiosulfate-grown Thiobacillus thiooxidans.
Thiobacillus thiooxidans was grown at pH 5 on thiosulfate as an energy source, and the mechanism of oxidation of inorganic sulfur compounds was studied by the effect of inhibitors, stoichiometries of oxygen consumption and sulfur, sulfite, or tetrathionate accumulation, and cytochrome reduction by substrates. Both intact cells and cell-free extracts were used in the study. The results are consi...
متن کاملThiosulfate Oxidation and mixotrophic growth of Methylobacterium goesingense and Methylobacterium fujisawaense.
The mixotrophic growth with methanol plus thiosulfate was examined in nutrient-limited mixotrophic condition for Methylobacterium goesingense CBMB5 and Methylobacterium fujisawaense CBMB37. Thiosulfate oxidation increased the growth and protein yield in mixotrophic medium that contained 150 mM methanol and 20 mM sodium thiosulfate, at 144 h. Respirometric study revealed that thiosulfate was the...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Dalton transactions
دوره 42 43 شماره
صفحات -
تاریخ انتشار 2013