Pulse radiolysis studies of the reactions of nitrogen dioxide with the vitamin B12 complexes cob(II)alamin and nitrocobalamin.

We report kinetic studies on the reactions of NO2 with two forms of vitamin B12 - cob(II)alamin and nitrocobalamin. UV-visible spectroscopy and HPLC analysis of the product solution show that NO2 cleanly oxidizes the metal center of cob(II)alamin to form nitrocobalamin, with a second-order rate constant of (3.5±0.3)×10(8)M(-1)s(-1) (pH7.0 and 9.0, room temperature, I=0.20M). The stoichiometry of the reaction is 1:1. No reaction is detected by UV-visible spectroscopy and HPLC analysis of the product solution when nitrocobalamin is exposed to up to 2.0molequiv. NO2. PMID: 25450018 [PubMed - as supplied by publisher]
Source: Journal of Inorganic Biochemistry - Category: Biochemistry Authors: Tags: J Inorg Biochem Source Type: research