Adduct of Aquacobalamin with Hydrogen Peroxide

Abstract

Aquacobalamin binds hydrogen peroxide reversibly to form a cobalt­(III) hydroperoxo adduct with a 0.25 mM dissociation constant, as evidenced by UV–vis absorption spectroscopy and corroborated by NMR, Raman spectroscopy, stopped-flow UV–vis measurements, and density functional theory calculations.

Mechanistic Study for the Reaction of B12 Complexes with m-Chloroperbenzoic Acid in Catalytic Alkane Oxidations

“…It may support the easy access to the Co­(III) state of the B 12 complex under air in the presence of the axial ligand. Recently, Silaghi-Dumitrescu and co-workers reported the UV–vis spectrum of the cobalamin–H 2 O 2 adduct with the Co­(III) oxidation state and it showed a UV–vis spectrum similar to ours . Therefore, the Co­(III)– m CPBA adduct (acylperoxido complex, 19 Co(III) ) should be formed by the reaction of Cat Co(II) with m CPBA under air via 18 Co(II) as shown in Scheme a.…”

“…Recently, Silaghi-Dumitrescu and co-workers reported the UV−vis spectrum of the cobalamin− H 2 O 2 adduct with the Co(III) oxidation state and it showed a UV−vis spectrum similar to ours. 45 Therefore, the Co(III)− mCPBA adduct (acylperoxido complex, 19 Co(III) ) should be formed by the reaction of Cat Co(II) with mCPBA under air via 18 Co(II) as shown in Scheme 2a. The reaction of Cat Co(III) with mCPBA provided the same species, 19 Co(III) , judging from the UV−vis spectral change as shown in Scheme 2b (Figure 4c).…”

Cobinamide is a strong and versatile antioxidant that overcomes oxidative stress in cells, flies, and diabetic mice

“…We wanted to compare cobinamide to similar agents, and chose cobalamin, imisopasem, and MnTBAP for the following reasons. Cobalamin is structurally similar to cobinamide, cobalamin(II) reacts readily with O 2 · − and ONOO − , both cobalamin(II) and cobalamin(III) react with hydrogen peroxide, and cobalamin has antioxidant effects in several in-vivo systems [Table 1 ; ( 13 , 14 , 17 , 19–21 )]. Imisopasem and MnTBAP are SOD mimetics, with imisopasem having a relatively high reaction rate with O 2 · − , and MnTBAP additionally reacts with ONOO − ; both agents have been used extensively in cells and animals ( 24–32 ) (Table 1 ).…”

Versatile enzymology and heterogeneous phenotypes in cobalamin complementation type C disease

“…The pseudo-pentacoordinated cob(I)alamin transition state is more thermodynamically favorable than a tetracoordinated cob(I)alamin ( Kumar et al., 2012 ; Kumar and Kozlowski, 2011 ). Trends in the redox transformation of cobalamins have been extensively studied and reviewed elsewhere ( Butler and Kräutler, 2006 ; Dereven’kov et al., 2016 ; Johns et al., 2015 ; Lehene et al., 2021 ; Lexa and Saveant, 1976 ; Pugina et al., 2018 ; Salnikov et al., 2021 ).…”