Organic/inorganic hybrid nanomaterials with vitamin B₁₂functions

Abstract

A hybrid nanomaterial was prepared by human serum albumin (HSA) and vitamin B 12 derivatives. The incorporation of hydrophobic vitamin B 12 derivatives, which have ester groups in place of the peripheral amide moieties of the natural cobalamin, into HSA is primarily controlled by the hydrophobicity of the peripheral ester groups. Microenvironmental property around the hydrophobic vitamin B 12 in HSA was examined by fluorescence and fluorescence polarization measurements. The hydrophobic vitamin B 12 itself in HSA is in a microenvironment equivalent in medium polarity to dichloromethane. The molecular motion of hydrophobic vitamin B 12 in HSA was markedly suppressed under such microenvironmental conditions. Carbon-skeleton rearrangement reaction of an alkyl radical derived from an alkyl ligand bound to the hydrophobic vitamin B 12 was markedly favored in HSA aqueous solution, relative to the reactions in methanol and benzene. The 1,2-migration of the electron-withdrawing group arises from both the suppression of molecular motion and desolvation effects on the alkylated hydrophobic vitamin B 12 in HSA. r

Bioinspired catalytic reactions with vitamin B12 derivative and photosensitizers

“…We used HSA as an apoenzyme model for construction of an artificial Brought to you by | University of Utah Authenticated Download Date | 10/6/14 2:41 PM B 12 enzyme. The incorporation of the hydrophobic vitamin B 12 derivatives into HSA is primarily controlled by the hydrophobicity of the peripheral ester groups [14]. We used the heptapropyl ester derivative as the hydrophobic vitamin B 12 .…”

Learning from B12 enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

“…Indeed, in the crystal structure, 1 maintained the same corrin framework as natural B 12 [ 31 ]. We combined the hydrophobic B 12 derivatives with bilayer vesicles [ 32 – 33 ], a protein [ 34 ], organic polymers [ 35 – 40 ], and metal organic frameworks (MOFs) [ 41 ]. Furthermore, to construct green catalytic systems inspired by B 12 enzymes, we combined the hydrophobic B 12 derivatives with a functional equivalent of reductases.…”

“…We developed another artificial enzyme composed of human serum albumin (HSA) and heptapropyl cobyrinate [ 34 ]. It is known that HSA acts as a carrier for in vivo hydrophobic molecules.…”

Cobalt tetradehydrocorrins coordinated by imidazolate-like histidine in the heme pocket of horseradish peroxidase

“…Furthermore, characteristic imidazolate-like histidine ligation to the cobalamin cofactor is observed in the abovementioned methionine synthase as well as in methylmalonyl-CoA mutase and glutamate mutase [16][17][18][19][20]. Over the past decades, several model systems have been reported using cobalamin and its derivatives as well as cobalt corrinoid complexes [20][21][22][23][24][25][26][27][28]. Previously, our group reported the structure, reactivity and physicochemical properties of myoglobin (Mb) reconstituted with Co(TDHC), (TDHC = 8,12-dicarboxyethyl-1,2,3,7,13,17,18,19-octamethyltetradehydrocorrin), rMb(Co(TDHC)), in efforts to develop a useful proteinbased model of cobalamin-dependent methionine synthase [29][30][31][32].…”