Concerning the intermediacy of organic radicals in vitamin B12-dependent enzymic reactions
- 17 December 1985
- journal article
- Published by The Royal Society in Philosophical Transactions of the Royal Society of London. B, Biological Sciences
- Vol. 311 (1152), 531-544
- https://doi.org/10.1098/rstb.1985.0162
Abstract
The vitamin B12coenzyme adenosylcobalamin assists the enzymic catalysis of molecular rearrangements of the type in which the migrating group X can be OH, NH2or a suitable substituted carbon atom such as C (=CH2)CO2H. This paper discusses evidence for the participation of organic radicals as intermediates in these reactions. Theoretical and model studies supporting the intermediacy of radicals in the reactions catalysed by the enzymes diol dehydratase and α-methyleneglutarate mutase are described. For the model studies, alkyl radicals, alkylcobaloximes (alkyl represents, for example, ethoxycarbonyl substituted, but-3-enyl and cyclopropylmethyl) and also dihydroxyalkylcobalamins have been investigated. The Co-Cα-Cβangle of 125° in adenosylcobalamin is shown to be an ‘especial’ angle by analysis of the crystal structures ofR- andS-2,3-dihydroxypropylcobalamin.Keywords
This publication has 19 references indexed in Scilit:
- The crystal structures of (R)- and (S)-2,3-dihydroxypropylcobalamin; comparison with the structure of adenosylcobalaminJournal of the Chemical Society, Chemical Communications, 1985
- Synthesis and rearrangements of ethoxycarbonyl-substituted but-3-enyl- and cyclopropylmethyl-(pyridine)cobaloximesJournal of the Chemical Society, Chemical Communications, 1983
- Coenzyme B12 model studies: an electrochemical comparison of both alkylcobaloxime and nonalkyl cobaloxime and Co[C2(DO)(DOH)pn] complexes to coenzyme B12Journal of the American Chemical Society, 1981
- Model experiments relevant to the mechanism of adenosylcobalamin-dependent diol dehydrase: further investigations of isomerisations of dihydroxyalkyl radicalsJournal of the Chemical Society, Perkin Transactions 2, 1980
- The vitamin B12 coenzymeAccounts of Chemical Research, 1976
- Carbon-skeleton rearrangement of the alkyl ligand in a vitamin B12 derivativeJournal of the Chemical Society, Chemical Communications, 1976
- Conversion of 1,2‐Diols into Aldehydes Induced by Photolysis of Alkylcobaloximes: A Model System for DioldehydraseAngewandte Chemie-International Edition, 1975
- Facilitation of intramolecular 1,2-shifts in radicals by protonation, and the mechanism of reactions catalysed by 5′-deoxyadenosylcobalaminJournal of the Chemical Society, Chemical Communications, 1973
- Solvolysis of σ‐2‐Acetoxyalkylbis(biacetyldioximato)pyridinecobalt: Evidence for a Novel Intermediate Olefinic ComplexAngewandte Chemie-International Edition, 1970
- ON THE MECHANISM OF THE COBAMIDE COENZYME DEPENDENT ISOMERIZATION OF METHYLMALONYL COA TO SUCCINYL CoAJournal of the American Chemical Society, 1960