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- Title
Mechanistic Studies of the Radical S-Adenosylmethionine Enzyme DesII with TDP- D-Fucose.
- Authors
Ko, Yeonjin; Ruszczycky, Mark W.; Choi, Sei ‐ Hyun; Liu, Hung ‐ wen
- Abstract
DesII is a radical S-adenosylmethionine (SAM) enzyme that catalyzes the C4-deamination of TDP-4-amino-4,6-dideoxyglucose through a C3 radical intermediate. However, if the C4 amino group is replaced with a hydroxy group (to give TDP-quinovose), the hydroxy group at C3 is oxidized to a ketone with no C4-dehydration. It is hypothesized that hyperconjugation between the C4 CN/O bond and the partially filled p orbital at C3 of the radical intermediate modulates the degree to which elimination competes with dehydrogenation. To investigate this hypothesis, the reaction of DesII with the C4-epimer of TDP-quinovose (TDP-fucose) was examined. The reaction primarily results in the formation of TDP-6-deoxygulose and likely regeneration of TDP-fucose. The remainder of the substrate radical partitions roughly equally between C3-dehydrogenation and C4-dehydration. Thus, changing the stereochemistry at C4 permits a more balanced competition between elimination and dehydrogenation.
- Subjects
ADENOSYLMETHIONINE; DEAMINATION; DEHYDROGENATION; HYPERCONJUGATION (Molecular physics); STEREOCHEMISTRY
- Publication
Angewandte Chemie, 2015, Vol 127, Issue 3, p874
- ISSN
0044-8249
- Publication type
Article
- DOI
10.1002/ange.201409540