| Autor: |
Ko Y, Lin GM, Ruszczycky MW, Liu HW |
| Jazyk: |
angličtina |
| Zdroj: |
Biochemistry [Biochemistry] 2018 Jun 05; Vol. 57 (22), pp. 3130-3133. Date of Electronic Publication: 2018 Feb 28. |
| DOI: |
10.1021/acs.biochem.8b00110 |
| Abstrakt: |
DesII is a radical SAM lyase that catalyzes a deamination reaction during the biosynthesis of desosamine in Streptomyces venezuelae. Competing mechanistic hypotheses for this radical-mediated reaction are differentiated according to whether a 1,2-migration takes place and the timing of proton abstraction following generation of a substrate α-hydroxyalkyl radical intermediate. In this study, the deuterated C4 epimer of the natural substrate, TDP-4-amino-4-deoxy-d-[3- 2 H]fucose, was prepared and shown to be a substrate for DesII undergoing deamination alone with a specific activity that is only marginally reduced (∼3-fold) with respect to that of deamination of the natural substrate. Furthermore, pH titration of the deamination reaction implicates the presence of a hydron acceptor that facilitates catalysis but does not appear to be necessary. On the basis of these as well as previously reported results, a mechanism involving direct elimination of ammonium with concerted proton transfer to the nucleofuge from the adjacent α-hydroxyalkyl radical is proposed. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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