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Antimicrobial Agents and Chemotherapy, 09 1997, 1922-1925, Vol 41, No. 9
M Iten, H Mett, A Evans, JC Enyaru, R Brun and R Kaminsky
Ornithine decarboxylase (ODC), the target enzyme of D,L-alpha-
difluoromethylornithine (DFMO), was investigated in four DFMO-tolerant
Trypanosoma brucei rhodesiense isolates from East Africa and two DFMO-
susceptible T. b. gambiense isolates from West Africa. Neither drug uptake
nor inhibition of ODC activity by DFMO in cellular extracts differed in the
two trypanosome subspecies. However, the specific ODC activity of the
cellular extracts was three times as high in T. b. rhodesiense isolates as
in T. b. gambiense isolates. Furthermore, a significant difference in the
turnover rate of ODC was observed. The time required to induce a 50%
reduction of T. b. rhodesiense ODC activity under cycloheximide pressure
(tentative half-life) was about 4.3 h, whereas that required for T. b.
gambiense ODC was longer than 18 h. We concluded that the higher specific
ODC activity and faster enzyme turnover contributed to a substantial degree
to the DFMO tolerance observed in the East African T. b. rhodesiense
isolates.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Alterations in ornithine decarboxylase characteristics account for tolerance of Trypanosoma brucei rhodesiense to D,L-alpha- difluoromethylornithine
Swiss Tropical Institute, Basel.
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