Ornithine decarboxylase (ODC) is under cell cycle control and increased ODC activity has been linked to both neoplasm and viral infection. ODC is an effective pharmacological target for the treatment of infections by Trypanosoma brucei. Remarkably, the mechanism of catalysis by ODC has not been clearly demonstrated nor is a structure known.
The specific aims of the proposed experiments are: (I) The mechanism of catalysis by ODC will be established as follows: (I.A) Mutagenesis will be utilized to stabilize or destabilize catalytic intermediates. (I.B) The reaction of orn with wild-type and mutant ODC's will be characterized using both CD and UV-visible stopped-flow spectroscopy. (I.C) The pH profile of mutant ODC's will be determined using both steady-state and stopped-flow techniques to correlate the rate constants for formation of individual chemical species with the chemistry of catalysis. (I.D) Solvent isotope effects will be used to help establish the mechanism of catalysis. (II) Two classes of mechanism-based ODC inhibitors will be synthesized and tested, (II.A) Bisubstrate analogs and (II.B) two potential suicide inhibitors.
| Jackson, L K; Brooks, H B; Osterman, A L et al. (2000) Altering the reaction specificity of eukaryotic ornithine decarboxylase. Biochemistry 39:11247-57 |
| Osterman, A L; Brooks, H B; Jackson, L et al. (1999) Lysine-69 plays a key role in catalysis by ornithine decarboxylase through acceleration of the Schiff base formation, decarboxylation, and product release steps. Biochemistry 38:11814-26 |
| Grishin, N V; Osterman, A L; Brooks, H B et al. (1999) X-ray structure of ornithine decarboxylase from Trypanosoma brucei: the native structure and the structure in complex with alpha-difluoromethylornithine. Biochemistry 38:15174-84 |
| Swanson, T; Brooks, H B; Osterman, A L et al. (1998) Carbon-13 isotope effect studies of Trypanosoma brucei ornithine decarboxylase. Biochemistry 37:14943-7 |
| Brooks, H B; Phillips, M A (1997) Characterization of the reaction mechanism for Trypanosoma brucei ornithine decarboxylase by multiwavelength stopped-flow spectroscopy. Biochemistry 36:15147-55 |
