Development of novel therapeutic agents against African sleeping sickness targeted for GMP reductase.

2015 Fiscal Year Final Research Report

• Project/Area Number: 25660231
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Veterinary medical science
• Research Institution: Osaka Prefecture University
• Principal Investigator: Inui Takashi 大阪府立大学, 生命環境科学研究科(系), 教授 (80352912)
• Co-Investigator(Kenkyū-buntansha): ISHIBASHI Osamu 大阪府立大学, 生命環境科学研究科, 准教授 (70293214) ; NISHIMURA Shigenori 大阪府立大学, 生命環境科学研究科, 助教 (90244665)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 人獣共通感染症 / 寄生虫 / 核酸合成系酵素 / 酵素反応速度論的解析 / 医薬候補化合物 / X線結晶構造解析

Outline of Final Research Achievements

We characterized the steady-state kinetics of Trypanosoma brucei (T. brucei) GMP reductase (TbGMPR). TbGMPR but no enzymes of the host mammals was inhibited in the presence of a purine nucleotide analog ribavirin 5’-monophosphate (RMP) with a Ki value of 4.46 μM. RMP and its precursor ribavirin showed anti-parasitic effect on bloodstream forms of T. brucei in culture, and the IC50 of each compound was ranged around 25 μM. We further prepared a mutant enzyme (TbGMPR-d) lacking cystathionine β-synthase domain, which is absent in mammalian GMPRs, to determine its structure by X-ray crystallography. The structure of TbGMPR-d was resolved at 2.36Å and found to have a TIM barrel structure commonly observed in GMPRs of other organisms. However, in quaternary structure, TbGMPR-d showed a different subunit orientation as compared to that of human GMPR2. The enzyme assay revealed that the activity of TbGMPR-d was apparently lowered than the wild-type enzyme.

Free Research Field

酵素化学・構造生物学・薬理学