| Project/Area Number |
16390017
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical pharmacy
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| Research Institution | Kumamoto University |
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Principal Investigator |
YAMAGUCHI Yoshihiro Kumamoto University, Graduate School of Medical and Pharmaceutical Sciences, Instructor, 大学院・医学薬学研究部, 助手 (10363524)
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| Co-Investigator(Kenkyū-buntansha) |
KUROSAKI Hiromasa Kumamoto University, Graduate School of Medical and Pharmaceutical Sciences, Associate Professor, 大学院・医学薬学研究部, 助教授 (70234599)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥14,200,000 (Direct Cost: ¥14,200,000)
Fiscal Year 2005: ¥5,700,000 (Direct Cost: ¥5,700,000)
Fiscal Year 2004: ¥8,500,000 (Direct Cost: ¥8,500,000)
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| Keywords | hydrolase / β-lactam antibiotics / substrate-recognition mechanism / inhibitor / site-directed mutagenesis / x-ray crystallography / kinetics |
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| Research Abstract |
Metallo-β-lactamase (IMP-1) poses a potential threat for clinical environment because of wide spread substrate specificity and lack of the available inhibitors. IMP-1 requires two Zn(II) ions to hydrolyze β-lactam antibiotics.
To study the effects on Zn(II) binding to IMP-1, we examined the kinetics of dissociation of Zn(II) from wild type IMP-1. From the kinetic experiments, the dissociation of Zn(II) ion from IMP-1 appeared to be two steps. Apo IMP-1 was prepared by the addition of EDTA directly to wild type IMP-1 at 30 ℃. Up to the addition of Co(II) to apo IMP-1 in 1:1, the absorption bands due to d-d transitions appeared. Further addition of Co(II) to apo IMP-1 up to 2:1 resulted in the increases in absorption at 344 nm, due to LMCT from thiolate of Cys221 to Co(II), and d-d transitions. These result suggest that the binding of Co(II) to apo IMP-1 proceeds stepwise : a Co(II) ion initially binds to the Zn1 site and then the second Co(II) ion binds to the Zn2 site.
We prepared two inhibitors, pentafluorophenyl 3-mercaptopropionate (PFMP, 1) and 3-(3-mercaptopropionylsulfanyl)propionic acid pentafluorophenyl ester (MPAP, 2) for one of MBLs, IMP-1. From the gel-filtration experiment of the enzyme-inhibitor complex, these compounds inhibited IMP-1 irreversibly. Moreover, X-ray crystallography revealed that inhibitor 2 covalently binds to IMP-1 to form an amide bond between the amino group (N^ζ) of Lys224 and the inhibitor.
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