2003 Fiscal Year Final Research Report Summary
The Metal Binding Motif of Dipeptidyl Peptidase III Influences the Enzyme Act ivity in the Copper Derivative of Dipeptidyl Peptidase III.
| Project/Area Number |
14572042
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Fukuyama University, Department of Applied Biological Science |
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Principal Investigator |
HIROSE Junzo Fukuyama Univ., Applied Biological Science, Professor, 生命工学部, 教授 (70080215)
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| Co-Investigator(Kenkyū-buntansha) |
FUKASAWA Kayoko Matumoto Dental Univ., 歯学部, 助教授 (60064698)
IWAMOTO Hiroyuki Fukuyama Univ., Applied Biologocal Science, 助教授 (90213321)
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| Project Period (FY) |
2002 – 2003
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| Keywords | zinc peptidase / zinc binding motif / dipeptidyl peptidase |
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| Research Abstract |
The zinc, binding motif (HELLGH) of dipeptidyl peptidase III (DPP III) is different from the common zinc binding motif (HExxH) of metallopeptidases. To clarify the importance of the zinc binding motif part (HELLGH) of DPP III for the enzyme activity, we measured the recovery of the enzyme activity of apo-Leu^<453> dipeptidyl peptidase III (apo-Leu^<453>-del-DPP III), which has a motif (HELGH) like that of the common peptidase (HExxH), in the presence of various metal ions. The enzyme activity of apo-Leu~<453> DPP III could not be recovered by the addition of cupric ions, while apo-DPP III could be easily reactivated by the addition of cupric ions. The visible and EPR spectra of the isolated Cu(II)-Leu^<453>-del DPP III clearly show that the cupric ions of Cu(II)-Leu^<453>-del-DPP III bound to the motif part (HELGH) but didn't exhibit any enzyme activity. The motif part of DPP III directly influences the expression of the enzyme activity in the copper derivative of DPP III. The competitive inhibitor that is not at all digested by DPP III, Hisprophen (His-Pro-Phe-His-Leu-d-Leu-Val-Tyr), have been found out. The inhibition constant (Ki) of Hisprophen for DPP III or Cu(II)-DPP III was 4. 1x10^<-5> 3.8xlO^<-5> M^<-1>, respectively. In the presence of the competitive peptide inhibitor, Hisprophen, the electron paramagnetic resonance (EPR) spectra of Cu(II)-DPP III were completely different from that of Cu(II)-DPP III itself. This result clearly indicates that the metal ions of DPP III locate in the active site and directly interact with the substrate.
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