| Project/Area Number |
09680660
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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 |
Biophysics
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| Research Institution | Kwansei Gakuin University |
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Principal Investigator |
SEGAWA Shin-ichi Kwansei Gakuin University, School of Science, Professor, 理学部, 教授 (70103132)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Cytochrome c / Peptide fragment-complex / Thermodynamics / Protein folding / Calorimetry / チトクロムC / ペプチド断片複合体 |
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| Research Abstract |
Two peptide fragments from tuna cytochrome c, (1-44)H [H means that the fragment contains heme] and (45-103), combine to from a 1 : 1 fragment complex. This was clearly proved by ion-spray mass spectrometry. CD and NMR spectra showed that the structure of the fragment complex formed is similar to that of on intact cytochrome c, although each isolated fragment itself is unstructured. Binding constants and enthalpies upon the complex formation were directly observed by isothermal titration calorimetry. The change in enthalpy upon the complex formation was somewhat larger than that upon protein folding, because of the electrostatic attractive interactions between the amino group of N-terminus of (45-103) and heme propionates. When the electrostatic force was reduced by the addition of KCI, the enthalpy change become to coincide with each other.
In addition, smaller peptide fragments were prepared to investigate the effect of the losing some peptide segment from the whole amino acid sequence of protein. Prepared peptide fragments were (1-21)H, (22-44), (45-66) and (67-103). Calorimetric and spectroscopic experiments showed that the peptide segment (45-66) is important for the formation of energetically stable structure between N- and C-terminal helices.
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