| Project/Area Number |
61480461
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
物質生物化学
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| Research Institution | Osaka University |
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Principal Investigator |
KOZO Hamaguchi Faculty of Science, Osaka University Professer, 理学部, 教授 (50001748)
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| Co-Investigator(Kenkyū-buntansha) |
YASUSHI Kawata Faculty of Science, Osaka University Sechnical staff, 理学部, 教務職員 (40177697)
後藤 祐児 大阪大学, 理学部, 助手 (40153770)
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| Project Period (FY) |
1986 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 1988: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥5,200,000 (Direct Cost: ¥5,200,000)
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| Keywords | pancreatic polypeptide / formation of alpha-helix / peptide fragment / polyprolin 2 type helix / helix-charge interaction / ヘリックスー電荷相互作用 / Pancreatic polypeptide / α-ヘリックス / ポリプロリン【II】型ヘリックス |
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| Research Abstract |
Some peptide fragments including the helical segment of chicken pancreatic polypeptide were prepared and their conformations were studied by circular dichroism.
PP7-36 (a peptide fragment corresponding to the sequence from 7 to 36 in chicken pancreatic polypeptide) showed a CD spectrum characteristic of the helix at pH 4.6 and at peptide concentrations as low as 1 muM. PP11-36 could form helical conformation only at high peptide concentrations and not at peptide concentrations lower than 10 muM. However, acetyl PP11-36 (the alpha-amino group of PP11-36 is acetylated so that no positive charge exists at the N-terminus) could form the helical conformation at pH 4.6 and the peptide concentrations where PP11-36 could not. Succinyl PP12-36 (the alpha-amino group of PP12-36 is succinylated to introduce a megative charge) could also form the helical conformation. The CD spectra of PP12-36 and PP13-36 were not characteristic of the helical conformation at all the pH values and all the peptide concentrations studied. Acetyl PP13-36, which has no charge at the N-terminus, could not form the helix. On the other hand, succinyl PP13-36, which has a negatie charge at the N-treminal end, could form the helix at pH 4.6. These findings indicated that the presence of the negative vharge of carboxylate at the N-terminal region of a peptide fragment is important for the helix formation.
On converting the carboxyl terminal amide group of succinyl PP13-36 to a carboxylate group, the resulting peptide could no longer form the helix. It was suggested that the presence of negative charge is unfavorble for the alpha-helix formation. The observations obtained here indicated that the interactions of a negative charge at the N-terminal region and of a positive charge at the c-terminal region with the helix dipole are important to stabilize the helix.
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