2003 Fiscal Year Final Research Report Summary
First-principles theory of the protein nanotubes
| Project/Area Number |
13440127
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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 |
物理学一般
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| Research Institution | Waseda University |
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Principal Investigator |
TAKEDA Kyozaburo Waseda University, School of Science and Engineering, Professor, 理工学部, 教授 (40277851)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRAISHI Kenji University of Tsukuba, Physics, associate professor, 物理学系, 助教授 (20334039)
MIHARA Hisakazu Tokyo Institute of Technology, Bioscience & Biotechnology, associate professor, 生命理工学部, 助教授 (30183966)
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| Project Period (FY) |
2001 – 2003
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| Keywords | Protein nanotube / Protein nanoring / Mathematical molecular desigining / Ab initio molecular orbitals theory / D.L alternating amino acids rings / Synthesis and AFM observation / Electronic structure / Molecular structure |
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| Research Abstract |
The peptide nanotube (PNT) is formed by the spontaneous stacking of cyclic peptides (or peptide nanorings ; PNRs) consisting of an alternate sequence of D-and L-amino acid residues (D,L-peptide). Because of its peculiar periodic structure with an open-ended hollow core, PNT has attracted the interest of many scientists. An aim of the present project is to provide the guiding principle of molecular modeling in PNRs and peptide PNTs. For this purpose, possible molecular conformations of PNRs and PNTs were mathematically investigated and novel types of backbone structures were explored by the numerical conformation analysis. The energetically stable backbone forms of the PNRs and PNTs were also studied, and the electronic structures were discussed based on ab initio molecular orbital calculations. The effects of the amino acid substitution were studied and the electronic characteristics of the individual side chains were systematically understood. Not only the theoretical studies, but also the synthesis and atomic force microscopy were carried out for the D,L-peptide nanotubes. PNTs having six, and eight amino acid residues were synthesized and their self-assembling morphologies were compared in terms of the difference in the number of component amino acid residues. In addition to the D,L-peptide nanotubes, an unusual peptide nanotube consisting of all the L-amino acid residues was newly synthesized. Following the theoretical prediction and synthesis, an atomic force microscopy study of the homo-L-pentapeptide nanotube was carried out and the self-assembling morphology was discussed.
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