| Project/Area Number |
10680571
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Bioorganic chemistry
|
|---|
| Research Institution | Graduate School of Science & Technology, Kumamoto University |
|---|
Principal Investigator |
IHARA Hirotaka Kumamoto University, Graduate School of Science & Technology, Professor, 大学院・自然科学研究科, 教授 (10151648)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
SAGAWA Takashi Kumamoto University, Department of Applied Chemistry & Biochemistry, Assistant Professor, 工学部, 助手 (20225832)
|
|---|
| Project Period (FY) |
1998 – 1999
|
| Project Status |
Completed (Fiscal Year 1999)
|
| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥2,500,000 (Direct Cost: ¥2,500,000)
|
|---|
| Keywords | bilayer / gel / amphiphilic property / molecular aggregation / amino acid / optical activity / 両親媒性 |
|---|
| Research Abstract |
L-glutamic acid-derived lipids were synthesized in order to study the aggregation structures in organic solvents and discussed the driving force for aggregation.
a) Triamide-containing lipids derived from L-glutamic acid produced organic gels through formation of lipid aggregation by hydrogen bonding interaction among the amide moieties. This gelation was formed in various organic solution such as methanol, ethanol, benzene, tetrahydrofuran, toluene and cyclohexane.
b) TEM observation showed that the xerogel after freeze-dried from the clear gel was constructed from a network of microfibrous aggregates. But no similar network was observed at the low concentration (in the sol state) while fragmental microfibers were detectable. It was confirmed that critical gelation (cgc) depended on the kind of organic solvents. For example, the cgc lies between 1 and 0.1 mM at room temperature in benzene. However, SEM and TEM observations showed that fibrous aggregates were produced at lower concentrat
… More
ion such as 0.01 mM than cgc. This shows that the cgc doesn't agree with the critical aggregation concentration (cac). Therefore, the gel formation is attributed to the development of fibrous aggregates and subsequent formation of an aggregate network.
c) To estimate cac and the aggregation structure, we synthesized new lipids having pyrenyl head group. By fluorescence emission spectra showed that the lipids produced excimers at the concentration above cac.
d) We synthesized triamide-containing L-glutamic acid lipid with tetraalkyl groups and a protoporphyrin IX-head group. The lipid produced highly-oriented fibrous aggregates in organic solution such as benzene, cyclohexane and so on. UV-vis spectra indicated formation of a Soret band which was estimated by red shift phenomena, but these were lost by addition of trifuluoroacetic acid (TFA ) to provide spectra corresponding to those in monomeric dispersion states. CD spectra showed that the aggregates induced positive Cotton effect but addition of TFA reduced the elipticity. These results indicate that hydrogen bonding work as a driving force for aggregation and the cofacial packed-porphyrin planar structure will be included. Less
|
