|Budget Amount *help
¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 2002 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 2001 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 2000 : ¥2,100,000 (Direct Cost : ¥2,100,000)
Raman optical activity (ROA) is observed as the difference Raman spectra between right and lefthanded circularly polarized incident lights. This effect is expected to be dominant for collectivevibrations of helical structure, which appear in the low-frequency region. We aimed to observelow-frequency ROA of biological molecules, such as nucleic acids, and proteins.
The system is specially designed for low-frequency region measurements, consisting of amechanically rotating 1/4 λ, wave plate with linear polarizer, and a double monochrofnator with wave scan, and photon counting electronics.To avoid sample damage, the laser power is lowered, nevertheless , the long time exposure resulted degradation. We need transparent, and big sample not to disturb the polarization, which makes it difficult to prepare samples.
We measured a helix rich protein solutions, such as poly-L-lysine in PHIO, insulin, apoferritin,and bacterio rhodopsin. We could find no trace ofnon-trivial signals. The ROA spectra of lysozyme crystals showed, hopefully, tiny signals. We will proceed to increase the S/N ratio.The neat liquids that maintain helical structure just above the melting points seem to be a future target for low-frequency ROA.