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2D-O1-0910 PDF
液滴分子線赤外レーザー蒸発法により気相単離したタンパク質分子のレーザー分光
The molecular function of the water molecules surrounding protein molecules can be scrutinized by observing their properties as a function of the hydration number. In such studies, it is necessary to isolate the hydrated protein molecules in the gas phase. We have then developed a novel isolation technique, droplet-beam IR-laser ablation method. We have employed a UV laser induced proton-transfer reaction of the gas-phase protein as a probe for the investigations on the protein structures by gas-phase laser spectroscopies.
A droplet beam was introduced in front of an inlet aperture of a differentially-pumped vacuum chamber. The droplet was transported into an acceleration region of a time-of-flight spectrometer and was irradiated with an IR laser. Produced ions were irradiated by a subsequent UV laser for photodissociation. The ions were then mass-analyzed. For a photodissociation spectroscopy, particular ion was trapped in an ion trap and the excitation spectrum of the UV photodissociation product ion was measured by scanning the UV-laser wavelength.
The photodissociation spectrum of Lys2+ peaks at <195, 210, and 230 nm with narrower bandwidth than the solution spectrum, which results from decrease of inhomogeneity by hydration in the solution by isolation in the gas phase. This technique is therefore revealed to be applicable to investigation on the hydration effect to protein molecules.