X-ray absorption spectrum for guanosine-5'-monophosphate in water solution in the vicinity of the nitrogen K-edge observed in free liquid jet in vacuum

Ukai, Masatoshi*; Yokoya, Akinari; Fujii, Kentaro; Saito, Yuji  

In order to substantiate the hydrated structure of DNA from the view point of the electronic properties, we develop a new spectroscopic technique for the photoelectrons ejected from solutions dissolving biological molecules using a soft X-ray synchrotron radiation (SPring-8, BL23SU) in combination with liquid jet technique in vacuum. In this paper, we present the first evidence of the spectrum of total photoelectron yields for a nucleotide, guanosine-5'-monophosphate, in solution in the energy region of so-called water window around nitrogen K-edge. A liquid nucleotide/water sample is maintained in the form of continuous thin water jet (diameter 20 m) in vacuum and is intersected by a highly focused soft X-ray beam. The obtained spectrum in solution shows common features with the spectrum in solid film. Nitrogen atoms only exist in the base site, so that the spectral similarities can be explained by the hydrophobic property of the base site.