Construction of a Synchrotron-Radiation Vacuum-Ultraviolet Circular-Dichroism Spectrophotometer and Its Application to the Structural Analysis of Biomolecules

Abstract

A vacuum-ultraviolet (VUV) circular-dichroism (CD) spectrophotometer usable down to 140 nm was constructed using synchrotron radiation and applied to the structural analyses of various saccharides, amino acids, and proteins in aqueous solutions. Most monosaccharides and disaccharides exhibited a positive CD peak around 170 nm, depending on anomeric and axial/equatorial configurations of hydroxy groups, transgauche configurations of hydroxymethyl groups, and the type of glycosidic linkage. The VUVCD spectra of glycosaminoglycans sensitively reflected the characteristic contributions of constituent functional groups in the VUV region. L-Isomers of amino acids showed two successive positive peaks around 200 and 180 nm, depending on the types of side chains. The VUVCD spectrum of alanine theoretically calculated using a time-dependent density functional theory revealed the important role of hydration for stabilizing the alanine structure. The VUVCD spectra of native proteins down to 160 nm improved the predictive accuracy for the contents, numbers of segments, and sequences of ¡-helices and ¢-strands. These secondary-structure analyses were also successfully applied to various types of nonnative proteins. The obtained results demonstrate that synchrotronradiation VUVCD spectroscopy is a powerful technique for the structural analysis of biomolecules in aqueous solution, and hence could open a new field in structural biology.

Vacuum-ultraviolet circular dichroism study of oligosaccharides using a synchrotron-radiation spectrophotometer

“…However, the relationships between the conformations and VUVCD of oligosaccharides remain controversial due to the interpretation of the observed CD spectra in the VUV region not being entirely consistent or being assigned explicitly. Therefore, more comprehensive VUVCD spectra data obtained using an SR light source -which can provide a higher flux of photons in the VUV region compared to other experimental light sources [18,41] -are indispensable for understanding how the oligosaccharide structures in aqueous solution contribute to the measured CD spectra.…”

Structural Alterations of Histone Proteins in DNA-Damaged Cells Revealed by Synchrotron Radiation Circular Dichroism Spectroscopy: A New Piece of the DNA-Damage-Response Puzzle

“…The spectra discussed hereafter were obtained using the V-630 Bio spectrophotometer (JASCO, Tokyo, Japan). CD spectroscopy of H2A-H2B and H3-H4 was carried out at the DISCO beamline of Synchrotron SOLEIL [47] and BL-12 of HiSOR [42], respectively. The CD spectra that were obtained at 25 °C are discussed hereafter.…”

“…At the time of writing, to my knowledge, synchrotron radiation circular dichroism (SRCD) spectroscopy can be performed at eight SR facilities: Hiroshima Synchrotron Radiation Center (HiSOR) in Japan [42], Institute for Storage Ring Facilities (ISA) in Denmark [43], Beijing Synchrotron Radiation Facility (BSRF) in China [44], National Synchrotron Radiation Research Center (NSRRC) in Taiwan [45], Diamond Light Source (DLS) in UK [46], Synchrotron SOLEIL in France [47], BESSY-II [48], and ANKA [49] in Germany. In general, SRCD experiments can be performed after the acceptance of proposal(s), which can be referred to the websites of each SR facility.…”

“…Demountable cells are often used for SRCD spectroscopy due to their ease of cleaning because short path length is preferable. Since SRCD measurements are sometimes carried out in the wavelength region down to 160 nm [39,42], sample cells are often made of calcium fluoride (CaF 2 ) around which transmittance is higher than quartz (SiO 2 ) used for conventional CD spectroscopy (the cutoff wavelength is~140 nm for CaF 2 and~160 nm for SiO 2 ).…”

“…The CD measurement systems used in SR facilities are similar to those of commercial CD spectrophotometers, although important details should be checked in publications [42][43][44][45][46][47][48][49] and on the websites of each facility. In general, SR is monochromated and converted LCPL or RCPL using a phase shifter (photo-elastic modulator).…”