Synchrotron Radiation Circular Dichroism Beamline Research Articles

Diamond B23 CD Imaging of Thin Films of Chiral Materials or Achiral Polymers Coated with Chiral Molecules

The novel vertical sample chamber, developed at the B23 beamline for synchrotron radiation circular dichroism (SRCD), has enabled the Diamond User community to conduct different types of experiments from high throughput CD of protein and DNA folding using 96-well multiplates to CD imaging at high spatial resolution. Here, we present the application of CD imaging to large areas of achiral polymer PVA films doped with D-dopa to assess the chiral homogeneity of the film preparation with potential antimicrobial property. Synopsis: CDi application of Diamond B23 SRCD beamline.

UV-CD12: synchrotron radiation circular dichroism beamline at ANKA.

Synchrotron radiation circular dichroism (SRCD) is a rapidly growing technique for structure analysis of proteins and other chiral biomaterials. UV-CD12 is a high-flux SRCD beamline installed at the ANKA synchrotron, to which it had been transferred after the closure of the SRS Daresbury. The beamline covers an extended vacuum-UV to near-UV spectral range and has been open for users since October 2011. The current end-station allows for temperature-controlled steady-state SRCD spectroscopy, including routine automated thermal scans of microlitre volumes of water-soluble proteins down to 170 nm. It offers an excellent signal-to-noise ratio over the whole accessible spectral range. The technique of oriented circular dichroism (OCD) was recently implemented for determining the membrane alignment of α-helical peptides and proteins in macroscopically oriented lipid bilayers as mimics of cellular membranes. It offers improved spectral quality <200 nm compared with an OCD setup adapted to a bench-top instrument, and accelerated data collection by a factor of ∼3. In addition, it permits investigations of low hydrated protein films down to 130 nm using a rotatable sample cell that avoids linear dichroism artifacts.

Circular dichroism beamline B23 at the Diamond Light Source

Synchrotron radiation circular dichroism (SRCD) is a well established technique in structural biology. The first UV-VIS beamline, dedicated to circular dichroism, at Diamond Light Source Ltd, a third-generation synchrotron facility in south Oxfordshire, UK, has recently become operational and it is now available for the user community. Herein the main characteristics of the B23 SRCD beamline, the ancillary facilities available for users, and some of the recent advances achieved are summarized.

Synchrotron radiation circular dichroism (SRCD) spectroscopy: An emerging method in structural biology for examining protein conformations and protein interactions

Circular dichroism (CD) spectroscopy is a well-established technique in structural biology. The use of synchrotron radiation as an intense light source for these measurements extends the applications possible using lab-based instruments. In recent years, there has been a major growth in synchrotron radiation circular dichroism (SRCD) beamlines worldwide, including ones at the NSLS, ISA, SRS, HiSOR, BSRF, NSRRC, SOLEIL, Diamond, TERAS, BESSYII, and ANKA synchrotrons. Through the coordinated efforts of beamline scientists and users at these sites, important proof-of-principle studies have been done enabling the method to be developed for novel and productive studies on biological systems. This paper describes the characteristics of SRCD beamlines and some of the new types of applications that have been undertaken using these beamlines.

Measuring circular dichroism in a capillary cell using the b23 synchrotron radiation CD beamline at diamond light source

Synchrotron radiation circular dichroism (SRCD) is a well-established method in structural biology. The first UV-VIS beamline dedicated to circular dichroism at Diamond Light Source, a third generation synchrotron facility in South Oxfordshire, has recently become operational and it is now available for the user community. Herein we present an important application of SRCD: the CD measurement of protein solutions in fused silica rectangular capillary cells. This was achieved without the use of any lens between the photoelastic modulator and the photomultiplier tube detectors by exploiting the high photon flux of the collimated beam that can be as little as half a millimeter squared. Measures to minimize or eliminate vacuum-UV protein denaturation effects are discussed. The CD spectra measured in capillaries is a proof of principle to address CD measurements in microdevice systems using the new B23 SRCD beamline.

Light flux density threshold at which protein denaturation is induced by synchrotron radiation circular dichroism beamlines

New high-flux synchrotron radiation circular dichroism (SRCD) beamlines are providing important information for structural biology, but can potentially cause denaturation of the protein samples under investigation. This effect has been studied at the new CD1 dedicated SRCD beamline at ISA in Denmark, where radiation-induced thermal damage effects were observed, depending not only on the radiation flux but also on the focal spot size of the light. Comparisons with similar studies at other SRCD facilities worldwide has lead to the estimation of a flux density threshold under which SRCD beamlines should be operated when samples are to be exposed to low-wavelength vacuum ultraviolet radiation for extended periods of time.

Synchrotron Radiation Circular Dichroism (SRCD) spectroscopy: New beamlines and new applications in biology

New advances in instrumentation, demonstration of proof-of-principle studies, and development of new tools and methods for data analysis and interpretation have enabled the technique of Synchrotron Radiation Circular Dichroism (SRCD) spectroscopy to become a useful tool for structural and functional biology. This paper discusses the characterisation of two new SRCD beamlines, CD1 at the Institute for Storage Rings (ISA), Denmark and 4B8 at the Beijing Synchrotron Radiation Facility (BSRF), China, and new applications of the method for examining biological systems.

Meeting Reports: International Workshop on the Protein Circular Dichroism Data Bank

The International Workshop on the Protein Circular Dichroism Data Bank (PCDDB) was held on April 11–13, 2005, at Birkbeck College, University of London, UK, under the sponsorship of the UK Biotechnology and Biological Sciences Research Council. The meeting was chaired by Bonnie Ann Wallace, Professor in the Department of Crystallography at Birkbeck College. The workshop organizing committee consisted of Dr. Robert W. Janes, Queen Mary, University of London, and Dr. Lee Whitmore, also of Birkbeck College. Participants included experts in both conventional circular dichroism (CD) spectroscopy and representatives from synchrotron radiation circular dichroism (SRCD) beamlines: Prof. J. Sutherland of the NSLS SRCD beamlines U9b and U11 and East Carolina University (USA);

Overcoming protein denaturation caused by irradiation in a high-flux synchrotron radiation circular dichroism beamline

It has been established that the new circular dichroism beamline CD12 has sufficiently high flux at low wavelengths to cause apparent irradiation problems with protein samples while their synchrotron radiation circular dichroism (SRCD) spectra are being collected. The cause of this effect has been extensively investigated and is reported in an accompanying paper [Wien et al. (2005). J. Synchrotron Rad. 12, 517-523.]. Experiments suggest that localized heating of the protein sample, leading to denaturation, is the probable cause. Methods to circumvent this problem by limiting the beam flux are reported. This was achieved using either an attenuation cell of water placed beam-side of the sample cell, or limiting the beam cross-sectional area hitting the sample. Such methods are shown to result in substantial reduction or apparent complete removal of this protein denaturation over the course of collecting three successive spectra. Elimination of this denaturation problem enables multiple SRCD scans for protein samples to be collected, which are vital both for good practice and for statistically valid results.