New technique for measuring circular dichroism changes on a nanosecond time scale. Application to (carbonmonoxy)myoglobin and (carbonmonoxy)hemoglobin

Lewis, James W.; Tilton, Robert D.; Einterz, C. M.; Milder, Steven J.; Kuntz, Irwin D.; Kliger, David S.

doi:10.1021/j100248a023

Cited by 94 publications

(69 citation statements)

References 3 publications

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“…Cytochrome c folds in a multi-step reaction, involving multiple paths, starting on the μs timescale and completed on the second timescale. To follow early events in folding on the ns to ms timescale we used a ns time-resolved CD (TRCD) approach developed in the Kliger lab (Lewis et al 1985;Kliger et al 2012). In this study, electron-transfer (ET)-triggered folding was probed by TRCD and the results demonstrated that there were changes in kinetic partitioning between fast and slow folding phases of cytochrome c in the presence of 220 mg/ml dextran 70.…”

Section: Macromolecular Crowding Effects On Folding Dynamicsmentioning

confidence: 99%

Effects of macromolecular crowding agents on protein folding in vitro and in silico

et al. 2013

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Proteins fold and function inside cells which are environments very different from that of dilute buffer solutions most often used in traditional experiments. The crowded milieu results in excluded-volume effects, increased bulk viscosity and amplified chances for intermolecular interactions. These environmental factors have not been accounted for in most mechanistic studies of protein folding executed during the last decades. The question thus arises as to how these effects-present when polypeptides normally fold in vivo-modulate protein biophysics. To address excluded volume effects, we use synthetic macromolecular crowding agents, which take up significant volume but do not interact with proteins, in combination with strategically selected proteins and a range of equilibrium and time-resolved biophysical (spectroscopic and computational) methods. In this review, we describe key observations on macromolecular crowding effects on protein stability, folding and structure drawn from combined in vitro and in silico studies. As expected based on Minton's early predictions, many proteins (apoflavodoxin, VlsE, cytochrome c, and S16) became more thermodynamically stable (magnitude depends inversely on protein stability in buffer) and, unexpectedly, for apoflavodoxin and VlsE, the folded states changed both secondary structure content and, for VlsE, overall shape in the presence of macromolecular crowding. For apoflavodoxin and cytochrome c, which have complex kinetic folding mechanisms, excluded volume effects made the folding energy landscapes smoother (i.e., less misfolding and/or kinetic heterogeneity) than in buffer.

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Section: Macromolecular Crowding Effects On Folding Dynamicsmentioning

confidence: 99%

Effects of macromolecular crowding agents on protein folding in vitro and in silico

et al. 2013

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“…In this way the chiral contribution becomes a larger fraction of the detected signal and it is no longer measured as a tiny difference between two very large intensities. Crossed polarizer schemes are already used in nanosecond electronic CD [7] and ORD [54] spectroscopy by Kliger and coworkers, and an interesting variant was recently introduced by Niezborala and Hache. [55] In their setup a linearly polarized probe beam passes the sample, followed by a waveplate with small, variable birefringence (Babinet-Soleil compensator) and a crossed polarizer before being detected.…”

Section: Technical Developmentsmentioning

confidence: 99%

“…Complementary to dichroism measurements (probing the difference in absorption of left-and righthanded circular polarized light) changes in optical rotation could also be detected. [6] The use of pulsed lasers for photo triggering has made it possible to resolve transient changes in circular dichroism first with nanosecond [7] and later picosecond [8] time-resolution (see ref. [9] for a review of the initial development of the field).…”

Section: Introductionmentioning

confidence: 99%

Time-Resolved Chiral Vibrational Spectroscopy

Helbing¹,

Bonmarin²

2009

Chimia

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Advances in infrared laser technology and detection sensitivity have made time-resolved chiral vibrational spectroscopy experimentally feasible. Here we describe our recent efforts in detecting, for the first time, transient vibrational circular dichroism (VCD) signals with picosecond time resolution. The absorption changes of the cobalt (−)-sparteine complex Co(sp)Cl2 after visible excitation of a d-d excited state was probed in the CH-stretch region by alternating left-and right-handed circular polarized mid IR laser pulses. VCD spectra can be sensitive reporters of peptide and protein secondary structure or the absolute configuration of chiral organic compounds in solution. Recent developments are presented, which may in the future allow us to access this information in the course of fast chemical reactions.128 CHIMIA 2009, 63, No. 3 Young AcAdemics in switzerlAnd PArt ii doi:10.2533doi:10. /chimia.2009doi:10. .128 Chimia 63 (2009

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“…Although this approach has the advantage of elimination of analyzing the polarization of the sample passing through light, quantitative discussion might be difficult, since the control of polarization states of probe light is insufficient. As these works suggested, there should be a frontier for exploring for the timeresolved CD (TR-CD) experiment even in 2010.In pioneer work in the 1980s, Kliger et al 4 clearly demonstrated that pseudo-linearly elliptically polarized light, generated by a low power compressed quartz plate retarder, was able to enhance CD signal intensities and then be applied to TR-CD detection with high S/N. Although their approach was a great accomplishment, a fundamental difficulty arose from the specialized retarder.…”

mentioning

confidence: 99%

“…In pioneer work in the 1980s, Kliger et al 4 clearly demonstrated that pseudo-linearly elliptically polarized light, generated by a low power compressed quartz plate retarder, was able to enhance CD signal intensities and then be applied to TR-CD detection with high S/N. Although their approach was a great accomplishment, a fundamental difficulty arose from the specialized retarder.…”

mentioning

confidence: 99%

Remarkable Enhancement of Sensitivity with the Second Generation of Elliptically Polarization-detected Circular Dichroism Spectroscopy

Murakami¹,

Araki²,

Sakamoto³

et al. 2013

Chemistry Letters

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A new circular dichroism (CD) measurement system based on the detection of elliptically polarized light has been proposed. The approach has several unique and inherent advantages, such as sensitivities, reliability, and reproducibility, over conventional systems and Kliger's pioneering work. We have rederived the Jones calculus and introduced the angular term into the formulation revealing that this approach should improve the signal intensity by controlling the light ellipticity. Therefore, we have first demonstrated the hypothesis by the quantitative analysis of the signal intensity measuring of the split CD pattern of tris(bipyridine)-ruthenium(II) dichloride with the system. The CD signals increasing with decreasing the azimuth of retarder was clearly observed, enabling detection of CD signal with high sensitivity.Circular dichroism (CD) spectrometry is one of the most powerful and versatile methods for detection of interaction and binding of biomolecules, since these molecules consist of chiral unit modules.1 Thus, these conformational and structural changes and/or variety could be observed by CD spectra with high sensitivities. However, it is hard to measure CD spectra with good to excellent S/N, in general, as a result of small differences in extinction coefficients of asymmetric left and right circularly polarized light (¦¾). It is well known that the ¦¾ values are mostly three orders of magnitude lower than those of the UVvis (¾). Therefore, CD spectral studies have been predominantly confined to relatively high-concentration samples. In order to improve the sensitivity, a lock-in detection system with a photoelastic modulator (PEM) has been successfully employed in modern CD instruments. However, the modulation frequencies of asymmetric circular polarized lights of PEM (ca. 45 KHz) limit time-resolution of CD measurements. Therefore, CD spectral studies have been mostly focused on relatively slow events. Hence, novel CD detection methods for appropriate time resolution for observing early events such as protein folding are desired.These unique properties and advantages of CD measurements have driven our research interest and endeavor to creation of a novel methodology for detection and observation of CD spectra coping with both high sensitivity and high time resolution broadly in science and technology. To achieve this purpose, small differences in ¦¾ between large quantities of ¾ must be detected. For this purpose, several approaches for CD detection without PEM-based lock-in detection systems have been proposed recently. Hache et al. have reported that singular utilization for the polarization of light with a Babinet compensator could be applied for CD dynamics studies on 1,1¤-bi-2-naphthol. 2 Another approach had been proposed by Fiebig et al. 3 Their approach aimed to obtain CD signals more directly. The sophisticated way for transient absorption measurement with polarization-controlled white light could measure the differential absorption of circular polarized light generated by chiral sample...

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New technique for measuring circular dichroism changes on a nanosecond time scale. Application to (carbonmonoxy)myoglobin and (carbonmonoxy)hemoglobin

Cited by 94 publications

References 3 publications

Effects of macromolecular crowding agents on protein folding in vitro and in silico

Effects of macromolecular crowding agents on protein folding in vitro and in silico

Time-Resolved Chiral Vibrational Spectroscopy

Remarkable Enhancement of Sensitivity with the Second Generation of Elliptically Polarization-detected Circular Dichroism Spectroscopy

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