Stopped-Flow Ultra-Rapid-Scanning Fourier Transform Infrared Spectroscopy on the Millisecond Time Scale

Reback, Matthew L.; Roske, Christopher W.; Bitterwolf, Thomas E.; Griffiths, Peter R.; Manning, Christopher J.

doi:10.1366/000370210792081019

Cited by 4 publications

(2 citation statements)

References 20 publications

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“…In practice, because the moving mirror needs to be accelerated and deaccelerated rapidly, it is impossible to realize a time resolution better than a few microseconds unless there is a radical change in design of the interferometers, explaining why the time-resolution of rapid-scan in commercial FT-IR spectrometers has not improved for the last 30 years. To overcome these limitations, an alternative interferometer design using a rotating wedge mirror was presented 20 years ago, reporting on the acquisition of interferograms at 1 ms temporal and 4 cm −1 spatial resolution, 452 but published implementations have only achieved a time resolution of 5 ms for 6 cm −1 spectral resolution 453 Also, its applicability to obtain time-resolved IR difference spectra of proteins has not been demonstrated to my knowledge.…”

Section: Time-resolved Methodsmentioning

confidence: 99%

Infrared Difference Spectroscopy of Proteins: From Bands to Bonds

2020

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Infrared difference spectroscopy probes vibrational changes of proteins upon their perturbation. Compared with other spectroscopic methods, it stands out by its sensitivity to the protonation state, H-bonding, and the conformation of different groups in proteins, including the peptide backbone, amino acid side chains, internal water molecules, or cofactors. In particular, the detection of protonation and H-bonding changes in a timeresolved manner, not easily obtained by other techniques, is one of the most successful applications of IR difference spectroscopy. The present review deals with the use of perturbations designed to specifically change the protein between two (or more) functionally relevant states, a strategy often referred to as reaction-induced IR difference spectroscopy. In the first half of this contribution, I review the technique of reaction-induced IR difference spectroscopy of proteins, with special emphasis given to the preparation of suitable samples and their characterization, strategies for the perturbation of proteins, and methodologies for time-resolved measurements (from nanoseconds to minutes). The second half of this contribution focuses on the spectral interpretation. It starts by reviewing how changes in H-bonding, medium polarity, and vibrational coupling affect vibrational frequencies, intensities, and bandwidths. It is followed by band assignments, a crucial aspect mostly performed with the help of isotopic labeling and site-directed mutagenesis, and complemented by integration and interpretation of the results in the context of the studied protein, an aspect increasingly supported by spectral calculations. Selected examples from the literature, predominately but not exclusively from retinal proteins, are used to illustrate the topics covered in this review.

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Section: Time-resolved Methodsmentioning

confidence: 99%

Infrared Difference Spectroscopy of Proteins: From Bands to Bonds

2020

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“…Recently, CD detection is commonly employed to study protein folding kinetics [68], while ultraviolet CD was used to study the folding mechanism of the outer surface protein A. Kinetic measurements in a stopped-flow mode are also used with Fourier-transform infrared (FTIR) detection [69], whereas NMR spectroscopy was reported, for instance, in the examination of metallocene-catalyzed poly-merization of 1-hexene [70].…”

Section: Fundamental Physico-chemical Measurements Under Flow Conditionsmentioning

confidence: 99%

Flow Chemistry in Contemporary Chemical Sciences: A Real Variety of Its Applications

Trojanowicz

2020

Molecules

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Flow chemistry is an area of contemporary chemistry exploiting the hydrodynamic conditions of flowing liquids to provide particular environments for chemical reactions. These particular conditions of enhanced and strictly regulated transport of reagents, improved interface contacts, intensification of heat transfer, and safe operation with hazardous chemicals can be utilized in chemical synthesis, both for mechanization and automation of analytical procedures, and for the investigation of the kinetics of ultrafast reactions. Such methods are developed for more than half a century. In the field of chemical synthesis, they are used mostly in pharmaceutical chemistry for efficient syntheses of small amounts of active substances. In analytical chemistry, flow measuring systems are designed for environmental applications and industrial monitoring, as well as medical and pharmaceutical analysis, providing essential enhancement of the yield of analyses and precision of analytical determinations. The main concept of this review is to show the overlapping of development trends in the design of instrumentation and various ways of the utilization of specificity of chemical operations under flow conditions, especially for synthetic and analytical purposes, with a simultaneous presentation of the still rather limited correspondence between these two main areas of flow chemistry.

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Time-resolved mid-IR spectroscopy of (bio)chemical reactions in solution utilizing a new generation of continuous-flow micro-mixers

et al. 2011

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A specially designed micro-mixer made of silicon, calcium fluoride, and silicone with an optical transmission path of 8 μm has been used for mid-IR spectroscopy monitoring of mixing-induced chemical reactions in the low millisecond time regime. The basic principle of the proposed continuous-flow technique is to mix two liquids introduced in two times two alternatingly stacked layers through diffusion at the entrance of a 200 μm wide, 1 cm long micro-fluidic channel also serving as measurement area. By using this special, dedicated arrangement, diffusion lengths and hence the mixing times can be significantly shortened and the overall performance improved in comparison to previous systems and alternative methods. Measurements were carried out in transmission mode using an Fourier transform infrared (FTIR) microscope, recording spectra with spot sizes of 180 × 100 μm(2) each at defined spots along this channel. Each of these spots corresponds to a specific reaction time: moving the measurement spot towards the entry yields shorter reaction times, moving it towards the channel's end gives longer reaction times. This principle is generic in nature and provides a solution for accurate, chemically induced triggering of reactions requiring the mixing of two liquid reagents or reagent solutions. A typical experiment thus yields up to 85 time-coded data points, covering a time span from 1 to 80 ms at a total reagent consumption of only about 125 μL. Using the fast neutralization reaction of acetic acid with sodium hydroxide as a model, the time required for 90% mixing was determined to be around 4 ms. Additionally, first experiments on ubiquitin changing its secondary structure from native to "A-state" were carried out, illustrating the potential for time-resolved measurements of proteins in aqueous solutions.

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Stopped-Flow Ultra-Rapid-Scanning Fourier Transform Infrared Spectroscopy on the Millisecond Time Scale

Cited by 4 publications

References 20 publications

Infrared Difference Spectroscopy of Proteins: From Bands to Bonds

Infrared Difference Spectroscopy of Proteins: From Bands to Bonds

Flow Chemistry in Contemporary Chemical Sciences: A Real Variety of Its Applications

Time-resolved mid-IR spectroscopy of (bio)chemical reactions in solution utilizing a new generation of continuous-flow micro-mixers

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