scholarly journals Two-Step Structural Changes in Orange Carotenoid Protein Photoactivation Revealed by Time-Resolved Fourier Transform Infrared Spectroscopy

2019 ◽  
Vol 123 (15) ◽  
pp. 3259-3266 ◽  
Author(s):  
Alberto Mezzetti ◽  
Maxime Alexandre ◽  
Adrien Thurotte ◽  
Adjelé Wilson ◽  
Michal Gwizdala ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Structural Changes ◽  
Fourier Transform Infrared ◽  
Time Resolved ◽  
Orange Carotenoid Protein

Real-Time Pursuit of Crystal Growth by Millisecond Time-Resolved Multichannel Fourier Transform Infrared Spectroscopy

1998 ◽  
Vol 52 (2) ◽  
pp. 222-225
Author(s):  
Mamoru Hashimoto ◽  
Hiro-O Hamaguchi
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Structural Change ◽  
Liquid Phase ◽  
Fourier Transform Infrared Spectroscopy ◽  
Molecular Orientation ◽  
Structural Changes ◽  
Fourier Transform Infrared ◽  
Time Resolved ◽  
Recovery Curves

The surface (about 130 molecular layers) of an oriented thin crystal of decanoic acid was subjected to sudden melting by a laser-induced temperature jump (T-jump), and the process of subsequent crystal re-growth was monitored by millisecond time-resolved multichannel Fourier transform infrared spectroscopy. The gauche–trans structural change of the alkane part of the molecule has been probed by the CH stretch bands in the 2800–3000 cm−1 region. The change in the molecular orientation has been detected by the OH stretch band around 3065 cm−1. The recovery curves for the CH2 antisymmetric stretch and the OH stretch bands are markedly different from each other in the first 200 ms, suggesting that the gauche–trans structural changes precedes the crystal re-growth. After 500 ms, the recovery curves become identical. This result means that the rate of the gauche to the trans structural change is equal to the rate of the recovery of the molecular orientation. It is highly likely that a fast equilibrium is attained between the gauche and the trans conformations in the liquid phase after 500 ms from the sudden melting and that the crystal re-growth takes place solely via the all-trans structure in the liquid phase.

scholarly journals Fourier Transform Infrared Spectroscopy on the Rap·RapGAP Reaction, GTPase Activation without an Arginine Finger

2004 ◽  
Vol 279 (44) ◽  
pp. 46226-46233 ◽  
Author(s):  
Partha P. Chakrabarti ◽  
Yan Suveyzdis ◽  
Alfred Wittinghofer ◽  
Klaus Gerwert
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Structural Changes ◽  
Fourier Transform Infrared ◽  
Cleavage Reaction ◽  
Gtp Hydrolysis ◽  
Time Resolved ◽  
Gtpase Activation ◽  
Arginine Finger

GTPaseactivatingproteins (GAPs) down-regulate Ras-like proteins by stimulating their GTP hydrolysis, and a malfunction of this reaction leads to disease formation. In most cases, the molecular mechanism of activation involves stabilization of a catalytic Gln and insertion of a catalytic Arg into the active site by GAP. Rap1 neither possesses a Gln nor does its cognate Rap-GAP employ an Arg. Recently it was proposed that RapGAP provides a catalytic Asn, which substitutes for the Gln found in all other Ras-like proteins (Daumke, O., Weyand, M., Chakrabarti, P. P., Vetter, I. R., and Wittinghofer, A. (2004)Nature429, 197–201). Here, RapGAP-mediated activation has been investigated by time-resolved Fourier transform infrared spectroscopy. Although the intrinsic hydrolysis reactions of Rap and Ras are very similar, the GAP-catalyzed reaction shows unique features. RapGAP binding induces a GTP*conformation in which the three phosphate groups are oriented such that they are vibrationally coupled to each other, in contrast to what was seen in the intrinsic and the Ras·RasGAP reactions. However, the charge shift toward β-phosphate observed with RasGAP was also observed for RapGAP. A GDP·Piintermediate accumulates in the GAP-catalyzed reaction, because the release of Piis eight times slower than the cleavage reaction, and significant GTP synthesis from GDP·Piwas observed. Partial steps of the cleavage reaction are correlated with structural changes of protein side groups and backbone. Thus, the Rap·RapGAP catalytic machinery compensates for the absence of acis-Gln by atrans-Asn and for the catalytic Arg by inducing a different GTP conformation that is more prone to be attacked by a water molecule.

Dependence of the intrinsic phase structure of Bi2O3 catalysts on photocatalytic CO2 reduction

2021 ◽  
Vol 11 (6) ◽  
pp. 2021-2025
Author(s):  
Liujin Wei ◽  
Guan Huang ◽  
Yajun Zhang
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Phase Structure ◽  
Co2 Reduction ◽  
Fourier Transform Infrared ◽  
Time Resolved ◽  
Dependent Activity

The combination of time-resolved transient photoluminescence with in-situ Fourier transform infrared spectroscopy has been conducted to investigate the intrinsic phase structure-dependent activity of Bi2O3 catalyst for CO2 reduction.

scholarly journals Probing the Proton-Loading Site of Cytochrome C Oxidase Using Time-Resolved Fourier Transform Infrared Spectroscopy

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3393
Author(s):  
Elena Gorbikova ◽  
Sergey A. Samsonov ◽  
Ruslan Kalendar
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Fourier Transform Infrared Spectroscopy ◽  
Paracoccus Denitrificans ◽  
Fourier Transform Infrared ◽  
Double Difference ◽  
Time Resolved ◽  
Fast Kinetic

Crystal structure analyses at atomic resolution and FTIR spectroscopic studies of cytochrome c oxidase have yet not revealed protonation or deprotonation of key sites of proton transfer in a time-resolved mode. Here, a sensitive technique to detect protolytic transitions is employed. In this work, probing a proton-loading site of cytochrome c oxidase from Paracoccus denitrificans with time-resolved Fourier transform infrared spectroscopy is presented for the first time. For this purpose, variants with single-site mutations of N131V, D124N, and E278Q, the key residues in the D-channel, were studied. The reaction of mutated CcO enzymes with oxygen was monitored and analyzed. Seven infrared bands in the “fast” kinetic spectra were found based on the following three requirements: (1) they are present in the “fast” phases of N131V and D124N mutants, (2) they have reciprocal counterparts in the “slow” kinetic spectra in these mutants, and (3) they are absent in “fast” kinetic spectra of the E278Q mutant. Moreover, the double-difference spectra between the first two mutants and E278Q revealed more IR bands that may belong to the proton-loading site protolytic transitions. From these results, it is assumed that several polar residues and/or water molecule cluster(s) share a proton as a proton-loading site. This site can be propionate itself (holding only a fraction of H+), His403, and/or water cluster(s).

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