Time-resolved observation of protein allosteric communication

Allostery represents a fundamental mechanism of biological regulation that is mediated via long-range communication between distant protein sites. Although little is known about the underlying dynamical process, recent time-resolved infrared spectroscopy experiments on a photoswitchable PDZ domain (PDZ2S) have indicated that the allosteric transition occurs on multiple timescales. Here, using extensive nonequilibrium molecular dynamics simulations, a time-dependent picture of the allosteric communication in PDZ2S is developed. The simulations reveal that allostery amounts to the propagation of structural and dynamical changes that are genuinely nonlinear and can occur in a nonlocal fashion. A dynamic network model is constructed that illustrates the hierarchy and exceeding structural heterogeneity of the process. In compelling agreement with experiment, three physically distinct phases of the time evolution are identified, describing elastic response (≲0.1 ns), inelastic reorganization (∼100 ns), and structural relaxation (≳1μs). Issues such as the similarity to downhill folding as well as the interpretation of allosteric pathways are discussed.

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Time-resolved infrared spectroscopy

Physics Subject Headings (PhySH) ◽

10.29172/4b7bcf858b1f409b8d0adae40b4e3b6e ◽

2018 ◽

Keyword(s):

Infrared Spectroscopy ◽

Time Resolved ◽

Time Resolved Infrared Spectroscopy

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The Character of Low-Lying Excited States of Mixed-Ligand Metal Carbonyls. TD-DFT and CASSCF/CASPT2 Study of [W(CO)4L] (L = ethylenediamine, N,N'-dialkyl-1,4-diazabutadiene) and [W(CO)5L] (L = pyridine, 4-cyanopyridine)

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20030089 ◽

2003 ◽

Vol 68 (1) ◽

pp. 89-104 ◽

Cited By ~ 6

Author(s):

Stanislav Záliš ◽

Antonín Vlček ◽

Chantal Daniel

Keyword(s):

Excited States ◽

Substitution Effect ◽

Electronic Transitions ◽

Ligand Field ◽

Metal Carbonyls ◽

Electron Density Redistribution ◽

Time Resolved ◽

Model Complex ◽

Td Dft ◽

Time Resolved Infrared Spectroscopy

This contribution presents the results of the TD-DFT and CASSCF/CASPT2 calculations on [W(CO)4(MeDAB)] (MeDAB = N,N'-dimethyl-1,4-diazabutadiene), [W(CO)4(en)] (en = ethylenediamine), [W(CO)5(py)] (py = pyridine) and [W(CO)5(CNpy)] (CNpy = 4-cyanopyridine) complexes. Contrary to the textbook interpretation, calculations on the model complex [W(CO)4(MeDAB)] and [W(CO)5(CNpy)] show that the lowest W→MeDAB and W→CNpy MLCT excited states are immediately followed in energy by several W→CO MLCT states, instead of ligand-field (LF) states. The lowest-lying excited states of [W(CO)4(en)] system were characterized as W(COeq)2→COax CT excitations, which involve a remarkable electron density redistribution between axial and equatorial CO ligands. [W(CO)5(py)] possesses closely-lying W→CO and W→py MLCT excited states. The calculated energies of these states are sensitive to the computational methodology used and can be easily influenced by a substitution effect. The calculated shifts of [W(CO)4(en)] stretching CO frequencies due to excitation are in agreement with picosecond time-resolved infrared spectroscopy experiments and confirm the occurrence of low-lying M→CO MLCT transitions. No LF electronic transitions were found for either of the complexes studied in the region up to 4 eV.

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Helmet Phthalocyaninato Iron Complex as a Primary Drier for Alkyd Paints

Materials ◽

10.3390/ma14051220 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1220

Author(s):

Jan Honzíček ◽

Eliška Matušková ◽

Štěpán Voneš ◽

Jaromír Vinklárek

Keyword(s):

Catalytic Performance ◽

Mechanical Tests ◽

Iron Complex ◽

Kinetic Measurements ◽

Time Resolved ◽

Strong Activity ◽

Vis Spectroscopy ◽

Order Of Magnitude ◽

Transparent Coatings ◽

Time Resolved Infrared Spectroscopy

This study describes the catalytic performance of an iron(III) complex bearing a phthalocyaninato-like ligand in two solvent-borne and two high-solid alkyd binders. Standardized mechanical tests revealed strong activity, which appeared in particular cases at concentrations about one order of magnitude lower than in the case of cobalt(II) 2-ethylhexanoate, widespread used in paint-producing industry. The effect of the iron(III) compound on autoxidation process, responsible for alkyd curing, was quantified by kinetic measurements by time-resolved infrared spectroscopy and compared with several primary driers. Effect of the drier concentration on coloration of transparent coatings was determined by UV–Vis spectroscopy.

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A quantum cascade laser setup for studying irreversible photoreactions in H2O with nanosecond resolution and microlitre consumption

Physical Chemistry Chemical Physics ◽

10.1039/d0cp03164j ◽

2020 ◽

Vol 22 (45) ◽

pp. 26459-26467

Author(s):

Jessica L. Klocke ◽

Tilman Kottke

Keyword(s):

Infrared Spectroscopy ◽

Quantum Cascade Laser ◽

Time Resolved ◽

Quantum Cascade ◽

Time Resolved Infrared Spectroscopy ◽

Laser Setup

Flavin photoreduction in H2O is elucidated by developing a quantum cascade laser setup for time-resolved infrared spectroscopy on irreversible reactions.

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