scholarly journals Time-Resolved Single-Step Protease Activity Quantification Using Nanoplasmonic Resonator Sensors

ACS Nano ◽  
2010 ◽  
Vol 4 (2) ◽  
pp. 978-984 ◽  
Author(s):  
Cheng Sun ◽  
Kai-Hung Su ◽  
Jason Valentine ◽  
Yazmin T. Rosa-Bauza ◽  
Jonathan A. Ellman ◽  
...  
Keyword(s):  
Protease Activity ◽  
Single Step ◽  
Time Resolved ◽  
Activity Quantification

Lifetime Measurements of Several S, P, and D States of Thallium in a Glow Discharge by Single-Step and Two-Step Laser-Excited Fluorescence

2008 ◽  
Vol 62 (1) ◽  
pp. 78-85 ◽  
Author(s):  
N. Taylor ◽  
N. Omenetto ◽  
B. W. Smith ◽  
J. D. Winefordner
Keyword(s):  
Glow Discharge ◽  
Laser Pulse ◽  
Metastable State ◽  
Decay Curve ◽  
Single Step ◽  
Metastable Level ◽  
Applied Current ◽  
Lifetime Measurements ◽  
Time Resolved ◽  
Current Dependence

The lifetimes of several states in a thallium see-through hollow cathode discharge, or galvatron, are obtained to characterize its potential as an atomic line filter. The lifetimes of the thallium 6 2D3/2, 6 2D5/2, and 7 2S1/2 states are measured by time-resolved single-step laser-excited fluorescence by use of a 276.787 nm laser pulse or a 535.046 nm laser pulse and measuring the resulting fluorescence waveform at the appropriate wavelength. Values of 6.4 ± 0.1, 7.5 ± 1.1, and 7.7 ± 0.2 ns were obtained for the 6 2D3/2, 6 2D5/2, and 7 2S1/2 states, respectively, which agree with values obtained by previous authors, as well as calculated values. No current dependence was observed for each of these states. The lifetime of the long-lived thallium 6 2P3/2° metastable state was measured by two-step laser-excited fluorescence at various applied currents. The metastable level was pumped by a 276.787 nm laser pulse, and a temporally delayed 535.046 nm laser pulse interrogated the population of the metastable state. Relating the fluorescence intensity to the population of the metastable state as a function of delay time yielded a decay curve for the 6 2P3/2° metastable state. Values of 2.1 ± 0.2, 2.8 ± 0.1, 3.1 ± 0.3, 3.8 ± 0.4, and 4.8 ± 0.6 μs were found for applied currents of 14.0, 12.0, 10.0, 8.0, and 6.0 mA, respectively. The resulting lifetimes for the 6 2P3/2° metastable state clearly show a dependence on the applied current and are expected to be due to collisions with the wall of the cathode, as well as a contribution due to collisions with electrons.

Time-Resolved Fluorescence-Based Assay for the Determination of Alkaline Phosphatase Activity and Application to the Screening of Its Inhibitors

2007 ◽  
Vol 13 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Petra Schrenkhammer ◽  
Ina C. Rosnizeck ◽  
Axel Duerkop ◽  
Otto S. Wolfbeis ◽  
Michael Schäferling
Keyword(s):  
Alkaline Phosphatase ◽  
Limit Of Detection ◽  
Single Step ◽  
Central Metal ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
State Measurement ◽  
Steady State Measurement ◽  
Enzyme Alkaline Phosphatase

A single-step end point method is presented for determination of the activity of the enzyme alkaline phosphatase (ALP) using the effect of enhancement of fluorescence of the easily accessible europium(III)-tetracycline 3:1 complex (Eu3TC). Its luminescence, peaking at 616 nm if excited at 405 nm, is enhanced by a factor of 2.5 in the presence of phosphate. Phenyl phosphate was used as a substrate that is enzymatically hydrolyzed to form phenol and phosphate. The latter coordinates to Eu3TC and enhances its luminescence intensity as a result of the displacement of water from the inner coordination sphere of the central metal. The assay is performed in a time-resolved (gated) mode, which is shown to yield larger signal changes than steady-state measurement of fluorescence. The limit of detection for ALP is 4 µmol L—1. Based on this scheme, a model assay for theophylline as inhibitor for ALP was developed with a linear range from 14 to 68 µmol L— 1 of theophylline. ( Journal of Biomolecular Screening 2008:9-16)

In situ time-resolved HEROS study of Pt electronic structure during regenerative H2-O2 cycles

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Jacinto Sá
Keyword(s):  
Electronic Structure ◽  
Energy Resolution ◽  
Time Resolution ◽  
Electronic States ◽  
Reduction Process ◽  
High Energy ◽  
Single Step ◽  
High Energy Resolution ◽  
Time Resolved

AbstractWe report an in situ time-resolved high-energy resolution off-resonant spectroscopy (HEROS) study with unprecedented 100 ms time resolution revealing the unoccupied electronic states of platinum during regenerative oxidation and reduction cycles. The study depicted a slowed oxidation step in comparison with reduction. The oxidation cycle is composed of two characteristic stages, namely adsorption of dissociated oxygen followed by partial oxidation of Pt subsurface. Besides improved temporal resolution of the experiment, the detected reduction process of platinum showed no intermediate features and was completed in a single step within a few seconds.

Ligand mediated excited state carrier relaxation dynamics of Cd1−xZnxSe1−ySy NCs derived from bile salts

2017 ◽  
Vol 5 (20) ◽  
pp. 4977-4984 ◽  
Author(s):  
Sayantan Chatterjee ◽  
Uday Maitra
Keyword(s):  
Excited State ◽  
Bile Acid ◽  
Bile Salts ◽  
Single Step ◽  
Relaxation Dynamics ◽  
Time Resolved ◽  
Carrier Relaxation ◽  
Time Resolved Spectroscopy ◽  
Carrier Relaxation Dynamics

Bile acid derived cadmium and zinc precursors were utilized for an efficient and single step synthesis of Cd1−xZnxSe1−ySy NCs. Different capping ligand induced carrier relaxation dynamics of the NCs using time resolved spectroscopy was also studied.

scholarly journals Protease Substrate-Independent Universal Assay for Monitoring Digestion of Native Unmodified Proteins

2021 ◽  
Vol 22 (12) ◽  
pp. 6362
Author(s):  
Emmiliisa Vuorinen ◽  
Salla Valtonen ◽  
Nazia Hassan ◽  
Randa Mahran ◽  
Huda Habib ◽  
...  
Keyword(s):  
Protease Activity ◽  
Microtiter Plate ◽  
Probe Method ◽  
Label Free ◽  
Target Class ◽  
Signaling Mechanism ◽  
Peptide Bonds ◽  
Time Resolved ◽  
Drug Candidates ◽  
Catalytic Function

Proteases are a group of enzymes with a catalytic function to hydrolyze peptide bonds of proteins. Proteases regulate the activity, signaling mechanism, fate, and localization of many proteins, and their dysregulation is associated with various pathological conditions. Proteases have been identified as biomarkers and potential therapeutic targets for multiple diseases, such as acquired immunodeficiency syndrome, cardiovascular diseases, osteoporosis, type 2 diabetes, and cancer, where they are essential to disease progression. Thus, protease inhibitors and inhibitor-like molecules are interesting drug candidates. To study proteases and their substrates and inhibitors, simple, rapid, and sensitive protease activity assays are needed. Existing fluorescence-based assays enable protease monitoring in a high-throughput compatible microtiter plate format, but the methods often rely on either molecular labeling or synthetic protease targets that only mimic the hydrolysis site of the true target proteins. Here, we present a homogenous, label-free, and time-resolved luminescence utilizing the protein-probe method to assay proteases with native and denatured substrates at nanomolar sensitivity. The developed protein-probe method is not restricted to any single protein or protein target class, enabling digestion and substrate fragmentation studies with the natural unmodified substrate proteins. The versatility of the assay for studying protease targets was shown by monitoring the digestion of a substrate panel with different proteases. These results indicate that the protein-probe method not only monitors the protease activity and inhibition, but also studies the substrate specificity of individual proteases.

Production of an extracellular trypsin-like protease by the fungal plant pathogenVerticillium dahliae

1997 ◽  
Vol 43 (3) ◽  
pp. 227-233 ◽  
Author(s):  
Katherine F. Dobinson ◽  
Nicolas Lecomte ◽  
George Lazarovits
Keyword(s):  
Serine Protease ◽  
Protease Activity ◽  
Pathogenic Fungus ◽  
Skim Milk ◽  
Exchange Chromatography ◽  
Single Step ◽  
Protein Source ◽  
Amino Acid Sequence Analysis ◽  
Serine Protease Activity ◽  
Terminal Amino

The plant pathogenic fungus Verticillium dahliae produced extracellular alkaline protease activity when grown in liquid medium supplemented with a protein source. A serine protease was purified 80-fold in a single step, using cation-exchange chromatography, from the filtrate of cultures grown with skim milk as a protein source. N-terminal amino acid sequence analysis of the 30-kDa protein (VDP30) that copurified with the serine protease activity suggested that VDP30 is a trypsin-like protein. The purified enzyme hydrolyzed the synthetic substrate Nα-benzoyl-DL-arginine p-nitroanilide hydrochloride (BAPNA), and the activity on BAPNA was inhibited by leupeptin, further verifying the trypsin-like nature of the enzyme.Key words: proteinase, phytopathogen, verticillium wilt, wilt fungi.

scholarly journals The statistical challenge of finding spontaneous changes in functional connectivity in high-dimensional fMRI data

2020 ◽  
Author(s):  
Diego Vidaurre
Keyword(s):  
Functional Connectivity ◽  
Information Transfer ◽  
Brain Regions ◽  
Single Step ◽  
High Dimensional ◽  
Fast Time ◽  
Time Varying ◽  
Time Resolved ◽  
Neuronal Communication ◽  
Bayesian Mixture

An important question in neuroscience is whether or not we can interpret spontaneous variations in the pattern of correlation between brain areas, which we refer to as functional connectivity or FC , as an index of dynamic neuronal communication in fMRI . That is, can we measure time-varying FC reliably? And, if so, can FC reflect information transfer between brain regions at relatively fast-time scales? Answering these questions in practice requires dealing with the statistical challenge of having high-dimensional data and a comparatively lower number of time points or volumes. A common strategy is to use PCA to reduce the dimensionality of the data, and then apply some model, such as the hidden Markov model (HMM) or a Bayesian mixture of distributions, to find a set of distinct FC patterns or states. The distinct spatial properties of these FC states together with the time resolved switching between them offer a flexible description of time-varying FC . In this work, we show that in this context PCA can suffer from systematic biases and loss of sensitivity for the purposes of finding time-varying FC . To get around these issues, we propose a novel variety of the HMM, the HMM- PCA , where the states are themselves PCA decompositions. Since PCA is based on the data covariance, the state-specific PCA decompositions reflect distinct patterns of FC . We show, theoretically and empirically, that fusing dimensionality reduction and time-varying FC estimation in one single step can avoid these problems and outperform alternative approaches, eventually facilitating the quantification of transient communication in the brain.

scholarly journals A new model for simultaneous dimensionality reduction and time-varying functional connectivity estimation

2021 ◽  
Vol 17 (4) ◽  
pp. e1008580
Author(s):  
Diego Vidaurre
Keyword(s):  
Functional Connectivity ◽  
Dimensionality Reduction ◽  
Information Transfer ◽  
Brain Regions ◽  
Single Step ◽  
Fast Time ◽  
Time Varying ◽  
Time Resolved ◽  
Neuronal Communication ◽  
Common Strategy

An important question in neuroscience is whether or not we can interpret spontaneous variations in the pattern of correlation between brain areas, which we refer to as functional connectivity or FC, as an index of dynamic neuronal communication in fMRI. That is, can we measure time-varying FC reliably? And, if so, can FC reflect information transfer between brain regions at relatively fast-time scales? Answering these questions in practice requires dealing with the statistical challenge of having high-dimensional data and a comparatively lower number of time points or volumes. A common strategy is to use PCA to reduce the dimensionality of the data, and then apply some model, such as the hidden Markov model (HMM) or a mixture model of Gaussian distributions, to find a set of distinct FC patterns or states. The distinct spatial properties of these FC states together with the time-resolved switching between them offer a flexible description of time-varying FC. In this work, I show that in this context PCA can suffer from systematic biases and loss of sensitivity for the purposes of finding time-varying FC. To get around these issues, I propose a novel variety of the HMM, named HMM-PCA, where the states are themselves PCA decompositions. Since PCA is based on the data covariance, the state-specific PCA decompositions reflect distinct patterns of FC. I show, theoretically and empirically, that fusing dimensionality reduction and time-varying FC estimation in one single step can avoid these problems and outperform alternative approaches, facilitating the quantification of transient communication in the brain.

Lanthanide-Based Protease Activity Sensors for Time-Resolved Fluorescence Measurements

2008 ◽  
Vol 130 (44) ◽  
pp. 14376-14377 ◽  
Author(s):  
Shin Mizukami ◽  
Kazuhiro Tonai ◽  
Masahiro Kaneko ◽  
Kazuya Kikuchi
Keyword(s):  
Protease Activity ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Fluorescence Measurements ◽  
Activity Sensors

Energy migration and transfer in styrene-containing polymers with inhibited excimer formation

1995 ◽  
Vol 73 (11) ◽  
pp. 2015-2020 ◽  
Author(s):  
Kenneth P. Ghiggino ◽  
Trevor A. Smith ◽  
David J. Haines ◽  
Gerard J. Wilson
Keyword(s):  
Energy Transfer ◽  
Energy Transport ◽  
Single Step ◽  
Energy Migration ◽  
Spectroscopic Techniques ◽  
Time Resolved ◽  
Polymer Systems ◽  
Excimer Formation ◽  
Dipole Energy ◽  
Fluorescence Energy

Steady-state and time-resolved fluorescence spectroscopic techniques have been used to examine energy transfer and the migration of photoexcitation energy in styrene-containing polymer systems in which excimer formation is inhibited. In particular, copolymers of styrene and p-tert-butyl styrene with acenaphthylene (ACE) acceptor chromophores have been studied. Energy transfer efficiencies between styrene moieties and ACE chromophores incorporated as in-chain traps have been determined and are higher than predicted for a single-step Förster dipole–dipole energy transfer process. The results are discussed with reference to the possible mechanisms for excitation energy transport in these polymers. Keywords: polystyrene fluorescence, energy migration, energy transfer, excimer.

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