scholarly journals Exponential and Power-Law Kinetics in Single-Molecule Fluorescence Intermittency†

2004 ◽  
Vol 108 (29) ◽  
pp. 10445-10450 ◽  
Author(s):  
Matthias Haase ◽  
Christian G. Hübner ◽  
E. Reuther ◽  
A. Herrmann ◽  
K. Müllen ◽  
...  
Keyword(s):  
Single Molecule ◽  
Power Law ◽  
Single Molecule Fluorescence ◽  
Power Law Kinetics ◽  
Fluorescence Intermittency

scholarly journals Slow domain reconfiguration causes power-law kinetics in a two-state enzyme

2018 ◽  
Vol 115 (3) ◽  
pp. 513-518 ◽  
Author(s):  
Iris Grossman-Haham ◽  
Gabriel Rosenblum ◽  
Trishool Namani ◽  
Hagen Hofmann
Keyword(s):  
Free Energy ◽  
Single Molecule ◽  
Power Law ◽  
Energy Landscape ◽  
Rate Equations ◽  
Free Energy Landscape ◽  
Closed Domain ◽  
Single Molecule Fret ◽  
Power Law Kinetics ◽  
Interdomain Interactions

Protein dynamics are typically captured well by rate equations that predict exponential decays for two-state reactions. Here, we describe a remarkable exception. The electron-transfer enzyme quiescin sulfhydryl oxidase (QSOX), a natural fusion of two functionally distinct domains, switches between open- and closed-domain arrangements with apparent power-law kinetics. Using single-molecule FRET experiments on time scales from nanoseconds to milliseconds, we show that the unusual open-close kinetics results from slow sampling of an ensemble of disordered domain orientations. While substrate accelerates the kinetics, thus suggesting a substrate-induced switch to an alternative free energy landscape of the enzyme, the power-law behavior is also preserved upon electron load. Our results show that the slow sampling of open conformers is caused by a variety of interdomain interactions that imply a rugged free energy landscape, thus providing a generic mechanism for dynamic disorder in multidomain enzymes.

scholarly journals Field-Controlled Charge Separation in a Conductive Matrix at the Single-Molecule Level: Toward Controlling Single-Molecule Fluorescence Intermittency

ACS Omega ◽  
2016 ◽  
Vol 1 (6) ◽  
pp. 1383-1392 ◽  
Author(s):  
Koen Kennes ◽  
Peter Dedecker ◽  
James A. Hutchison ◽  
Eduard Fron ◽  
Hiroshi Uji-i ◽  
...  
Keyword(s):  
Single Molecule ◽  
Charge Separation ◽  
Single Molecule Fluorescence ◽  
Single Molecule Level ◽  
Fluorescence Intermittency

scholarly journals Single Molecule Fluorescence Imaging and Blinking

2006 ◽  
Vol 46 (3) ◽  
pp. 164-168
Author(s):  
Hiroaki YOKOTA ◽  
Tetsuichi WAZAWA ◽  
Yoshiharu ISHII
Keyword(s):  
Fluorescence Imaging ◽  
Single Molecule ◽  
Single Molecule Fluorescence

scholarly journals Power-law behavior of transcription factor dynamics at the single-molecule level implies a continuum affinity model

2021 ◽  
Author(s):  
David A Garcia ◽  
Gregory Fettweis ◽  
Diego M Presman ◽  
Ville Paakinaho ◽  
Christopher Jarzynski ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Single Molecule ◽  
Power Law ◽  
Dwell Time ◽  
Specific Binding ◽  
Power Law Distribution ◽  
Single Molecule Level ◽  
Binding Behavior ◽  
Chromatin Template ◽  
Nuclear Domains

Abstract Single-molecule tracking (SMT) allows the study of transcription factor (TF) dynamics in the nucleus, giving important information regarding the diffusion and binding behavior of these proteins in the nuclear environment. Dwell time distributions obtained by SMT for most TFs appear to follow bi-exponential behavior. This has been ascribed to two discrete populations of TFs—one non-specifically bound to chromatin and another specifically bound to target sites, as implied by decades of biochemical studies. However, emerging studies suggest alternate models for dwell-time distributions, indicating the existence of more than two populations of TFs (multi-exponential distribution), or even the absence of discrete states altogether (power-law distribution). Here, we present an analytical pipeline to evaluate which model best explains SMT data. We find that a broad spectrum of TFs (including glucocorticoid receptor, oestrogen receptor, FOXA1, CTCF) follow a power-law distribution of dwell-times, blurring the temporal line between non-specific and specific binding, suggesting that productive binding may involve longer binding events than previously believed. From these observations, we propose a continuum of affinities model to explain TF dynamics, that is consistent with complex interactions of TFs with multiple nuclear domains as well as binding and searching on the chromatin template.

scholarly journals Single bacterial resolvases first exploit, then constrain intrinsic dynamics of the Holliday junction to direct recombination

2021 ◽  
Author(s):  
Sujay Ray ◽  
Nibedita Pal ◽  
Nils G Walter
Keyword(s):  
Cluster Analysis ◽  
Homologous Recombination ◽  
Single Molecule ◽  
Holliday Junction ◽  
Energetic Cost ◽  
Genomic Integrity ◽  
Dna Molecules ◽  
Single Molecule Fluorescence ◽  
And Cluster Analysis ◽  
Fluorescence Observation

Abstract Homologous recombination forms and resolves an entangled DNA Holliday Junction (HJ) crucial for achieving genetic reshuffling and genome repair. To maintain genomic integrity, specialized resolvase enzymes cleave the entangled DNA into two discrete DNA molecules. However, it is unclear how two similar stacking isomers are distinguished, and how a cognate sequence is found and recognized to achieve accurate recombination. We here use single-molecule fluorescence observation and cluster analysis to examine how prototypic bacterial resolvase RuvC singles out two of the four HJ strands and achieves sequence-specific cleavage. We find that RuvC first exploits, then constrains the dynamics of intrinsic HJ isomer exchange at a sampled branch position to direct cleavage toward the catalytically competent HJ conformation and sequence, thus controlling recombination output at minimal energetic cost. Our model of rapid DNA scanning followed by ‘snap-locking’ of a cognate sequence is strikingly consistent with the conformational proofreading of other DNA-modifying enzymes.

scholarly journals Low-Light Photodetectors for Fluorescence Microscopy

2021 ◽  
Vol 11 (6) ◽  
pp. 2773
Author(s):  
Hiroaki Yokota ◽  
Atsuhito Fukasawa ◽  
Minako Hirano ◽  
Toru Ide
Keyword(s):  
Fluorescence Microscopy ◽  
Fluorescence Imaging ◽  
Single Molecule ◽  
Science Studies ◽  
Single Photon ◽  
Laser Scanning Microscopy ◽  
Oxide Semiconductor ◽  
Wide Field ◽  
Single Molecule Fluorescence ◽  
Low Light

Over the years, fluorescence microscopy has evolved and has become a necessary element of life science studies. Microscopy has elucidated biological processes in live cells and organisms, and also enabled tracking of biomolecules in real time. Development of highly sensitive photodetectors and light sources, in addition to the evolution of various illumination methods and fluorophores, has helped microscopy acquire single-molecule fluorescence sensitivity, enabling single-molecule fluorescence imaging and detection. Low-light photodetectors used in microscopy are classified into two categories: point photodetectors and wide-field photodetectors. Although point photodetectors, notably photomultiplier tubes (PMTs), have been commonly used in laser scanning microscopy (LSM) with a confocal illumination setup, wide-field photodetectors, such as electron-multiplying charge-coupled devices (EMCCDs) and scientific complementary metal-oxide-semiconductor (sCMOS) cameras have been used in fluorescence imaging. This review focuses on the former low-light point photodetectors and presents their fluorescence microscopy applications and recent progress. These photodetectors include conventional PMTs, single photon avalanche diodes (SPADs), hybrid photodetectors (HPDs), in addition to newly emerging photodetectors, such as silicon photomultipliers (SiPMs) (also known as multi-pixel photon counters (MPPCs)) and superconducting nanowire single photon detectors (SSPDs). In particular, this review shows distinctive features of HPD and application of HPD to wide-field single-molecule fluorescence detection.

Sign in / Sign up

Export Citation Format

Share Document