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Micro-mechanical response and power-law exponents from the longitudinal fluctuations of F-actin solutions

We investigate the local fluctuations of filamentous actin (F-actin), with a focus on the skeletal thin filament, using single-particle optical trapping interferometry. This experimental technique allows us to detect the Brownian motion of a tracer bead immersed in a complex fluid with nanometric re...

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Autores principales: Domínguez-García, Pablo, Pinto, Jose R., Akrap, Ana, Jeney, Sylvia
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society of Chemistry 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10208217/
https://www.ncbi.nlm.nih.gov/pubmed/37165665
http://dx.doi.org/10.1039/d2sm01445a
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author Domínguez-García, Pablo
Pinto, Jose R.
Akrap, Ana
Jeney, Sylvia
author_facet Domínguez-García, Pablo
Pinto, Jose R.
Akrap, Ana
Jeney, Sylvia
author_sort Domínguez-García, Pablo
collection PubMed
description We investigate the local fluctuations of filamentous actin (F-actin), with a focus on the skeletal thin filament, using single-particle optical trapping interferometry. This experimental technique allows us to detect the Brownian motion of a tracer bead immersed in a complex fluid with nanometric resolution at the microsecond time-scale. The mean square displacement, loss modulus, and velocity autocorrelation function (VAF) of the trapped microprobes in the fluid follow power-law behaviors, whose exponents can be determined in the short-time/high-frequency regime over several decades. We obtain 7/8 subdiffusive power-law exponents for polystyrene depleted microtracers at low optical trapping forces. Microrheologically, the elastic modulus of these suspensions is observed to be constant up to the limit of high frequencies, confirming that the origin of this subdiffusive exponent is the local longitudinal fluctuations of the polymers. Deviations from this value are measured and discussed in relation to the characteristic length scales of these F-actin networks and probes’ properties, and also in connection with the different power-law exponents detected in the VAFs. Finally, we observed that the thin filament, composed of tropomyosin (Tm) and troponin (Tn) coupled to F-actin in the presence of Ca(2+), shows exponent values less dispersed than that of F-actin alone, which we interpret as a micro-measurement of the filament stabilization.
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spelling pubmed-102082172023-05-25 Micro-mechanical response and power-law exponents from the longitudinal fluctuations of F-actin solutions Domínguez-García, Pablo Pinto, Jose R. Akrap, Ana Jeney, Sylvia Soft Matter Chemistry We investigate the local fluctuations of filamentous actin (F-actin), with a focus on the skeletal thin filament, using single-particle optical trapping interferometry. This experimental technique allows us to detect the Brownian motion of a tracer bead immersed in a complex fluid with nanometric resolution at the microsecond time-scale. The mean square displacement, loss modulus, and velocity autocorrelation function (VAF) of the trapped microprobes in the fluid follow power-law behaviors, whose exponents can be determined in the short-time/high-frequency regime over several decades. We obtain 7/8 subdiffusive power-law exponents for polystyrene depleted microtracers at low optical trapping forces. Microrheologically, the elastic modulus of these suspensions is observed to be constant up to the limit of high frequencies, confirming that the origin of this subdiffusive exponent is the local longitudinal fluctuations of the polymers. Deviations from this value are measured and discussed in relation to the characteristic length scales of these F-actin networks and probes’ properties, and also in connection with the different power-law exponents detected in the VAFs. Finally, we observed that the thin filament, composed of tropomyosin (Tm) and troponin (Tn) coupled to F-actin in the presence of Ca(2+), shows exponent values less dispersed than that of F-actin alone, which we interpret as a micro-measurement of the filament stabilization. The Royal Society of Chemistry 2023-04-28 /pmc/articles/PMC10208217/ /pubmed/37165665 http://dx.doi.org/10.1039/d2sm01445a Text en This journal is © The Royal Society of Chemistry https://creativecommons.org/licenses/by-nc/3.0/
spellingShingle Chemistry
Domínguez-García, Pablo
Pinto, Jose R.
Akrap, Ana
Jeney, Sylvia
Micro-mechanical response and power-law exponents from the longitudinal fluctuations of F-actin solutions
title Micro-mechanical response and power-law exponents from the longitudinal fluctuations of F-actin solutions
title_full Micro-mechanical response and power-law exponents from the longitudinal fluctuations of F-actin solutions
title_fullStr Micro-mechanical response and power-law exponents from the longitudinal fluctuations of F-actin solutions
title_full_unstemmed Micro-mechanical response and power-law exponents from the longitudinal fluctuations of F-actin solutions
title_short Micro-mechanical response and power-law exponents from the longitudinal fluctuations of F-actin solutions
title_sort micro-mechanical response and power-law exponents from the longitudinal fluctuations of f-actin solutions
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10208217/
https://www.ncbi.nlm.nih.gov/pubmed/37165665
http://dx.doi.org/10.1039/d2sm01445a
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