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Mostajabi Sarhangi S, Matyushov DV. Remarkable Insensitivity of Protein Diffusion to Protein Charge. J Phys Chem Lett 2024:9502-9508. [PMID: 39259029 DOI: 10.1021/acs.jpclett.4c02062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
Friction to translational diffusion of ionic particles in polar liquids should scale linearly with the squared ion charge, according to standard theories. Substantial slowing of translational diffusion is expected for proteins in water. In contrast, our simulations of charge mutants of green fluorescent proteins in water show remarkable insensitivity of the translational diffusion constant to protein's charge in the range of charges between -29 and +35. The friction coefficient is given as a product of the force variance and the memory function relaxation time. We find remarkably accurate equality between the variance of the electrostatic force and the negative cross-correlation of the electrostatic and van der Waals forces. The charge invariance of the diffusion constant is a combined effect of the force variance and relaxation time invariances with the protein charge. The temperature dependence of the protein diffusion constant is highly non-Arrhenius, with a fragile-to-strong crossover at the glass transition.
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Affiliation(s)
- Setare Mostajabi Sarhangi
- Department of Physics, Arizona State University, PO Box 871504, Tempe, Arizona 85287-1504, United States
| | - Dmitry V Matyushov
- School of Molecular Sciences and Department of Physics, Arizona State University, PO Box 871504, Tempe, Arizona 85287-1504, United States
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Shrestha D, Ou J, Rogers A, Jereb A, Okyere D, Chen J, Wang Y. Bacterial mobility and motility in porous media mimicked by microspheres. Colloids Surf B Biointerfaces 2023; 222:113128. [PMID: 36630770 DOI: 10.1016/j.colsurfb.2023.113128] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/19/2022] [Accepted: 01/03/2023] [Indexed: 01/05/2023]
Abstract
Bacterial motion in porous media is essential for their survival, proper functioning, and various applications. Here we investigated the motion of Escherichia coli bacteria in microsphere-mimicked porous media. We observed reduced bacterial velocity and enhanced directional changes of bacteria as the density of microspheres increased, while such changes happened mostly around the microspheres and due to the collisions with the microspheres. More importantly, we established and quantified the correlation between the bacterial trapping in porous media and the geometric confinement imposed by the microspheres. In addition, numerical simulations showed that the active Brownian motion model in the presence of microspheres resulted in bacterial motion that are consistent with the experimental observations. Our study suggested that it is important to distinguish the ability of bacteria to move easily - bacterial mobility - from the ability of bacteria to move independently - bacteria motility. Our results showed that bacterial motility remains similar in porous media, but bacterial mobility was significantly affected by the pore-scale confinement.
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Affiliation(s)
- Diksha Shrestha
- Department of Physics, University of Arkansas, Fayetteville 72701, AR, USA; Cell and Molecular Biology Program, University of Arkansas, Fayetteville 72701, AR, USA
| | - Jun Ou
- School of Engineering, California State Polytechnic University Humboldt, Arcata 95521, CA, USA; Mechanical Engineering Program, California State Polytechnic University Humboldt, Arcata 95521, CA, USA
| | - Ariel Rogers
- Department of Physics, University of Arkansas, Fayetteville 72701, AR, USA
| | - Amani Jereb
- Department of Physics, University of Arkansas, Fayetteville 72701, AR, USA; Cell and Molecular Biology Program, University of Arkansas, Fayetteville 72701, AR, USA
| | - Deborah Okyere
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville 72701, AR, USA; Materials Science and Engineering Program, University of Arkansas, Fayetteville 72701, AR, USA
| | - Jingyi Chen
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville 72701, AR, USA; Materials Science and Engineering Program, University of Arkansas, Fayetteville 72701, AR, USA
| | - Yong Wang
- Department of Physics, University of Arkansas, Fayetteville 72701, AR, USA; Cell and Molecular Biology Program, University of Arkansas, Fayetteville 72701, AR, USA; Materials Science and Engineering Program, University of Arkansas, Fayetteville 72701, AR, USA.
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