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UID:0-854@lptms.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20230221T110000
DTEND;TZID=Europe/Paris:20230221T120000
DTSTAMP:20230130T112711Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
 s-igor-bodrenko-cagliari-university/
SUMMARY:Séminaire du LPTMS : Igor Bodrenko (Cagliari University) - Salle d
 es séminaires du FAST et du LPTMS\, bâtiment Pascal n°530 - 21 Fév 23 
 11:00
DESCRIPTION:Diffusion of flexible molecules through flexible nanochannels:
  the concept of size.\nIgor Bodrenko (Cagliari University)\nHybrid: onsit
 e seminar + zoom.\n\nhttps://cnrs.zoom.us/j/96968433581?pwd=UStqem83UzFYTF
 F4ODlSclExSGZXZz09\n\nFlexible molecules can adopt their shape and diffuse
  through nanopores which are significantly more tight than the average dim
 ension of the molecules in bulk solution.  This phenomenon is known for p
 olymers which can unfold\, translocate through a tight pore and then refol
 d again [1]. Recently\, we have demonstrated that the effect of molecule/p
 ore flexibility is of crucial importance for the penetration of biological
 ly related small molecules\, like nutrients and drugs\, into bacterial cel
 ls [2\,3].\n\nHere\, we will discuss a statistical approach [3] which allo
 ws one to separate the effect of steric hindrance from other the molecule-
 pore-solute interactions. We will also  define the concepts of the molecu
 le and the pore size adequate for the diffusive transport through nanopore
 s. The average cross sectional area profile along the channel and the aver
 age minimal projection area of the molecule are the two major quantities d
 etermining the steric part of the free energy barrier for the translocatio
 n of the particle in the case of a small rigid particle and a large rigid 
 channel. In this case\, the description is reduced to the Fick-Jacobs mode
 l. However\, the flexibility of the channel's cross section and that of th
 e molecule's size play a crucial role when a large molecule goes through a
  narrow channel. We treat the flexibility in terms of the equilibrium fluc
 tuations of the pore and of the molecule\, independently.\n\nFor the case 
 of gaussian fluctuations\, we derived simple analytical expressions for th
 e steric free energy barrier and for the permeability coefficient of the p
 ore. The model is compared with the all-atom MD simulations of the transpo
 rt of Van-der-Waals spheres of various radii through a biological nanochan
 nel\, as well as of the transport of real molecules through artificial rig
 id pores of different radii. \n\n[1] M. Muthukumar\, “Polymer Transloca
 tion”\, CRC Press\, 2011\n\n[2] Julia Vergalli\, et.al. \, “Porins and
  small-mol-ecule translocation across the outer membrane of Gram-negative 
 bacteria”\,  Nature Reviews Microbiology\, 18\,164–176 (2020)\; DOI: 
 10.1038/s41579-019-0294-2\n\n[3] Igor V Bodrenko et.al\, “Diffusion of l
 arge particles through small pores: From  entropic to enthalpic transport
 ”\, J. Chem. Phys.\, 150 (2019) 211102\; DOI: 10.1063/1.5098868
CATEGORIES:seminars
LOCATION:Salle des séminaires du FAST et du LPTMS\, bâtiment Pascal n°53
 0\, rue André Riviere\, Orsay\, 91405\, France
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=rue André Riviere\, Orsay\
 , 91405\, France;X-APPLE-RADIUS=100;X-TITLE=Salle des séminaires du FAST 
 et du LPTMS\, bâtiment Pascal n°530:geo:0,0
END:VEVENT
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TZID:Europe/Paris
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DTSTART:20221030T020000
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