Hi, "3000 water molecule per lipids per second" corresponds to 0.000384 water molecules transferred across the membrane per nano second (assume the system contains 128 lipids). It seems water translocation should not be observed in a simulation of 10 ns, but I am not sure. And I only find one reference paper(Biophysical Journal, Volume 96, 2009, pg4493–4501) about the water translocation across the membrane, in which a asymmetric membrane is used.
I also have similar observations for my protein-membrane system. I observed 10~15 times water translocation arosss the membrane during 100 ns simulation when my protein adsorbed on the membrane. I am wondering these water translocation is normal in all-atom simulations or they are due to the protein-induced membrane deformation? Any comment is highly appreciated, thank you! best regards, Jianguo ________________________________ From: Itamar Kass <[email protected]> To: Discussion list for GROMACS users <[email protected]> Sent: Thursday, 17 February 2011 07:20:19 Subject: Re: [gmx-users] Protein-membrane system Dear Aldo, It is totally OK to see water molecules within the bilayer, both in simulations and real life. If I am not totally wrong, 3000 water molecule per lipids per second are being transferred across the bilayer without any protein involvement. If your system is stable, the lipids density profile seems OK as well as its the thickness, you are fine. Cheers, Itamar. On 17/02/11 5:48 AM, Justin A. Lemkul wrote: > > Aldo Segura wrote: >> Dear gmx-users, >> >> I completed a MD (10 ns) of my protein-membrane system. When I perform a >> visual >>inspection (VMD) of md_0_1.gro file I observed a few water molecules within >>the >>bilayer. In previous steps (e.g. equilibration) this was not observed. Could >>be >>expected such behavior? > > Membrane protein systems take a long time (tens of ns or maybe more) to >equilibrate, so some water may drift in and out during the initial few ns as >voids in the lipids open and close. Nothing to worry about, unless for some >reason they persist out past the expected equilibration time. > > -Justin > >> >> Best regards, >> >> >> *//* >> >> */============================== ========= >> Aldo Segura-Cabrera >> Laboratorio de Bioinformática >> Centro de Biotecnología Genómica >> Instituto Politécnico Nacional >> Blvd. Del Maestro esquina Elías Piña, 88710 >> Reynosa, Tamaulipas, México. >> (899)9243627 ext. 87747 >> e-mail: [email protected] <mailto:[email protected]>; [email protected] >><mailto:[email protected]> >> ============================== ===========/* >> >> >> >> > -- "In theory, there is no difference between theory and practice. But, in practice, there is." - Jan L.A. van de Snepscheut =========================================== | Itamar Kass, Ph.D. | Postdoctoral Research Fellow | | Department of Biochemistry and Molecular Biology | Building 77 Clayton Campus | Wellington Road | Monash University, | Victoria 3800 | Australia | | Tel: +61 3 9902 9376 | Fax: +61 3 9902 9500 | E-mail: [email protected] ============================================ -- gmx-users mailing list [email protected] http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to [email protected]. Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
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