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Is it possible to calculate salt bridges in Martini?
- Rajat Desikan
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I have a fully atomistic as well as a Martini simulation of a protein in membrane. I want to calculate the number of salt bridges using standard gromacs tools (g_saltbr) and compare the numbers I get in the two simulations. Is this feasible? Are there any pitfalls that I should be aware of? The protein is highly negatively charged (-60), therefore I have 60 Na+ ions in both simulations.
Thanks
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- xavier
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Rajat Desikan wrote: Hi All,
I have a fully atomistic as well as a Martini simulation of a protein in membrane. I want to calculate the number of salt bridges using standard gromacs tools (g_saltbr) and compare the numbers I get in the two simulations. Is this feasible? Are there any pitfalls that I should be aware of? The protein is highly negatively charged (-60), therefore I have 60 Na+ ions in both simulations.
Thanks
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- Rajat Desikan
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I know how to remove the lipids from the trajectory file. But how do I remove it from the .tpr?
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- Rajat Desikan
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I have a query regarding the distance cutoff for saltbridges in Martini.
For the fully atomistic simulation, I analysed saltbridges in VMD using a distance cutoff of 3.2 ang (Between oxygen and nitrogen atoms of opposite charged AA) and got around 12 saltbridges. However, for the Martini simulation, the same distance cutoff yields zero salt bridges (no output until a cutoff of 5 ang). Is there a need for a bigger cut-off?
Thanks
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- xavier
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If not you can generate a new tpr be simply defining a system without lipids and use that new tpr.
Rajat Desikan wrote: Thanks a lot, Xavier.
I know how to remove the lipids from the trajectory file. But how do I remove it from the .tpr?
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- xavier
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The best way to choose the cutoff is to choose a salt bridge you know is present (eg. by visualisation) and plot the histogram of the distance ... the minimum after the first pic should be your cutoff.
Rajat Desikan wrote: Hi All,
I have a query regarding the distance cutoff for saltbridges in Martini.
For the fully atomistic simulation, I analysed saltbridges in VMD using a distance cutoff of 3.2 ang (Between oxygen and nitrogen atoms of opposite charged AA) and got around 12 saltbridges. However, for the Martini simulation, the same distance cutoff yields zero salt bridges (no output until a cutoff of 5 ang). Is there a need for a bigger cut-off?
Thanks
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- Rajat Desikan
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That is a wonderful piece of advice. Thanks.
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- Rajat Desikan
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- xavier
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Rajat Desikan wrote: I calculate the histogram of the distance between the residues participating in the salt bridge using g_mindist, right? Or is there a better way?
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