I would like to use the script mutate_model to evaluate different conformations of the same mutant side chain inserted in a protein. Therefore I used the script "mutate model" as suggested in the Wiki section, and repeated the procedure 5 times, expecting to obtain 5 different conformations of the mutant side chain. Instead, I obtained 5 identical proteins with side chains perfectly superimposable between each others. How can I manage myself in order to obtain 5 different models of the same mutation? Moreover, this is probably a naive question, but since repeated MD cycles generally do not produce identical results, why this protocol did not work in such a way? Many thanks and best regards
Anna Marabotti
______________________________________________ Anna Marabotti, Ph.D. Laboratorio di Bioinformatica e Biologia Computazionale Istituto di Scienze dell'Alimentazione, CNR Via Roma 52 A/C 83100 Avellino (Italy) Tel: +39 0825 299651 Fax: +39 0825 781585 Skype: annam1972 E-mail: amarabotti@isa.cnr.it Web page: http://bioinformatica.isa.cnr.it/anna.htm Funded by RNBIO: http://www.rnbio.it/ ____________________________________________________ "If you think you are too small to make a difference, try sleeping with a mosquito"
Anna Marabotti wrote: > I would like to use the script mutate_model to evaluate different > conformations of the same mutant side chain inserted in a protein. > Therefore I used the script "mutate model" as suggested in the Wiki > section, and repeated the procedure 5 times, expecting to obtain 5 > different conformations of the mutant side chain. Instead, I obtained > 5 identical proteins with side chains perfectly superimposable > between each others. How can I manage myself in order to obtain 5 > different models of the same mutation? Moreover, this is probably a > naive question, but since repeated MD cycles generally do not produce > identical results, why this protocol did not work in such a way?
If you start from the same initial conditions each time, your repeated MD cycles had better produce identical results, otherwise your science is not reproducable! Like most simulation packages, Modeller uses a pseudorandom number generator, so will yield reproducable results if the random seed is the same.
In your case, if you want to generate 5 different results from the mutate_model script, modify it to use a different random seed for each run. You can do this by changing the value of rand_seed when you create the initial environ() object.
Ben Webb, Modeller Caretaker