Dear all, I am going to run some MD simulation of a protein bearing a copper cluster (3 Cu2+ nominally charge 2+) coordinates to histidine residues. As far as concerning the importance of this cluster in the enzymatic activity (this would require QM/MM), my issue is how to interpret the "whole" system [HIS_{2}-Cu2+]_{3} in term of force field. From literature and from previous posts in this mailing list, in MD system similar to mine (aminoacid coordinating ions) are treated as an unique "residues" (i.e. HEME group). My first try was to perform MD without restraints on Cu2+, but unfortunately at 100K (I am doing an equilibration from 100K to 300K) after few ps one of the Cu2+ left already its position (basically it is flying away). Second try was to put restraints on the system between the Cu2+ and the N-HIS. However, my doubt is how bad is this assumption respect to the possibility to consider the whole system Cu2+-HIS as an unique residue in the topology file. I am aware that for the latest hypothesis I should reconsider all the properties (i.e. charges, angles, etc ...), so a long way and hard work. Think about that I need to put a O2 molecule inside of the Cu2+ cluster in a second study.
Any suggestion, comments and anything else are very welcome. Thanks in advance Regards andrea -- ------------------------------- Andrea Spitaleri PhD Dulbecco Telethon Institute c/o DIBIT Scientific Institute Biomolecular NMR, 1B4 Via Olgettina 58 20132 Milano (Italy) Tel: 0039-0226434348/5622/3497/4922 Fax: 0039-0226434153 http://sites.google.com/site/andreaspitaleri/ ------------------------------- ----------------------------------------------------------------- La tua mano puo' lasciare un segno importante. Dona il tuo 5 per mille al San Raffaele di Milano. E' SEMPLICE E NON COSTA NULLA. Basta indicare nell'apposito riquadro della dichiarazione dei redditi "Finanziamento della ricerca sanitaria" il codice fiscale della Fondazione Centro S. Raffaele del Monte Tabor: 03 06 42 80 153 e ricordarsi di firmare. Per saperne di piu': 5permi...@hsr.it o vai sul sito http://www.5xmille.org. _______________________________________________ gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/mailing_lists/users.php