Dear All, I'm wondering how to calculate the free MG++ concentration in buffers which contain EDTA and MG++. Thanks very much for help, Arne -- Arne Mueller Biomolecular Modelling Laboratory Imperial Cancer Research Fund 44 Lincoln's Inn Fields London WC2A 3PX, U.K. phone : +44-(0)171 2693405 | Fax : +44-(0)171 269 3258 email : a.mueller at icrf.icnet.uk | http://www.icnet.uk/bmm/