Dear Sajid, one first problem in your study is how-to adress if the deltaH mesured is caused by the ligand interaction, or by the modification of dimer-monomer equilibrium. You have to well caracterise your system dimer-monomer. One other problem is about the accessibility of the interaction site. If it's different between monomer and dimer, you have to know the ratio between these two state, to managed the proportion of "active" protein.
Is it possible to separate the dimer from monomer ? Is this equilibrium concentration dependant ? In this case, you can try to execute your ITC experiment in low protein concentration. Or try to find condition in wich you can assume that you have large majority of dimer in your sample. To my mind it's difficult to start without more information. You can also try to titrate the protein with itself. If dimer/monomer is concentration dependent, you can try to titrate protein with itself. This can give you some information about the thermodynamics of the dimer/monomer formation. Hope to help. Nicolas ________________________________________ De : CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] de la part de sajid akthar [b_sajid_...@yahoo.co.in] Envoyé : vendredi 18 juillet 2014 11:24 À : CCP4BB@JISCMAIL.AC.UK Objet : [ccp4bb] ITC with heterogeneous protein Dear All, This is an off-topic question. I have protein solution of heterogeneous (contains both monomer and dimer). I want to perform ITC with this protein. I doubt whether this heterogeneity will interfere the binding study. Any advice please. Thank you Sajid
