Dear Monika, If your protein-ligand interaction is at millimolar, you need to increase injection volume in order to see heat change. Also, you can do the experiment at low temperature such as 10 degree Celsius. You can follow this paper where I have crystallized weak binding ligand and complemented with ITC. https://pubmed.ncbi.nlm.nih.gov/24957055-structure-interactions-and-evolutionary-implications-of-a-domain-swapped-lectin-dimer-from-mycobacterium-smegmatis/?from_term=Dhabaleswar+Patra&from_pos=7 Structure, Interactions and Evolutionary Implications of a Domain-Swapped Lectin Dimer From Mycobacterium Smegmatis - PubMed<https://pubmed.ncbi.nlm.nih.gov/24957055-structure-interactions-and-evolutionary-implications-of-a-domain-swapped-lectin-dimer-from-mycobacterium-smegmatis/?from_term=Dhabaleswar+Patra&from_pos=7> Crystal structure determination of the lectin domain of MSMEG_3662 from Mycobacterium smegmatis and its complexes with mannose and methyl-α-mannose, the first effort of its kind on a mycobacterial lectin, reveals a structure very similar to β-prism II fold lectins from plant sources, but with extens … pubmed.ncbi.nlm.nih.gov Hope this help.
Regards, Dhabaleswar Patra Purdue University, IN ________________________________ From: CCP4 bulletin board <[email protected]> on behalf of vipul panchal <[email protected]> Sent: Saturday, February 22, 2020 4:25 AM To: [email protected] <[email protected]> Subject: Re: [ccp4bb] Contradictory result between ITC and cocrystal structure Hi Monika, If the protein cocrystalize with ligand doesn't mean it interacts with protein. You have provided insufficient information here. Does the ligand is bound to mutant protein with atleast 2 or 3 hydrogen bonds (how many residues are mutated?) ? If no that means, it is just cocrystalizing but not interacting with mutant protein. Another possibility is, during cocrystalization ligand concentration is very high so as to force the interaction which otherwise is not possible as you observed with ITC. In other terms, affinity is too low to be detected by ITC. Cheers, Vipul On Sat, 22 Feb, 2020, 12:01 PM monika chandravanshi, <[email protected]<mailto:[email protected]>> wrote: Dear All, I have a situation, where a mutant protein does not exhibit any heat change upon titration with cognate ligand in the ITC experiment. However, it co-crystallizes with the respective cognate ligand. Also, the cocrystal structure reveals the conservation of the hydrogen bonding networks except for the mutated residues. I would like to know the possible reason for the no heat change in the ITC experiment. Looking forward to hearing from you. -- ----- With Kind Regards Monika Chandravanshi PhD Scholar, Department of Biosciences and Bioengineering Indian Institute of Technology Guwahati, Guwahati India ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
