Dear all,
What is the best strategy to use heme and other porphyins for their titration of binding to proteins by ITC. The solvents used for porphyrins (DMSO, NaOH, DMF) are not compatible with protein integrity.
Many thanks for any suggestions in advance.
JDD
Dear Jordan,
Based on Product Information, heme (hemin) is soluble at ~ 1mg/ml (1.5 mM) in DMSO. Since proteins in general can tolerate DMSO concentrations no higher than 5%, the highest concentration of the hemin solution you would be able to use is ~ 75 microM (by diluting your stock 20-fold in protein dialysate), and using 5% DMSO in the protein solution for matching purposes. Depending on the binding affinity and enthalpy, you may decide whether the hemin solution should be used in the ITC cell or in the titration syringe.
Dear Conceicao,
many thanks for your detailed answer. It provides important clues.
Best wishes,
Jordan
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