Dear RG experts,please help me for the prediction.
I think there is a relation between Ki & IC50 which is Cheng-Prussoff equation from this equation you can determine any one by other .
Hi, for your purpose on lineI have found this interesting tool the link is:
http://botdb.abcc.ncifcrf.gov/toxin/kiCalES.jsp;jsessionid=6BE0DFA8AFF26161E5B4C8CE1C1D5F85
sincerely
Simone
http://eprints.maynoothuniversity.ie/1847/1/Krippendorff_etalPreprint2009_MechanismBasedInhibition.pdf
link gives you some idea...
Pharmacology: Principles and Practice
By Miles Hacker, William S. Messer II, Kenneth A. Bachmann (click the link below)...
https://books.google.co.in/books?id=5YDMmjWXe-AC&pg=PA308&lpg=PA308&dq=predict+IC50+from+inhibitory+constant+%28Ki%29?&source=bl&ots=HH_BXzB-lm&sig=icL2Q-S0uI_gqpFK0e2VQQoNLd8&hl=en&sa=X&ei=poWjVOv9PMWHuATI-4DYCQ&ved=0CDAQ6AEwAw#v=onepage&q=predict%20IC50%20from%20inhibitory%20constant%20(Ki)%3F&f=false -Google book
Dear Vijey Aanandhi M.VIJEYAANANDHI Muthukumar ; I think your request gave you Dr.Umesh in his attachment file.
Good luck
In my experience, Alaa M is correct. Cheng-Prusoff established a formula for conversion of IC50 to Ki, using a Km correction (I believe. Sorry, long time ago, do not have the paper in front of me). Using this equation, I have matched multiple assay IC50s with Ki determined by other investigators (using other methods for Ki determination). However, be prepared to defend your IC50 ~ Ki conversions with this paper, or derive it yourself- I have experienced much skepticism (to use a polite term) from some enzymologists by incorporating this equation. Other enzymologists are more familiar with this paper.
Biochem Pharmacol. 1973 Dec 1;22(23):3099-108.
Relationship between the inhibition constant (K1) and the concentration of inhibitor which causes 50 per cent inhibition (I50) of an enzymatic reaction.
Cheng Y, Prusoff WH.
However, PubMed shows a more recent entries (1998, 1993, others?) for Cheng-Prusoff corrected equations. It has not been my experience that the equation needs correction, but include objective dissension as a possibility.
The inhibitory constant (Ki) and the IC50 of a drug that is known to cause inhibition of a cytochrome P450 (CYP) enzyme have to do with the concentration needed to reduce the activity of that enzyme by half. More specifically the Ki is reflective of the binding affinity and the IC50 is more reflective of the functional strength of the inhibitor for a drug. Since the Ki takes into account the IC50 is its calculation, the Ki is being reported more often by drug companies. For noncompetitive inhibition of enzymes, the Ki of a drug is essentially the same numerical value as the IC50, whereas for competitive and uncompetitive inhibition the Ki is about one-half that of the IC50's numerical value.
The smaller the Ki, the greater the binding affinity and the smaller amount of medication needed in order to inhibit the activity of that enzyme. If a Ki is much larger than the maximal drug concentrations that a patient is typically exposed to from typical dosing, then that drug is not likely to inhibit the activity of that enzyme.
http://www.ebmconsult.com/articles/inhibitory-constant-Ki-drug-interactions?from=pw
Please use the equation of Cheng and prusoff.
ki=ic50/[1+(radioligand concentration/kd)]
Biochem.pharmacol.22:3099-3108, 1973
But how do you calculate Kd and Ki when the only thing you know is IC50?
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