While checking the effect of inhibitors on protease enzyme it was found that iodoacetate instead of inhibiting the protease activity it has enhanced the protease activity. I searched alot but could't find the possible reason for this. Can anyone explain what could be the possible reason for the same. Thank you.
Yes it can as it can alter or stabilizes the active site residues (probably SNH). Once active site residues of protease stabilizes definitely prtease activity could enhance.
If you are working with a cysteine protease, then I think it is very unlikely that the activity would be stimulated by iodoacetate, rather than inhibited, since the reagent reacts with the active site Cys residue.
If you are working with a protease from another class, then it it possible that acetylating a noncatalytic Cys residue could enhance the activity of the enzyme towards certain substrates. For example, the acetylated enzyme might have greater affinity for certain substrates. You should measure the kinetic constants Km and kcat of the untreated and acetylated enzymes to see which has been affected.
I have surely previously observed similar observation in human serum biotinidase with Hg ions (please see file; Thiol-type BIN). Hg ions have inhibited purified biotinidase at μM concentration but interestingly have activated at nM concentration. This phenomenon may be related to conformational change including glycochain structure and/or to homodimer-monomer change (please see file; The Fascio effect).
I would like to thank both the professor for your kind reply in this regard.
Yes it can as it can alter or stabilizes the active site residues (probably SNH). Once active site residues of protease stabilizes definitely prtease activity could enhance.
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