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Is it possible to do the following:

  1. Enzyme E binds to its substrate S without catalysis;
  2. Add a controllable stimulus, such as light, adding or removing chemicals;
  3. The enzymatic reaction is triggered by the stimulus.

The word controllable means I can add the stimulus at any time I want. Before I add the stimulus, the enzyme keeps binding to the substrate specifically but no reaction takes place.

This is what I mean by separating binding and catalysis in two steps.

In the case of allosteric regulation, some chemicals will inhibit the activity of an enzyme. For example, ATP will inhibit the activity of phosphofructokinase 1 (PFK1). But I'm not sure whether this allosteric inhibition also hinders PFK1's binding to the substrate, which does'nt satisfy my description above.

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  • $\begingroup$ Interesting question, but need some more specifics. This depends strongly on the enzyme, are you focusing on FPK1? Do you consider the enzyme substrates themselves as "controllable"? (That gives you more options.) Must the enzyme bind all its substrates irreversibly in the inactive state (for FPK1, ADP and fructose-6P)? Is this for detailed enzyme mechanism studies in vitro, so the molecular dynamics is important? (For simply keeping the enzyme inactive in cells this seems unnecessary.) $\endgroup$ – Roland Jan 23 '16 at 10:32
  • $\begingroup$ @Roland Thank you for your comment. I'm actually focusing on methionine aminopeptidase (MetAP). I mentioned FPK1 because it is a typical example for allostery. The substrate of MetAP is a peptide with methionine as its N termini, which could be controllable if necessary (but how?). It is prefered if the binding is irreversible, but also acceptable if reversible. The assay is designed for an in vitro biotechnology. I don't think such a method is already available for MetAP, but any similar method may be helpful for me to adapt it to MetAP. $\endgroup$ – Wei Feng Jan 23 '16 at 11:56
  • $\begingroup$ In that case you need to review the details of the reaction mechanism for MetAP. Some enzymes bind their substrates and cofactors sequentially, and if the peptide happens to bind first, you might achieve what you want by withholding a cofactor. But if peptide binding is the event that initiates reaction, this may not be possible. If the enzyme requires a posttranslational modificatin for activity (e.g. phosphorylation) that might be another possibility. $\endgroup$ – Roland Jan 23 '16 at 17:22

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