Confused about Ki??

[77deuce]

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Competitive inhibitors bind in the active site of an enzyme. Uncompetitive inhibitors bind to an allosteric site on the enzyme-substrate complex.

What kind of inhibitor binds to the substrate??
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[Doogie.Howser]

All enzymes bind substrate.. What's your question?

 

[77deuce]

All enzymes bind substrate.. What's your question?

Sorry, what kind of INHIBITOR binds to the substrate 😀

 

[Doogie.Howser]

Ah- sorry! In terms of enzyme kinetics, anything that affects the substrate doesn't effect the boundaries of the enzyme. The only time the kinetics is changed is when there's a change in Vmax or Km for the enzyme. Altering the substrate doesn't create a change in the Vmax or Km of the enzyme because the enzyme itself is not altered in any way.
Does that make sense? In other words, it's a different discussion.

 

[77deuce]

Ah- sorry! In terms of enzyme kinetics, anything that affects the substrate doesn't effect the boundaries of the enzyme. The only time the kinetics is changed is when there's a change in Vmax or Km for the enzyme. Altering the substrate doesn't create a change in the Vmax or Km of the enzyme because the enzyme itself is not altered in any way.
Does that make sense? In other words, it's a different discussion.

Thanks! Well I've been looking around online to better understand Ki. What I take away from the below picture (which was written by a PhD) is that a lower Ki means a stronger inhibitor. I hope I'm not mistaken.

 

[aldol16]

Thanks! Well I've been looking around online to better understand Ki. What I take away from the below picture (which was written by a PhD) is that a lower Ki means a stronger inhibitor. I hope I'm not mistaken.

Inhibitors bind the enzyme in a way similar to the substrate but results in killing the enzyme. Many inhibitors will bind in the same mode as a substrate but contain a non-reactive moiety in place of the reactive one in the substrate. An example is HIV protease inhibitors. Inhibitors do not bind substrate - they bind to the enzyme because they're inhibiting the enzyme.

 

[77deuce]

Inhibitors bind the enzyme in a way similar to the substrate but results in killing the enzyme. Many inhibitors will bind in the same mode as a substrate but contain a non-reactive moiety in place of the reactive one in the substrate. An example is HIV protease inhibitors. Inhibitors do not bind substrate - they bind to the enzyme because they're inhibiting the enzyme.

Thanks! Now could you take it a step further and tie this info into how that all relates to the below picture? Does higher Ki mean mean a stronger or weaker inhibitor?

Any intuition on Ki would be appreciated.