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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screen-shot-2017-08-04-at-1-37-35-pm-png.222170

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Doogie.Howser

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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.
 
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77deuce

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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.
Screen Shot 2017-08-04 at 6.16.31 PM.png
 

aldol16

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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

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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.

Screen Shot 2017-08-04 at 1.37.35 PM.png
 
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