Lecture 12 - Lecture 12 Different kinds of inhibition,...

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Lecture 12 Different kinds of inhibition, single enzyme with single substrate. Competitive inhibition: inhibitor goes into same place as substrate, when infinitely high substrate concentration. Infinity = concentration that is 100 times greater than Km. it is important to remember that bc they go to the same place, the extent of inhibition, is function of substrate concentration . The more substrate you have the less inhibition. It is true as you add more competitive inhibitor, the slope of lineweaver burk increases . The x intercept decreases ( actual Km is increased and Vmax unaffected). Non competitive- problem with catalysis, pure non competitive inhibitor binds to site that’s other then substrate site. The effect is the function of affinity of enzyme for this inhibitor, independent of substrate concentration. Low substrate concentration same percentage inhibition of the reaction velocity, not the same velocity, One can calculate Ki for noncompetitive inhibitor by measuring the velocities as function of inhibitor concentration. Observe that uninhibited velocity is twice as fast as inhibited velocity, we know that concentration is equal to Ki ---only noncompetitive inhibitor. Because finite substrate concentration gives vmax. One can observe the increasing values of 1/vmax or decreasing vmax in presence of noncompetitive. Binding is not affected—km is not affected. Inhibitor that looks like one of the substrate is competitive to one and non competitive to another. In obligate order, enzyme goes conformational change when 1 st substrate is bound, creating 2 nd binding site. The analogue for the 1 st is the competitive for the first. If producing the conformational change— there is no product. For second substrate this is non competitive inhibitor. If inhibitor that looks like none of the substrate, it is noncompetitive for both of them.
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Lecture 12 - Lecture 12 Different kinds of inhibition,...

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