Not a feature of competitive inhibition?
Ans. a (Inhibitor and substrate can bind simultaneously to same enzyme molecule) (Ref. Harper 27th/Ch. 8)In noncompetitive inhibition, binding of the inhibitor does not affect binding of substrate. Formation of both El and EIS complexes is therefore possible. However, while the enzyme-inhibitor complex can still bind substrate, its efficiency at transforming substrate to product, reflected by Vmax, is decreased. Noncompetitive inhibitors bind enzymes at sites distinct from the substrate-binding site and generally bear little or no structural resemblance to the substrate.The effects of competitive inhibitors, which typically resemble substrates, are overcome by raising the con- centration of the substrate. Noncompetitive inhibitors lower Vmax but do not affect Km. Competitive Inhibitor reversibleCompetitive Inhibitors, irreversible Noncompetitive inhibitorsResemble substrateYesYesNoOvercome by | YesNoNoBind active siteYesYesNoEffect on VmaxUnchanged||Effect on Km|UnchangedUnchangedPharmacodynamics| potency| efficacy| efficacy# The lower the Km, the higher the affinity.Competitive inhibition# Vmax constant and Km increases with increasing inhibitor concentration.# Competitive inhibitors are analogues to the substrate chemically.# They bind at active site of enzyme and compete with substrate.# It is reversible; high substrate concentration can overcome it.HINT: Competitive inhibitors cross each other competitively, while noncompetitive inhibitors do not.
Inhibitor and substrate can bind simultaneously to same enzyme molecule
Inhibitor is structural analogue of substrate
Km increases
Vmax unaffected
Enzymes