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Biology HLTheme C: Interaction and interdependence (HL)
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Optional kinetic-model extension, not claimed as prescribed IB HL depth: Explain the difference between reversible competitive inhibition in the standard active-site model and pure noncompetitive enzyme inhibition, referring to substrate binding and catalytic activity.
States that in the standard competitive model the inhibitor and substrate bind mutually exclusively at the active site; the inhibitor need not be a close structural copy of the substrate.
States that increasing substrate concentration can overcome competitive inhibition, since substrate and inhibitor compete for the same active site.
States that a pure noncompetitive inhibitor binds free enzyme and enzyme-substrate complex with equal affinity at a site distinct from the substrate-binding site.
Explains that it reduces catalytic capacity and Vmax without changing Km, so increasing substrate concentration cannot restore the uninhibited maximum rate; substrate binding is not necessarily prevented.
Check your reasoning:Competitive inhibition increases apparent Km while leaving Vmax unchanged; pure noncompetitive inhibition lowers Vmax without changing Km. A remote binding site alone does not distinguish pure noncompetitive from mixed inhibition.
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