Enzyme Kinetics: Understanding Enzyme Reactions and Comparing Enzymes - Prof. Paul J. Layb, Study notes of School management&administration

Download Enzyme Kinetics: Understanding Enzyme Reactions and Comparing Enzymes - Prof. Paul J. Layb and more Study notes School management&administration in PDF only on Docsity! 7 September Enzymes affect the kinetics of a reaction Can use enzyme kinetics to Compare chemical reactions Compare enzymes as catalysts Specificity and efficiency Study enzyme mechanisms Chemical Kinetics Experiments Rate or velocity: v = Δ [P] t S k−1 ← k 1 → P; at v0 only k1 is significant, v0 = k1 [S] Compare rates or velocities (v0) as it varies with [S] “Simple” case E + S ↔ES ↔ EP ↔ E + P E + S associate E catalyzes conversion of S to P E + P dissociate Michaelis and Menton Used initial velocities (v0), plot vs. [S] Simplifies reaction to E + S k−1 ← k 1 → ES k 2 → E + P Gives hyperbolic curve Michaelis – Menton equation V0 = Vmax [S ] KM+[S ] KM – Michaelis Constant – [S] at ½ Vmax Briggs and Haldane Applied M&M Kinetics in terms and conditions useful for enzyme comparison [ES] in “steady state” Not changing K2 rate limiting (k2< < k-1) [S] very high Enzyme is saturated [ES] ≈ [Et] [Et] known V0 = k2 [ES] So v0 = k2 [Et] Produces Terms Useful for Comparing Enzymes E + S k−1 ← k 1 → ES k 2 → E + P Turnover Number V0 = Vmax = k2 [Et] K2 = Vmax [Et ] = kcat in rxns s (measures efficiency) Michaelis Constant KM = (k−1+k2) k1