Enzyme kinetics z Study of the rates of enzyme-catalyzed reactions z Provides information on enzyme specificities and mechanisms
Enzyme kinetics z Study of the rates of enzyme-catalyzed reactions z Provides information on enzyme specificities and mechanisms
Formula for a simple enzyme-catalyzed reaction z E = free enzyme z S = substrate z ES = enzyme-substrate complex z P = product E + S ES E + P k 1 k-1 k2
Formula for a simple enzyme-catalyzed reaction z E = free enzyme z S = substrate z ES = enzyme-substrate complex z P = product E + S ES E + P k 1 k-1 k2
What are we measuring? Increasing [S]
What are we measuring? Increasing [S]
Initial velocity z Measured at the very beginning of a reaction when very little P has been made
Initial velocity z Measured at the very beginning of a reaction when very little P has been made
For enzyme-catalyzed reactions z k 1 is rate constant for formation of ES z k-1 is rate constant for conversion of ES to E+S z k2 is rate constant for product formation. For this reaction, k2= kcat z Initial velocity assumption: measure activity before appreciable P accumulates: v0 = k2 [ES ] E + S ES E + P k k 1 2 k-1
For enzyme-catalyzed reactions z k 1 is rate constant for formation of ES z k-1 is rate constant for conversion of ES to E+S z k2 is rate constant for product formation. For this reaction, k2= kcat z Initial velocity assumption: measure activity before appreciable P accumulates: v0 = k2 [ES ] E + S ES E + P k k 1 2 k-1