enzyme kinetics Flashcards
How can an enzyme’s kinetics be studied?
Absorbance, Fluorescence, High performance liquid chromatography, Mass Spectrometry
What causes a plateau in an enzyme-substrate reaction?
Enzyme inhibition, Reverse reaction, Depletion of substrate
What are the units for rate of reaction?
µmol/min
what are the units for specific activity of an enzyme?
µmol/min/mg protein
what is the best way to describe why enzymes have a maximum velocity?
Enzymes contain a limited number of binding sites for the substrates
What is the relationship between V and [S] at low substrate concentration? (fixed enzyme conc)
They are linearly proportional
What is the relationship between V and [S] at high substrate concentration (fixed enzyme conc)
V is independent of [S]
What assumptions are made in the michaelis-menton equation?
1) enzyme binds to the substrate
2) enzyme and substrate form a complex
3) Substrate is converted to product
4) product does not revert to substrate
5) the reaction is in a steady state condition
What is assumed when defining substrate concentration [S]?
That [ES] is much smaller than [S]
When does maximum velocity of a reaction (Vmax) occur?
when all active sites of an enzyme are saturated (this occurs when [S] is much greater than Km)
How can the slowest step in an enzymatic pathway be identified?
determine the Vmax of each step
what are the units of Vmax?
µmol/min
what does km respresent?
Michaelis constant, represents the substrate concentration that gives 50% of the maximum velocity
What is the turnover number?
the number of substrate molecules converted to product per enzyme molecule in unit time when the enzyme is saturated
How can you calculate the turnover number (Kcat)?
using the equation Kcat= Vmax/[Et]
