lecture 11 Flashcards
what does a progress curve measure
measures the appearance of product ( or disappearance of substrate) with time
what is the shape of the graph when there is excess substrate and why
it is linear as the amount of E is increased, the rate of reaction increases
what is the shape of the graph where there is fixed enzyme and we increase S and why
a rectangular hyperbola, as we increase S the active sites become full the reaction rate tapers off
what is Vo
the initial rate of the enzymatic reaction
what does Vo depend on so what order is it
first order kinetics as it depends on [S]
what is Vmax when does it occur
the maximum reaction velocity of an enzyme, it occurs when the enzyme conc is saturated
what is Km, what does it measyre
the substrate conc at which V= Vmax / 2, its a measure as the affinity for the enzyme to a particular substrate.
Km can also be called what
the michaelis constant
whats the michaelis-mentin equation
V = (Vm x [S])/(Km + [S])
what does a low Km value mean
An enzyme with low Km reaches half max velocity at a low amount of substrate. Low Km means the enzyme is efficient at getting substrate and reacting.
what assumptions is the michaelis menten equation based on
1: a product is not converted back to substrate
2:Haeldanes steady state assumption, the rate of ES formation = the rate of ES breakdown
3:by measuring initial rate, we assume [S] does not change over time.
what is the lineweaver-burk plot and whys it used
its a plot of 1/V vs 1/S. it is used because the hyperbolic V vs S can be difficult to determine Vmax. but lineweaver burk gives a linear graph
whats the equation for Km
Km = ( (k-1) -1 )/ (k1)
why is Km important
it characterises the interactio between one enzyme substrate pair, if an enzyme can bind many substrate there will be different Km values.
Km is [S] needed to reach half Vmax
units for Km
they are concentration units
