SSmicmen
Michaelis-Menten Model
Description
Fits a Michaelis-Menten model to the data. This is a selfStart function.
Usage
SSmicmen(input, Vm, K)
Arguments
| input |
a numeric vector of values at which to evaluate the model. Usually, this
represents the concentration of a reactant, and the response represents the
velocity of the reaction at those substrate concentrations.
|
| Vm |
a numeric parameter representing the maximum value of the response.
|
| K |
a numeric parameter representing the input value at which half the maximum
response is attained. In the field of enzyme kinetics, this parameter is called the
Michaelis parameter.
|
Details
Because this is a selfStart function, it has an attribute called "initial", which
is a function that nls can call to compute reasonable starting values for fitting a
Michaelis-Menten model to data.
Value
returns a numeric vector of the same length as input.
It is the value of the expression Vm*input/(K+input).
If both of the arguments Vm and K are names of objects, the
gradient matrix with respect to these names is attached as an attribute named gradient.
Note
This is primarily intended for use in formulae given to nls function or similar functions.
See Also
Examples
SSmicmen(1:6, Vm=17, K=5)
with(list(Vmax=17, KM=5), SSmicmen(1:6, Vmax, KM))
tDat <- data.frame(
conc = c(0.5, 1, 2, 3, 4),
rate = c(0.2, 2.0, 2.5, 2.8, 3.0))
nls(rate ~ SSmicmen(conc, Vmax, KM), data=tDat)