This program fits initial rate data for enzyme catalyzed reactions to the equation below using the method of Wilkinson, G.N. (1961) Biochem. J. 80, 324-332.
v(obs)=Vm.So/(So+Km)
Data can be inputted and fitted as initial rates. Fitted values of Vm, Km and Vm/Km are outputted. If the enzyme concentration is known it can be inputted and values of kcat and kcat/Km calculated.
Data can also be inputted in the form of Abs/min and if the molar extinction is inputted then the Abs/min will be converted to d[P]/dt=v(obs) in M/min. Data can then be converted to M/sec and fitted. Initial rates are often very small numbers and so to ensure numerical accuracy you can multiply your data by the scaling factor of your choice before fitting the data.
Or the initial rates can be divided by the enzyme concentration to give kcat(obs) which can then be fitted.
When fitting without estimates, a linear Lineweaver-Burk plot is used to make the initial estimate of kcat and Km.