[B_abd]

Hello!

I am new in studying enzyme kinetics and I have some difficulties in analyzing experimental data. I have an experiment of substrate metabolism in the presence and absence of an inhibitor. From the experimental data, I have concentration of substrate vs time as parameters. My question is how I can get from concentration to velocity in order to make after the Lineweaver–Burk plot and to determine Km, vm and the inhibition type. The velocity depends on the enzyme concentration? It should, but then how I calculate the velocity? Is there any formula? I know that the velocity is Δ concentration / Δ time, but I don t want to make a wrong approximation using a line instead of a curved line.

As an example, I have these experimental data:
time(min)    concentration (μM)
0                0.492978
0.5             0.425282
1                0.367152
2                0.290506
3                0.255639
4                0.195918
5                0.148944
6                0.120501
7                0.091908
8                0.072618
10              0.049013
15              0.029523
20              0.020192

If I put them on a grafic, the profile is decreasing exponentially.

Thank you for any help or any suggestion!

[Babcock_Hall]

Do you know what is meant by the expression "initial velocity" as it pertains to enzyme kinetics?

[Babcock_Hall]

Enzyme-catalyzed reactions often slow down within second or minutes after they are initiated, because the substrate falls in concentration or other reasons.  That is why one takes the rate when less than about 5-10% of the substrate has been consumed, and often one ignores the data after the initial rate.