Welcome!

We provide some ready-made examples to demonstrate ENZO capabilities. After you open an example project, take a look at the reaction scheme and the parameters. You do not have to change anything.

When you are ready press "Start". Follow the accordance between theoretical and experimental curves. Current parameters are shown for each iteration.

Of course, you can try changing the parameters and see how the evaluation progress changes.

Example1: Active site concentration and enzyme activity correlation

We titrated the active site of Torpedo californica acetylcholinesterase (TcAChE) using m-(N,N,N-trimethylammonio) trifluoroacetophenone (NAF), a transition state analogue with affinities reported to be in the atomolar range. The reaction between the TcAChE and NAF is theoretically reversible, but due to the high NAF affinity for the active site, it can be regarded as essentially irreversible, and written as the following reaction scheme:

where E is enzyme, I the inhibitor and EI the complex. k0 is a second order association rate constant. The time course of residual enzyme activity is proportional to the active site concentration.

Example2: Autoactivation of Procathepsin B

Reaction scheme for autoactivation with product inhibition:

E stands for free active enzyme, S for enzyme precursor. k0 is second order association rate constant, while k1 and k2 are first order dissociation rate constant.

Example3: Cholinesterase reaction with butyrylthiocholine

Due to specific structural properties, such as a buried active site, a peripheral substrate binding site and a backdoor channel, cholinesterases are highly efficient and specific, but in general, they do not obey hyperbolic Michaelis-Menten kinetics in their reactions with substrates. The active site in cholinesterases is relatively large and a second substrate molecule can bind to the peripheral site at different times before the turnover of the first substrate is completed at the catalytic site. All this information can be easily drawn as a comprehensive reaction scheme:

The time course of product formation in the butyrylthiocholine hydrolysis by horse butyrylcholinesterase was measured at 14 different initial substrate concentrations, from 2 μmol to 50 mM.