The flexibility during the juxtaposition of reacting groups and the upper limits of enzyme reactions.

The combination between enzymes and substrates occur only after their reacting groups are in juxtaposition with each other. This will greatly reduce the probability of their effective encounters. However, the results calculated with the finite elements method show that the reaction limits will not decrease substantially if van der Waal's forces and a reasonable flexibility during such a juxtaposition are taken into account.