How much can an intermediate state influence competing reactive pathways?

The issues related to competing reactive pathways and the mechanism of controlling chemical reactions were discussed. The desired product was selected while suppressing the completing channels by means of well-designed subpulses with frequencies around the reference value. The quantitative aspects of enzymatic activity were studied in which the rate at which a reaction proceeds to form the product depends on the position on the energy scale of the short-lived intermediate. The interpretations of the lock and key mechanism suggested that in the presence of the appropriate substrate the active site may change in order to suit the substrate's shape.