Chemical reactions physical change contrasted with

On the whole, since the main biological function of enzymes is the catalysis of net chemical changes, steady-state kinetics must be more relevant to a consideration of enzyme function (as opposed to mechanism) than the kinetics of the transient state. The requirement for only very small amounts of enzyme in order to obtain useful information also provides a major practical argument in favour of the steady-state approach. However, in the context of mechanistic studies, conclusions drawn from steady-state studies are inferred or rejected because they are or are not compatible with the mathematical behaviour of the system. Rapid reaction studies, by contrast, involve less guesswork because the postulated coihplex can often be directly observed by virtue of distinctive physical properties (e.g. absorbance or fluorescence). 

I had a similar experience in 1954 when I spoke, probably for the first time, about the possibility of oscillating reactions. At that time, I had published a short paper with Radu Balescu on the possibility that far from equilibrium we could have chemical oscillations, in contrast with what happens near equilibrium. This work was connected with involvment in the so-called "universal evolution criterion", derived with Paul Glansdorff. My lecture of 1954 had no more success than the one of 1946. The chemists were very skeptical about the possibility of chemical oscillations and in addition, said an outstanding chemist, even if it would be possible, what should be the interest The interest of chemical kinetics was at that time the discovery of well-defined mechanisms, and specially of potential energy surfaces, which one could then connect with quantum mechanical calculations. The appearance of chemical oscillations or other exotic phenomena seemed to him to be of no interest in the direction in which chemical kinetics was traditionally engaged. All this has changed, but to some extent the situation of chemistry in respect to physics remains under the shadow of this distrust of time. 

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