The Study of Fast Reactions by the Stopped Flow Method

Abstract

The mechanisms involved in protein reactions may be elucidated by investigating the reaction kinetics. There are two investigative approaches in ascertaining the combination of elementary steps which constitute these mechanisms:(1) steady state kinetics permits analysis of the overall reaction in which protein substrates are converted into products without examining the protein molecule itself; and (2) transient kinetics allows the direct measurement of each component in the overall reaction. In this latter case, attention is focused on changes occurring in the molecule upon binding to another protein whereas the study of the equilibrium (steady state) reaction does not examine the protein molecule directly. Equilibrium studies have wider applicability since they usually require only a small amount of protein and do not involve the use of special equipment. Necessarily, the information obtained is indirect and often ambiguous. Although transient kinetics requires special techniques for measuring the rates of fast reactions in solutions, it provides information which is far more direct and useful for elucidating complicated mechanisms of reactions. Thus, the two approaches are complementary and both are indispensable for the study of protein reactions.