“The enzyme is not specific to the substrate molecule but to its transient state.” Explain this
statement.
Answers
Answer:
Explanation:
Transient-state kinetic analysis defines the elementary steps along the pathway of an enzyme-catalyzed reaction. The methods rely on rapidly mixing a substrate with a sufficient concentration of enzyme to allow a direct observation of intermediates and products formed at the active site during a single enzyme cycle. Stopped-flow methods afford observation of reactions by monitoring changes in optical signals (i.e., absorbance, fluorescence, and light scattering) as a function of time after mixing. Analysis of the substrate concentration dependence of the rates and the amplitudes of observable species can define the sequence of events that occur after substrate binding. Rapid-chemical quench-flow methods require two sequential mixing events: one to start the reaction and a second to stop the reaction by the addition of a quenching agent. One then quantifies the amount of product formed, often by chromatography, to resolve radiolabeled substrate from the product. Because one can observe the conversion of substrate to product directly on a known concentration scale, rapid quench experiments can be interpreted directly. In the final analysis, the most rigorous interpretation relies on global analysis fitting both stopped-flow and rapid quench-flow data simultaneously to establish a reaction pathway and the rates of interconversion of kinetically significant intermediates. Accordingly, transient-state kinetic methods allow a definition of a reaction sequence by direct measurement of each step to establish the kinetic and thermodynamic basis for enzyme specificity and efficiency.