Abstract
The paper presents a kinetic analysis of a reversible enzymatic reaction S⇄P involving two intermediate compounds under the condition [E]0 ≫ [S]0 + [P]0. For the case of mono-exponential behavior, we derive an equation for kobs as a function of [E]0, which emphasizes the pitfalls of oversimplifying kinetic schemes (such as the Michaelis-Menten model) for ribozyme studies. This novel apparent rate constant, which has been arrived at through mechanistic considerations, is analyzed, and the characteristic parameters obtained. The equation, which seems to fit experimental data better than conventional approximations, is used to analyze a single turnover study on an ADC1 ribozyme drawn from hepatitis delta virus RNA. The microscopic kinetic constants for such enzyme are evaluated and its mono-exponential behavior verified.
Key words: ribozyme kinetics, Michaelis-Menten, low catalytic enzyme, kinetic analysis, single turnover
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