Initial reaction rate

During the course of an enzymatic reaction, substrate concentration decreases, and product concentration increases. This results in an overall decrease in the reaction rate, as illustrated in Figure 1. To measure the reaction rate of an enzymatic reaction corresponding to a specific substrate concentration, it is, therefore, necessary to measure the reaction rate at the beginning of the reaction. At the beginning of the reaction, the substrate concentration can be assumed to be constant, and the progress curve is close to linear. Thus, the rate of the reaction, which is equal to the slope of the progress curve, can be obtained using linear regression. The reaction rate at the beginning of the reaction is called the initial reaction rate or V0 [1]. This results in an overall decrease in the reaction rate, as illustrated in Figure 1. To measure the reaction rate of an enzymatic reaction corresponding to a specific substrate concentration, it is, therefore, necessary to measure the reaction rate at the beginning of the reaction. At the beginning of the reaction, the substrate concentration can be assumed to be constant, and the progress curve is close to linear. Thus, the reaction rate, which is equal to the slope of the progress curve, can be obtained using linear regression. The reaction rate at the beginning of the reaction is called the initial reaction rate or V 0.

The graph has time on the x-axis and the formation of product on the y-axis. The curve reflects the change in product concentration over time. The concentration of the product increases linearly over time. This shows the initial reaction rate is constant. The concentration of the product eventually plateaus as the reaction rate decreases.

Figure 1: Progress curve of a general enzymatic reaction.

References

  1. Atkins, Peter W.; de Paula, Julio; Friedman, Ronald (2009). Quanta, Matter, and Change: A molecular approach to physical chemistry. Oxford University Press. ISBN 978-0-19-920606-3.

  2. Lehninger, Albert L.; Nelson, David L.; Cox, Michael M. (2008). Principles of Biochemistry (5th ed.). New York, NY: W.H. Freeman and Company. ISBN 978-0-7167-7108-1.