159. If an enzyme is NOT damaged during the process of entrapment in a bead, then internal pore
diffusion will:
A. Change the observed 𝑉𝑚𝑎𝑥 only
B. Change the observed 𝐾𝑚 only
C. Change both the 𝑉𝑚𝑎𝑥 and Km
D. Both the observed 𝑉𝑚 and 𝐾𝑚 will remain unchanged

Introduction to Enzyme Entrapment in Beads

Enzyme entrapment is a technique that involves confining enzymes within a solid matrix, often in the form of beads, which allows for their reuse in biochemical processes. This method is widely used in industrial applications such as biocatalysis, waste treatment, and biosensors. During entrapment, the enzyme is physically confined within the bead material, but still retains its catalytic activity, provided it is not damaged.

However, a significant challenge in enzyme entrapment is internal pore diffusion, which refers to the movement of substrate molecules into and out of the pores within the bead. This process can limit the access of substrates to the enzyme, which in turn affects the enzyme’s efficiency.

How Internal Pore Diffusion Affects Enzyme Kinetics

When enzymes are entrapped in beads, the diffusion of substrate molecules within the bead’s pores becomes an important factor. If the substrate cannot reach the enzyme efficiently due to the limitations of the pore structure, this will impact the enzyme’s reaction kinetics.

The enzyme’s activity is often described by two key parameters:

• Vmax (Maximum Velocity): The maximum rate at which the enzyme catalyzes a reaction when the substrate concentration is high enough to saturate the enzyme.

• Km (Michaelis Constant): The substrate concentration at which the enzyme operates at half its maximum velocity. It reflects the affinity of the enzyme for the substrate.

Effects of Internal Pore Diffusion

• Vmax: Internal pore diffusion can decrease the observed Vmax. This occurs because the substrate molecules are limited in their ability to diffuse into the bead’s pores, reducing the effective concentration of substrate that the enzyme can interact with. As a result, the enzyme cannot achieve its theoretical maximum catalytic rate.

• Km: The observed Km can increase as a result of reduced substrate availability inside the bead. With less substrate available inside the bead, the enzyme will appear to have a lower affinity for the substrate, as it requires higher substrate concentrations to reach half of its maximum velocity.

Therefore, both Vmax and Km will be affected by internal pore diffusion.

The Correct Answer

Given the explanations above, the correct answer to the question is:

C. Change both the Vmax and Km

This is because internal pore diffusion limits the enzyme’s access to substrate, leading to changes in both the maximum rate of the reaction (Vmax) and the apparent affinity of the enzyme for the substrate (Km).

Conclusion

Internal pore diffusion plays a crucial role in enzyme kinetics during the entrapment process. Both Vmax and Km are influenced by the ability of substrate molecules to diffuse through the bead’s pores, and understanding this can help in optimizing biocatalytic processes. If you need further clarification or details on enzyme kinetics and bead entrapment techniques.