Competitive Inhibitors and Non-Competitive Inhibitors - Essay Example

The drugs potentially target those enzymes that are responsible for the proliferation of cancer cells (Nelson, 2008).
Enzyme inhibitors diminish the enzyme's capability to combine with the substrate. They reduce the enzyme's catalytic actions. There are two kinds of inhibitors:
1. Reversible inhibitors: They are the agents or molecules that separate from the enzyme. They are competitive, that compete with the substrate to gain access to the active site of the enzyme, it lowers the KM and reduces the reaction velocity (Nelson, 2008).

A mixed inhibitor reduces the apparent substrate binding ability of the enzyme. Thus it alters the chemical nature of the active site. They are capable of binding with ES complex and thus reduce the substrate binding ability of enzymes. Mixed inhibitors can either reduce or enhance the KM or diminish Vmax (Nelson, 2008).
The non-competitive inhibitor is not influenced by E or ES. It binds with both with the same affinity. Non-competitive inhibitors decrease the Vmax while keeping the KM unchanged.
2. Irreversible inhibitors: They are the molecules or agents that do not get detached from the enzyme or from the active site of enzymes, thereby they do not allow the substrate to combine with the enzyme. Thus they bind to the enzyme tightly or permanently, inactivating the enzyme. E.g. Male baldness drug Propecia. Irreversible inhibitors are also called suicide inhibitors (Enzyme Inhibition; Nelson, 2008).

When irreversible inhibitors bind and cease the enzyme activity, it lowers the Enzyme concentration in the solution. It lowers the Vmax as less enzyme will be available to carry out the reaction. Although KM remains unaltered as it does not depend on the enzyme concentration (Enzyme Inhibition).
On enhancing the substrate the rate of reaction is increased till it reaches its maximum and then starts declining, as the substrate does not get more enzyme molecules to bind to pursue the reaction. For Competitive Inhibition Higher substrate concentration is required to procure the same velocity. If Vmax can still be reached if sufficient substrate is available, one-half Vmax requires a higher [S] than before and thus Km is larger.

Inhibitors play a major role in defining the experiment. The concentration of substrate and also the inhibitor is responsible for estimating the rate of reaction. Various drugs are being designed to inhibit the enzymes so as to prevent cell proliferation. The enzyme protease plays an imperative role in cancer cell progression. Inhibition of protease by means of drugs that can inhibit protease activity results in inhibition of tumor progression. A variety of temperature-sensitive, substrate concentration experiments has been performed to demonstrate their effect on enzyme activity (Nelson, 2008). The present scenario witness the inhibition of enzymes using drugs or toxins to find out the appropriate concentration of the drugs that should be given to suppress the enzyme (Rubin, 2003).