Enzymes Session II

We know that enzymes react with substrate molecules to convert them into products. Enzyme activity refers to the ability of enzymes to catalyze or speed up chemical reactions. Did you know that temperature can significantly affects the activity of enzymes? It's fascinating how temperature affects the movement and energy of molecules, including both the enzymes and the substrates. When the temperature rises, these molecules become more energetic and move around faster. But what does that imply for enzyme activity? Well, the rise in speed results in more frequent collisions between enzymes and substrates.

More collisions give rise more chances of successful interactions and catalytic reactions. This, in turn, speeds up the overall rate of enzyme activity and the conversion of substrates into products. However, it is important to note that there is an optimal temperature range for enzyme activity. Beyond this range, extremely high temperatures can have detrimental effects on the enzyme. The optimal temperature range for most human enzymes falls within thirty five to fourty degrees Celsius.

At very high temperatures, the thermal energy can break hydrogen bonds, disulfide bridges, and other weak bonds that contribute to the stability of enzymes. As a result, the enzyme undergoes denaturation. Denaturation refers to the structural and functional changes that occur in proteins. Denatured enzyme loses its proper folding and shape. The denatured enzyme becomes non-functional. This implies it cannot effectively bind to substrates and catalyze reactions.

Another factor that effects the activity of enzymes is pH. pH is a measure of how acidic or basic a solution is. It tells us how many hydrogen ions are there in a solution. A pH value below seven indicates an acidic solution. A pH above seven indicates a basic solution. A pH of seven is considered neutral. Water has a pH value of seven.

Now, let's explain how changes in pH can affect enzyme activity. Enzymes are special proteins that help speed up chemical reactions in our bodies. They have specific shapes that allow them to bind to a type of molecules called substrates and convert them into products. Enzymes work best at a particular pH level known as their optimum pH. At this pH, the structure of enzyme is stable. Active site of enzyme is also in the correct shape to efficiently bind to the substrate and carry out the reaction.

When the pH changes from the enzyme's optimum level, it can disrupt the enzyme's structure. This disruption is mainly due to the ionic and hydrogen bonds that hold the enzyme's shape together. These bonds are sensitive to pH changes. In simpler terms, think of the enzyme as a lock and the substrate as a key. The lock has a specific shape that fits perfectly with the key. But when the pH is not optimal, it is like the lock gets distorted, and the key no longer fits well. So, the reaction doesn't happen as efficiently.

Different enzymes have different optimal pH. This is because they are found in different parts of the body or perform different functions. For example, stomach enzymes work best in the acidic environment of the stomach, helping with digestion. In contrast, enzymes in the small intestine prefer a more alkaline pH because they continue the digestion process in that environment.

Enzyme activity is also affected by the concentration of the substrate. When the concentration of the substrate is low, there are fewer substrate molecules available for the enzyme to interact with. As a result, the enzyme substrate collisions are less frequent. The reaction rate becomes relatively slow. As the substrate concentration rises, the rate of the reaction also rises. This is because more substrate molecules are available for the enzymes. This implies there is a higher likelihood of enzyme-substrate collisions.

However, there comes a point where increasing the substrate concentration further does not result in a proportional rise in the reaction rate. This is because the enzyme reaches a state of saturation. At saturation, all available active sites on the enzyme are taken up by substrate molecules. When the enzyme's active sites are saturated, additional substrate molecules cannot bind to the enzyme. Although there might be more substrates, they have to wait for active sites to become available. This limits the rate at which the enzyme can convert substrates into products.

The concentration of enzymes also effect the activity of enzymes. Generally, a rise in the concentration of enzymes results in a an rise in reaction rate. This is because more enzymes are available to bind with substrates. However, if the concentration of substrate is limited then further rises in enzyme concentration do not effect the reaction rate.

Enzyme inhibitors are molecules that bind to enzymes and interfere with their normal function. They can either enhance or reduce the activity of the enzyme. Inhibitors can be classified into two main types. These are reversible inhibitors and irreversible inhibitors. Reversible inhibitors bind to the enzyme through non covalent interactions. Reversible inhibitors are ones that can attach to the enzyme temporarily, like a magnet sticking to a metal surface. This attachment can be undone, and the enzyme can return to working normally.

Reversible inhibitors can further be classified into competitive, non competitive, and uncompetitive inhibitors. Competitive inhibitors compete with the substrate for the active site of enzyme. They bind reversibly to the active site. Competitive inhibitors block the substrate from binding. They reduce enzyme activity. Increasing substrate concentration can overcome the effects of competitive inhibition.

Non competitive inhibitors bind to a site on the enzyme other than the active site. That site is known as the allosteric site. Binding of non competitive inhibitors causes a change in shape and structure of active site of enzyme. Now substrate can not bind to active site of enzyme. As a result, enzyme activity is reduced. Non competitive inhibition is not overcome by increasing substrate concentration.

Uncompetitive inhibitors work by attaching to the enzyme only when it already has the substrate attached to it. Once the inhibitor binds, it prevents the release of the product that the enzyme would normally produce. It's like a lock that can only be closed when the key is already inside.

Irreversible inhibitors form covalent bonds with the enzyme. These inhibitors cause permanent inactivation of enzyme. These inhibitors often contain reactive functional groups. These reactive functional groups bind irreversibly to specific amino acids in the enzyme's active site.

Immobilized enzymes are enzymes that are stuck to a solid material, like tiny beads. This helps keep the enzymes in one place during chemical reactions. There are a few benefits to immobilizing enzymes. Immobilization can protect enzymes from getting damaged or destroyed, Since immobilized enzymes are attached to a solid support, they can be easily separated from the reaction mixture and reused multiple times. This saves time and money by not having to make or purify new enzymes for each reaction.