Introduction

This comprehensive and academically structured course, belonging to the category of "Metabolic biochemistry", delves into the fascinating subject of "Enzymology". The purpose is to provide an in-depth understanding of the crucial role enzymes play in biological systems.

Defining Enzymes

An enzyme is a protein molecule that acts as a catalyst, significantly speeding up the rate of chemical reactions within a cell. They are essential for life as they regulate metabolic pathways and maintain homeostasis.

Classification of Enzymes

Enzymes can be classified based on several criteria:

Based on Catalytic Action (EC Number)

The Enzyme Commission (EC) system classifies enzymes based on their catalytic action, substrate specificity, and the manner in which they carry out their function. The EC number consists of four digits, each representing a different aspect of the enzyme's properties.

Based on Source

Enzymes can also be classified based on their source, such as animal enzymes, plant enzymes, bacterial enzymes, and fungal enzymes. This classification is often used for industrial applications, where the specific characteristics of enzymes from different sources are exploited.

Mechanism of Enzyme Action

The mechanism of enzyme action involves three steps:

Activation (Adsorption)

During activation or adsorption, the enzyme and substrate bind together, forming an enzyme-substrate complex. This binding is crucial as it brings the substrate in close proximity to the active site of the enzyme, facilitating catalysis.

Catalysis (Chemical Reaction)

In this step, the chemical reaction occurs at the active site of the enzyme. The enzyme lowers the activation energy required for the reaction, thereby increasing the rate of the reaction.

Product Release (Desorption)

After the chemical reaction has taken place and the product(s) have been formed, they are released from the enzyme-substrate complex. The enzyme is now ready to bind with another substrate molecule.

Factors Affecting Enzyme Activity

Several factors can influence enzyme activity:

Temperature and pH

Temperature and pH are two critical factors that can significantly impact enzyme activity. Optimum temperature and pH for an enzyme refer to the conditions at which it functions most effectively.

Substrate Concentration

The concentration of the substrate also affects enzyme activity. At low substrate concentrations, the rate of reaction is slow due to fewer collisions between the enzyme and substrate molecules. However, as the substrate concentration increases, the rate of reaction increases until a maximum is reached, beyond which further increases in substrate concentration have no effect on the rate of reaction.

Enzyme Inhibition

Enzymes can be inhibited either reversibly or irreversibly. Reversible inhibitors bind to the active site of the enzyme, preventing it from functioning but allowing dissociation under specific conditions. Irreversible inhibitors, on the other hand, covalently modify the active site of the enzyme, rendering it permanently inactive.

Regulation of Enzyme Activity

Enzymes are tightly regulated to ensure that their activity is maintained within optimal levels. This regulation can occur at multiple levels:

Allosteric Regulation

Allosteric regulation involves the binding of a molecule (allosteric effector) to an enzyme's allosteric site, which is separate from the active site. This binding causes a conformational change in the enzyme, affecting its activity and either enhancing or inhibiting it.

Feedback Inhibition

Feedback inhibition occurs when the end product of a metabolic pathway binds to an enzyme early in that pathway, reducing its activity and preventing further production of the product. This is a mechanism for maintaining homeostasis within the cell.

Enzymes in Industrial Applications

Enzymes are extensively used in various industrial applications due to their specificity, efficiency, and eco-friendliness. Some common uses include:

Detergents

Enzymes like proteases, amylases, and lipases are added to detergents to improve their effectiveness at breaking down stains.

Biofuels Production

Enzymes are employed in the conversion of biomass into biofuels such as ethanol and biodiesel.

Food Processing

Enzymes are used in food processing for various purposes, including tenderizing meats, ripening cheeses, producing citric acid, and brewing beer.