What is Enzymes? Enzyme nomenclature And Classification.

Enzymes are biological molecules that catalyze, or speed up, chemical reactions in living organisms. They are highly specific, meaning each enzyme typically catalyzes one particular chemical reaction. Enzymes are essential for life as they enable biochemical reactions to occur at rates that are necessary for the maintenance of life processes.

Enzymes are proteins that are made up of long chains of amino acids. These amino acids are arranged in a specific sequence, giving the enzyme its unique shape. The shape of an enzyme allows it to interact specifically with the molecule, called the substrate, that it is designed to catalyze.

When an enzyme binds to its substrate, it forms an enzyme-substrate complex. The enzyme then catalyzes the chemical reaction, converting the substrate into a product. Enzymes are highly efficient catalysts, often able to catalyze reactions at rates millions of times faster than the same reaction would occur in the absence of an enzyme.

Enzymes are essential for many biological processes, including digestion, metabolism, and cellular signaling. They are also used extensively in industry and medicine, for example, in the production of drugs and in the diagnosis of diseases.

Coenzymes:

Coenzymes are non-protein organic molecules that are required for the activity of certain enzymes. They are often small molecules derived from vitamins, such as NAD+, FAD, and coenzyme Q. Coenzymes often function by carrying chemical groups or electrons between enzymes and are often reused many times. Without coenzymes, some enzymes would be inactive.

Apoenzyme:

An apoenzyme is the protein portion of an enzyme, which by itself is inactive. It requires a cofactor, such as a metal ion or coenzyme, to become active. The apoenzyme and its cofactor together form the complete enzyme, called the holoenzyme.

Holoenzyme:

The holoenzyme is the complete, active form of an enzyme, formed by the combination of an apoenzyme and its cofactor. The cofactor can be a metal ion or a non-protein organic molecule, such as a coenzyme. The holoenzyme is required for the enzyme to carry out its biological function.

Properties of Enzymes:

Enzymes are biological catalysts that speed up chemical reactions in living cells. Some of the properties of enzymes include:

Specificity: Enzymes are specific to a particular substrate, and will only catalyze the reaction of that substrate.

Efficiency: Enzymes are highly efficient, with reaction rates that can be millions of times faster than the same reaction in the absence of an enzyme.

pH and temperature dependence: Enzyme activity is highly dependent on pH and temperature. Each enzyme has an optimum pH and temperature range in which it functions best.

Enzyme inhibition: Enzyme activity can be inhibited by various factors, such as substrate analogs or inhibitors that bind to the active site of the enzyme.

Regulation: Enzyme activity can be regulated by various mechanisms, such as feedback inhibition or the control of gene expression.

Reusability: Enzymes are generally reusable, as they are not consumed during the chemical reaction that they catalyze. This allows enzymes to be used repeatedly, which makes them an important tool in industrial and research settings.

The active site of an enzyme is a specific region of the protein where substrates (reactant molecules) bind and undergo a chemical reaction. This region has a unique shape and chemical composition that allows it to interact with the substrate and catalyze the reaction. The active site is typically located within a cleft or pocket on the surface of the enzyme molecule.

The specificity of the active site is critical for enzyme function, as it determines which substrates can bind and react with the enzyme. The binding process typically involves a series of weak, non-covalent interactions between the substrate and amino acid residues in the active site. These interactions include hydrogen bonds, electrostatic interactions, and van der Waals forces.

Once the substrate is bound to the active site, the enzyme can catalyze the chemical reaction by lowering the activation energy required for the reaction to proceed. This is accomplished through a variety of mechanisms, including bringing reactive groups into close proximity, stabilizing transition states, and altering the electronic properties of the substrate.

Overall, the active site of an enzyme is a highly specialized region that is essential for its catalytic activity.

 

Enzyme nomenclature:

Enzyme nomenclature is the system used to name and classify enzymes based on their chemical properties and biological functions. The Enzyme Commission (EC) is the organization responsible for the classification and nomenclature of enzymes.

The systematic name of an enzyme is based on the type of reaction it catalyzes, followed by the name of the substrate or group involved in the reaction. For example, the systematic name for the enzyme that catalyzes the hydrolysis of sucrose is "sucrose alpha-D-glucohydrolase."

In addition to their systematic names, enzymes are also commonly referred to by their common or trivial names, which often reflect the source of the enzyme or the reaction it catalyzes. For example, the enzyme lactase is commonly used to refer to the enzyme that catalyzes the hydrolysis of lactose.

Enzymes are also identified by their EC number, which is a numerical classification system based on the type of reaction catalyzed by the enzyme. The EC number consists of four numbers separated by periods, with each number indicating a different level of classification. The first number indicates the enzyme class, the second number indicates the enzyme subclass, the third number indicates the type of reaction catalyzed, and the fourth number indicates the specific enzyme. For example, lactase has the EC number 3.2.1.108, indicating that it is a hydrolase that catalyzes the hydrolysis of a glycosidic bond in lactose.

 

Classifications of enzymes:

Enzymes are based on the classification proposed by the Enzyme Commission (EC), which is an organization responsible for the classification and nomenclature of enzymes. The six classes are:

 

Oxidoreductases: These enzymes catalyze the transfer of electrons between molecules, which results in the oxidation or reduction of one or more substrates.

Transferases: These enzymes catalyze the transfer of a functional group, such as a phosphate or methyl group, from one molecule to another.

Hydrolases: These enzymes catalyze the cleavage of a bond by adding water, which results in the breakdown of larger molecules into smaller ones.

Lyases: These enzymes catalyze the cleavage of a bond without the addition of water, which results in the formation of a new double bond, a new ring structure, or the addition of a group to a double bond.

Isomerases: These enzymes catalyze the rearrangement of atoms within a molecule, resulting in the formation of an isomer.

Ligases: These enzymes catalyze the joining of two molecules, often coupled with the hydrolysis of ATP.

 

Each class is further divided into subclasses based on the type of reaction catalyzed, the substrate acted upon, and other factors. The EC classification system is widely used in biochemistry and provides a standardized way of describing enzymes

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