Enzyme

An enzyme is a biological molecule, typically a protein, that acts as a catalyst to accelerate chemical reactions in living organisms. Enzymes work by lowering the activation energy needed for a reaction to proceed, which speeds up the process. They are highly specific, meaning each enzyme only works with certain substrates (the molecules they act upon) to produce a particular product.

1.0What are enzymes?

Buchner discovered and isolated the enzyme zymase from yeast cells. Kuhne coined the term enzyme. J.B. Sumner purified and crystalized urease enzyme from canavalia/Jack bean/Lobia plant. RNAase P or Ribonuclease P (a ribozyme) was discovered by Altman from a prokaryotic cell.

Enzymes, predominantly proteins with catalytic functions, are essential for various biological processes in the body. These catalysts facilitate and accelerate chemical reactions necessary for life, including metabolic processes. Enzymes interact with specific molecules, known as substrates, converting them into distinct molecules called products. This process is fundamental for sustaining life.

The initial phase of metabolism relies heavily on enzymes, which initiate and regulate these reactions. Enzyme regulation is crucial in clinical diagnostics because it directly impacts vital life processes. While most enzymes are protein-based, there are exceptions such as ribozymes. Ribozymes, derived from ribonucleic acid (RNA), are capable of catalyzing reactions involving their own bonds or other RNA molecules.

Enzymes are present in all bodily tissues and fluids. Intracellular enzymes drive the reactions in metabolic pathways, while enzymes located in the plasma membrane respond to cellular signals. Additionally, enzymes in the circulatory system play a critical role in blood clotting. Overall, enzymes are integral to the proper functioning of essential life processes, underscoring their importance in health and disease.

2.0Characteristics of Enzymes

• Almost all enzymes are proteins.There are some nucleic acids that behave like enzymes, called ribozymes.
• Enzymes are colloidal substances, which are macromolecules of amino acids and are synthesized by ribosomes under genetic control.
• Enzymes are biocatalyst (catalyzes the chemical reactions of livings)
• Enhance the rate of metabolic reaction ( chemical reaction of livings)

• Enzymes are very specific for substrate or reactions.
• They are required in very small amounts to catalyze a reaction.
• Enzymes when not in use, represent inactive form, called zymogen or pro-enzyme. Examples: Pepsinogen is an inactive form of pepsin, Trypsinogen is an inactive form of trypsin.
•  Enzymes catalysts differ from inorganic catalysts in many ways. 

• However, enzymes isolated from organisms who normally live under extremely high temperatures (eg. hot vents and sulphur springs), are stable and retain their catalytic power even at high temperature.
• Thermal stability is thus an important quality of such enzymes isolated from thermophilic organisms. e.g. Taq polymerase.

Turn over number :

• It is the number of substrate molecules converted into products per unit time by molecule of enzyme. Thus catalytic power is directly proportional to turn over number. 
• Carbonic anhydrase enzyme is considered as the fastest enzyme.

• Catalytic power of an enzyme remains the same even outside the living system.

Uncatalysed Reaction Versus Catalysed Reaction:

• In the absence of an enzyme, the Rate of reaction is only 200 molecules of H2CO3 per hour.However, in the presence of enzymes (carbonic anhydrase),the rate of reaction is 600,000 molecules every second. Therefore, the enzyme has accelerated the reaction rate by about 10 million times.

• Rate of reaction without enzyme : 200 molecules/hr.
• Rate of reaction with enzyme : 600000 molecules/sec.

3.0Enzyme Classification

Thousands of enzymes have been discovered, isolated and studied. Most Of these enzymes have been classified into different groups based on the type of reactions they catalyse. Enzymes are divided into 6 classes each with 4-13 subclasses and named accordingly by a four-digit number.

Example : Hexokinase

1. Class 2

2. Subclass 7

3. Subsub class 1

4. Reaction/Enzyme 1

1. Oxidoreductases/dehydrogenases: Enzymes which catalyse oxido-reduction between two substrates.

S-H/e^-reduced + S’ oxidized S oxidized + S’ -H/e^- reduced

2. Transferases: Enzymes catalysing a transfer of a group, G (other than hydrogen) between a pair of substrates S and S’.

3. Hydrolases: Enzymes catalysing hydrolysis of ester, ether, peptide, glycosidic, C-C, C-halide or P-N bonds.
4. Lyases: Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis leaving double bonds.

5. Isomerases: Includes all enzymes catalyzing inter-conversion of optical, geometric or positional isomers.
6. Ligases: Enzymes catalysing the linking together of 2 compounds, e.g., enzymes which catalyse joining of C-O, C-S, C-N, P-O etc. bonds.

4.0Key Enzymes in the Kidneys

The kidneys are vital organs involved in various physiological processes. They contain several important enzymes that help regulate blood pressure, metabolize drugs and toxins, and maintain electrolyte balance. Here are some key enzymes found in the kidneys:

1. Renin: It regulates blood pressure. It converts angiotensinogen (produced by the liver) into angiotensin I. This conversion is a part of the renin-angiotensin-aldosterone system (RAAS), which helps regulate blood pressure and fluid balance.
2. Angiotensin-Converting Enzyme (ACE): It converts angiotensin I to angiotensin II. Angiotensin II is a potent vasoconstrictor that raises blood pressure and stimulates aldosterone secretion. ACE is found in both the lungs and kidneys.
3. Aldose Reductase: It is involved in glucose metabolism. It converts glucose to sorbitol. This enzyme is important in conditions like diabetic nephropathy.
4. Glutaminase: It metabolizes glutamine. It helps produce ammonia, which is excreted in the urine. This process aids in the regulation of acid-base balance.
5. Adenosine Deaminase: It participates in purine metabolism. It regulates adenosine levels, which can influence kidney function and blood flow.
6. Carbonic Anhydrase: It catalyzes the conversion between carbon dioxide and bicarbonate.it is crucial for maintaining acid-base balance in the blood, especially in the proximal tubules of the kidneys.
7. Urease: It breaks down urea. It converts urea into ammonia and carbon dioxide. While less prominent in humans compared to other species, it can be involved in certain pathological conditions.

These enzymes play essential roles in maintaining homeostasis and ensuring proper kidney function, influencing various physiological processes from blood pressure regulation to the maintenance of electrolyte balance.

5.0Industrially Important Enzymes

Enzymes are vital in enhancing efficiency, reducing costs, and creating new products across various industries. Below are key enzymes and their industrial applications:

1. Proteases

• Applications: Detergents, food processing, leather manufacturing
• Examples: Subtilisin, Pepsin

2. Amylases

• Applications: Food and beverage industry, biofuel production
• Examples: Alpha-Amylase, Beta-Amylase

3. Cellulases

• Applications: Textile, paper, and biofuel industries
• Examples: Endo-Cellulase, Exo-Cellulase

4. Lipases

• Applications: Food industry, detergents, biodiesel production

5. Lactase

• Applications: Dairy industry
• Example: Beta-Galactosidase

These enzymes are integral to modern industry, helping to optimize processes, improve product quality, and drive innovation. Their specific catalytic functions make them indispensable across various sectors.

6.0Enzymes in the Human Body

Enzymes are crucial for a range of biological processes, including digestion, metabolism, cellular repair, and detoxification. Below is an overview of key enzymes and their functions:

These enzymes are vital for maintaining homeostasis and supporting the complex biochemical processes necessary for life. Each enzyme operates in a specific context to ensure proper functioning of the body.

7.0Enzyme in Papaya

Papaya contains an enzyme known as papain. Papain is an enzyme derived from the papaya fruit (Carica papaya), particularly from the latex of the unripe fruit.

Function:

1. Proteolytic Activity: Papain is a protease enzyme that breaks down proteins into smaller peptides and amino acids. 
2. Medical Uses: Digestive supplements. It is used in supplements to aid protein digestion and improve gastrointestinal health.
3. Cosmetics: Skincare Products. 
4. Pharmaceuticals: Medications and supplements, incorporated into some products to support digestion and overall gastrointestinal health.