1. INTRODUCTION OF ENZYME IN MEDICINE dr. Ali

Introduction of Enzymes in Medicine

What is an Enzyme?

Enzymes are biological catalysts that speed up chemical reactions in the body. They are proteins (except for ribozymes, which are RNA-based) transcribed and translated from genetic information. Because of their catalytic nature, they are also known as biocatalysts.

Properties of Enzymes:

  • Colloidal nature in solution.

  • Sensitive to temperature and pH changes.

  • Highly specific in their function.

What is a Coenzyme?

A coenzyme is a non-protein, organic molecule that assists an enzyme in catalyzing reactions. Coenzymes are usually derived from vitamins and have low molecular weight. They are dialyzable (can pass through a semipermeable membrane).

Examples of Coenzymes:

  • NAD+ (Nicotinamide Adenine Dinucleotide) – Derived from niacin; involved in redox reactions.

  • FAD (Flavin Adenine Dinucleotide) – Derived from riboflavin; helps in energy metabolism.

  • Coenzyme A (CoA) – Important for fatty acid and carbohydrate metabolism.

  • Thiamine Pyrophosphate (TPP) – Assists in decarboxylation reactions.

  • Biotin – Carries carbon dioxide in carboxylation reactions.

How are Enzymes Classified?

Enzymes are classified by the International Union of Biochemists (IUB) into six major classes based on their function:

Class

Function

Example

Oxidoreductases

Catalyze oxidation-reduction reactions (electron transfer)

Lactate dehydrogenase (LDH)

Transferases

Transfer functional groups between molecules

Alanine transaminase (ALT)

Hydrolases

Break bonds by adding water (hydrolysis)

Amylase (digests starch)

Lyases

Add or remove groups to form/break double bonds

Fumarase (Krebs cycle)

Isomerases

Rearrange atoms within a molecule

Phosphoglucoisomerase

Ligases

Join two molecules using ATP energy

DNA ligase

Why is the Understanding of Enzymes Critical in Medicine?

Enzymes are important for diagnostics, therapy, and laboratory analysis in medicine.

1. Diagnostic Uses of Enzymes

  • Measuring or monitoring enzyme levels in clinical samples (blood plasma) to detect disease.

  • Plasma Enzymes:

    • Plasma Function-Specific Enzymes

      These are enzymes primarily produced in the liver and secreted into the plasma to carry out systemic functions like blood clotting, immunity, and lipid metabolism. Their concentrations in plasma can indicate organ function or dysfunction.

      Examples of Plasma Function-Specific Enzymes:

      1. Coagulation Factors – Help in blood clot formation (e.g., Prothrombin, Fibrinogen).

      2. Complement Factors – Aid the immune system in destroying pathogens (e.g., C3, C5-C9).

      3. Lipoprotein Lipase – Breaks down fats for energy storage and metabolism.

      4. Ceruloplasmin – Involved in copper and iron metabolism.

      5. Renin – Regulates blood pressure via the renin-angiotensin system.

      6. Cholinesterase – Breaks down neurotransmitters, essential for nerve function.

      Plasma Non-Specific Enzymes

      These enzymes are normally found in low concentrations in plasma but are released into the bloodstream when tissues are damaged. Their presence in plasma serves as a marker for disease or organ damage.

      Examples of Plasma Non-Specific Enzymes:

      1. Creatine Kinase (CK) – Found in muscle and brain; used to diagnose heart attack and muscle injury.

      2. Alkaline Phosphatase (ALP) – Found in the liver and bones; used to detect liver disease and bone disorders.

      3. Lactate Dehydrogenase (LDH) – Found in multiple tissues; a marker for tissue damage.

      4. Aspartate Aminotransferase (AST) – Found in the liver, heart, and muscles; used to diagnose liver damage and heart attacks.

      5. Alanine Transaminase (ALT) – Specific to the liver; an important marker for hepatitis and liver disease.

      6. Aldolase – Found in muscle; elevated in muscle disease.

      Why Do Plasma Non-Specific Enzymes Appear in Blood?

      • These enzymes are normally contained within cells and are released into the blood when cells are damaged due to injury, disease, or stress.

      • Their elevated presence in plasma serves as an indicator of organ damage, and they are used in diagnostic tests to identify conditions affecting the heart, liver, muscle, or bones.

      Therapeutic Uses of Enzymes

Enzymes are utilized in various therapeutic applications, offering innovative treatments for specific diseases:

  • Streptokinase/Urokinase: These enzymes are used to dissolve blood clots in patients experiencing acute myocardial infarction or pulmonary embolism, thus restoring blood flow.

  • Recombinant Tissue Plasminogen Activator (rtPA): This is used in the emergency treatment of stroke and heart attack, where rapid dissolving of clots reduces damage to tissues.

  • Papain: An enzyme derived from papaya, it has anti-inflammatory properties and is used in the treatment of conditions such as arthritis.

3. Analytical Uses of Enzymes

Enzymes are employed in laboratory tests to analyze various substances in biological samples. Their high specificity enhances the accuracy of these tests, which can include:

  • Glucose Oxidase/Peroxidase: Used to measure blood glucose levels in diabetic patients.

  • Urease: Utilized to detect urea levels in plasma, aiding in the assessment of renal function.

  • Lactate Dehydrogenase (LDH): Measured to determine tissue damage, including myocardial infarction and liver diseases.

Plasma Non-Specific Enzymes & Disease Markers

Elevated levels of certain enzymes indicate specific organ damage:

Organ

Enzyme Markers

Clinical Significance

Heart

Creatine kinase-MB (CK-MB), LDH, AST

Myocardial infarction (heart attack)

Liver

ALT, AST, ALP, GGT

Hepatitis, cirrhosis, bile obstruction

Biliary Tract

ALP, GGT, 5'-Nucleotidase

Gallstone blockage, liver disease

Muscle

CK-MM, Aldolase

Muscular dystrophy, myopathies

Pancreas

Amylase, Lipase

Acute and chronic pancreatitis

Prostate

Acid phosphatase (ACP), PSA

Prostate cancer marker

Bone

ALP isoenzymes

Bone cancer, Paget’s disease

Enzymatic Markers of Disease

Enzymatic markers are specific enzymes whose elevated levels in the bloodstream can indicate a particular type of organ damage or disease. Medical professionals use these markers to diagnose conditions, monitor disease progression, and evaluate treatment efficacy. Understanding the enzymes associated with different diseases allows for targeted and effective medical interventions. Here is a detailed overview of enzymatic markers classified by the organ system and the associated clinical significance.

1. Cardiac Disease

Enzymatic Markers:

  • Creatine Kinase-MB (CK-MB):

    • Function: CK-MB is an isoenzyme found primarily in heart muscle.

    • Clinical Significance:

      • Appears in the serum within 3 hours post-myocardial infarction (heart attack) and peaks at 24 hours.

      • It then gradually declines, making it useful for diagnosing acute heart issues and determining the time window of an infarction.

  • Lactate Dehydrogenase (LDH):

    • Function: LDH is involved in the conversion of lactate to pyruvate during anaerobic respiration.

    • Clinical Significance:

      • Peaks later after a heart attack and can remain elevated for a longer period.

      • Useful for detecting myocardial infarction when CK-MB results are inconclusive.

  • Aspartate Aminotransferase (AST):

    • Function: AST is an enzyme that helps with amino acid metabolism and is found in heart and liver tissues.

    • Clinical Significance:

      • Elevated AST levels can suggest myocardial infarction and also indicate liver damage, requiring further testing to differentiate between the two.

2. Liver Disease

Enzymatic Markers:

  • Alanine Aminotransferase (ALT):

    • Function: ALT is primarily found in the liver and plays a role in amino acid metabolism.

    • Clinical Significance:

      • Increased levels are specific to liver damage, as ALT is released into the bloodstream when liver cells are injured.

      • It is a key marker in diagnosing hepatitis, cirrhosis, and fatty liver disease.

  • Aspartate Aminotransferase (AST):

    • Clinical Significance:

      • Elevated AST levels alongside ALT can indicate hepatocellular injury.

      • An AST/ALT ratio greater than 2 is often associated with alcoholic liver disease.

  • Alkaline Phosphatase (ALP):

    • Function: ALP is involved in breaking down proteins and is found in liver, bile ducts, and bones.

    • Clinical Significance:

      • Elevated levels can indicate cholestasis (bile obstruction) or liver diseases such as primary biliary cirrhosis.

  • Gamma-Glutamyl Transferase (GGT):

    • Function: GGT is involved in the metabolism of glutathione and is a marker for liver health.

    • Clinical Significance:

      • High levels typically indicate liver dysfunction and are used to confirm other liver enzyme elevations.

3. Pancreatic Disease

Enzymatic Markers:

  • Amylase:

    • Function: Amylase breaks down carbohydrates.

    • Clinical Significance:

      • Levels can increase significantly (up to 1000 times) in cases of acute pancreatitis.

      • However, this enzyme is not specific to the pancreas and can also be elevated in other conditions.

  • Lipase:

    • Function: Lipase is responsible for fat digestion.

    • Clinical Significance:

      • More pancreas-specific than amylase, elevated lipase levels are a strong indicator of acute pancreatitis.

      • It usually remains elevated longer than amylase, providing additional diagnostic information.

4. Muscle Disease

Enzymatic Markers:

  • Creatine Kinase (CK):

    • Function: CK is an enzyme that helps produce energy in muscle cells.

    • Clinical Significance:

      • Elevated levels can indicate muscle damage or disorders such as muscular dystrophy or rhabdomyolysis.

      • Different isoenzymes (CK-MM for muscle, CK-BB for brain) can help identify the source of elevation.

  • Aldolase:

    • Function: Aldolase is involved in carbohydrate metabolism in muscles.

    • Clinical Significance:

      • Elevated levels suggest muscle damage, particularly in conditions like myopathies and muscular dystrophies.

5. Prostate Disease

Enzymatic Markers:

  • Prostate-Specific Antigen (PSA):

    • Function: PSA is a protein produced by prostate gland cells.

    • Clinical Significance:

      • Elevated PSA levels can indicate prostate cancer, benign prostatic hyperplasia, or prostatitis.

      • It is used for screening and monitoring treatment efficacy for prostate cancer.

  • Acid Phosphatase (ACP):

    • Function: ACP is produced in several tissues, including the prostate.

    • Clinical Significance:

      • Though less commonly used today due to PSA availability, elevated ACP can signal prostate cancer.

6. Bone Diseases

Enzymatic Markers:

  • Alkaline Phosphatase (ALP):

    • Function: ALP is involved in bone mineralization.

    • Clinical Significance:

      • Elevated levels can indicate bone disorders including osteomalacia, Paget's disease, or bone metastases.

  • Tartrate-Resistant Acid Phosphatase (TRAP):

    • Function: TRAP is produced by osteoclasts, the cells that break down bone tissue.

    • Clinical Significance:

      • Elevated TRAP levels can indicate increased bone resorption, such as in osteoporosis or bone metastases.

  • Cholinesterase – Breaks down neurotransmitters. Reduced levels indicate liver disease or pesticide poisoning.

  • Glucose-6-Phosphate Dehydrogenase (G6PD) – Important in red blood cell metabolism. Deficiency can cause hemolytic anemia, especially after exposure to certain drugs or infections.

  • Ceruloplasmin – A ferroxidase enzyme that helps in copper metabolism. Reduced in Wilson’s disease (copper accumulation disorder) and elevated in inflammatory conditions.

Enzymatic markers serve as critical indicators of organ-specific damage or disease. By measuring the levels of these enzymes in blood, healthcare professionals can diagnose conditions, monitor the effectiveness of treatments, and assess disease progression. Understanding the clinical significance of each enzymatic marker helps guide appropriate medical interventions and improves patient outcomes.

Enzymes in Genetic Engineering & Industry

Genetic Engineering:

  • Restriction Endonucleases – Cut DNA for genetic manipulation.

  • Taq DNA Polymerase – Used in PCR (DNA amplification).

Industrial Uses:

  • Rennin – Used in cheese production.

  • Glucose Isomerase – Converts glucose into high-fructose corn syrup.

  • Proteases – Used in detergents for stain removal.

Definitions of Unfamiliar Terms

  • Biocatalyst – A substance (enzyme) that speeds up biochemical reactions.

  • Hydrolysis – Breaking down molecules using water.

  • Cholestasis – A condition where bile flow is blocked.

  • Myocardial Infarction – A heart attack due to blocked blood supply.

  • PCR (Polymerase Chain Reaction) – A technique to amplify DNA.

  • Ferroxidase (Ceruloplasmin) – An enzyme involved in iron metabolism.