Lecture 11 Enzymes-3 (Enzymes in clinical diagnosis) Biochemistry Year 1 PDF

# Biochemistry for Year 1 Students (HBF-102) ## Lecture: Enzyme III ### **Faculty of Medicine** * **Academic Year:** 2024-2025 * **Year:** 1 * **Semester:** 1 * **Module:** Human Body Function (HBF) 102 ### **[Faculty Logo]** ### **Professors:** * Prof. Dr. Mohamed I. Kotb * Ass. Prof. Dr. Ah...

# Biochemistry for Year 1 Students (HBF-102) ## Lecture: Enzyme III ### **Faculty of Medicine** * **Academic Year:** 2024-2025 * **Year:** 1 * **Semester:** 1 * **Module:** Human Body Function (HBF) 102 ### **[Faculty Logo]** ### **Professors:** * Prof. Dr. Mohamed I. Kotb * Ass. Prof. Dr. Ahmed M. A. Akabawy ### **Department:** * Biochemistry & Molecular Biology department * Faculty of Pharmacy, Helwan University ## **Enzymes III** ### **Enzymes in Clinical Diagnosis** ### **By:** * Prof. Dr. Mohammed Kotb & Assoc. * Prof. Dr. Ahmed M. A. Akabawy ## **Objectives** 1. Analyze types of plasma enzymes 2. Recognize enzymes important in clinical diagnosis 3. Identify diagnostic biomarkers important in Myocardial infarction ## **Introduction** ### **Plasma Enzymes** * **Definition** * **Types** * **Biological Importance** * **Myocardial Infarction** * **Biomarkers of MI** ## **Types of Plasma Enzymes** A diagram shows Plasma Enzymes divided into Functional and Non-Functional. * **Functional** * Have Known function in the plasma * As: Clotting factors * **Non-Functional** * Have No function in the plasma * Released into plasma * During cell turnover * From some damaged organs * As: Transaminases ## **Non-functional Plasma Enzymes in Health & Disease** A diagram shows a normal cell, damaged tissue, cell death, enzyme release, normal enzyme activity, blood stream, and elevated enzyme activity. ## **Isoenzymes** * **Definition:** Multiple forms of the same enzyme catalyzing the same reaction but differ in their molecular structure, chemical characteristics of the reaction condition according to tissue localization. * **Examples:** LDH, CK, ACP, ALP * **Determination:** Determination of them in plasma is a very useful diagnostic tool that helps to identify the location & severity of a disease. ## **Analyzing Plasma Enzymes** * **Definition:** Performing an assay for plasma enzyme(s) in blood with the aim of diagnosis or monitoring a clinical condition. ## **Why Plasma Enzymes are Important in Clinical Diagnosis?** A diagram shows blood vessels and cells with enzymes. The diagram highlights the small amounts of intracellular enzymes present in the blood as a result of normal cell turnover. The diagram also highlights the increased amounts of enzymes that are released with tissue damage. ## **Important Plasma Enzymes useful in Clinical Diagnosis** 1. Lactate dehydrogenase (LDH) 2. Creatine Kinase (CK) 3. Aminotransferases (ALT “SGPT” & AST “SGOT”) 4. Phosphatases (Alkaline phosphatase, Acid phosphatase). 5. Gamma glutamyl transferase & 5' nucleotidase. ## **Lactate Dehydrogenase (LDH)** 1. **Tetrameric protein** made of two types of subunits namely (H= heart, M= skeletal muscle) 2. **Catalyzes** the conversion of Lactate to Pyruvate. 3. **Re-oxidation** of NADH,H+ into NAD A diagram shows a chemical reaction with: * Lactate * Lactate dehydrogenase * Pyruvate * NAD * NADH + H+ ## **LDH (5 Isoenzymes)** |Isoenzyme|Composition|Present in|Elevated in| |---|---|---|---| |LDH1|HHHH (H4)|Myocardium, RBCs|Myocardial infarction| |LDH2|HHHM (H3M)|Myocardium, RBCs|---| |LDH3|HHMM (H2M2)|Lung|Lung disease| |LDH4|HMMM (HM3)|Kidney, pancreas|Kidney, pancreas disorders| |LDH5|MMMM(M4)|Liver, Skeletal muscles |Liver disease| A diagram shows a comparison chart: * LDH Isoenzymes * Heart * RBCs * Liver ## **LDH** 1. **LDH-1 and LDH-2** are both associated with **cardiac and blood cells origin**. 2. **Normally**, serum level of LDH-2 is greater than LDH-1 BUT in case of myocardial infarction, a flip or inversion of the LDH-1:LDH-2 ratio occurs (LDH-1>LDH-2) known as **flipped pattern**. * **The diagnostic ratio of LDH-I/LDH-II** * **Normally** less than 0.9 **BUT** In MI, changed to greater than 0.9. ## **Creatine Kinase (CK)** **Dimeric protein** , 2 types of subunits **B (Brain), M (Muscle).** |Isoenzyme|Composition|Present in| Elevated in| |---|---|---|---| |CK1|BB|Brain |Brain diseases| |CK2|MB|Heart|Myocardial infarction| |CK3|MM|Skeletal muscle |Skeletal muscle diseases| A diagram shows a complex chemical reaction with: * Creatine * ADP * ATP * Creatine Kinase * Phosphocreatine * Muscle * Blood * Rapid source of energy in the cell ## **CK** * **CK-MB** is present in large quantities in the **myocardium** * **Serum levels** increase within **3-6 hrs of the chest pain onset (Rapid onset).** ## **Transaminases (ALT "GPT"& AST "GOT")** 1. **ALT** is an enzyme found primarily in the liver cells (Cytosolic) . 2. **AST** is an enzyme found mainly in the liver cells **AST2** (Mitochondrial) & in heart muscle **AST1** (cytosolic) * **Asp** + **a-ketoglutarate** <-> **Asp amino-transferase** <-> **OAA** + **Glu** * **Ala** + **a-ketoglutarate** <-> **Ala amino-transferase** <-> **pyruvate** + **Glu** 3. **AST and ALT levels** are frequently compared and interpreted for **diagnostic purposes:-** A diagram shows three arrows indicating the direction of increasing values: * **ALT >>> AST** * **Acute hepatitis** * **Liver necrosis** * **AST >>> ALT** * **Chronic hepatitis** * **Cirrhosis** * **Liver Cancer** * **AST** * **Myocardial damage (Acute M.I)** ## **Transaminases (ALT "GPT"& AST "GOT")** A diagram shows a simplified schematic of the liver, gallbladder, stomach, pancreas, duodenum. * **Liver** * **Hepatic Ducts** * **Gallbladder** * **Duodenum** * **Common Bile Duct** * **Major Duodenal Papilla** * **Stomach** * **Pancreas** * **Pancreatic Duct** ## **Phosphatases** * **Enzymes that remove a phosphate group from its substrate** |Phosphatase|pH| |---|---| |Alkaline Phosphatase (ALP)|9-10.5| |Acid Phosphatase (ACP)|5-6 | ## **Alkaline Phosphatase (ALP)** |Isoenzyme|Present in|Elevated in| |---|---|---| |Liver form|Biliary tract|Cholestasis | |Bone form|Bones (Osteoblast)|Bone diseases e.g. rickets, osteomalacia, neoplastic diseases with bone metastasis, healing fractures | * **Total ALP** PHYSIOLOGICALLY increased in **children** (Inc. in bone turnover) and **pregnancy** (Inc. in placental ALP). ## **Acid Phosphatase (ACP)** |Isoenzyme|Present in|Elevated in| |---|---|---| |Erythrocytic or lysosomal forms|Show wide spread distribution in most cells.|Harmful quantities of certain fatty substances accumulate in the spleen, liver, lungs, bone marrow and sometimes brain.| |Prostatic or macrophagic forms|Prostate|Benign prostatic hyperplasia and in prostate cancer| * **Prostatic ACP** -> Major significance ## **Gamma-glutamyl transferase “GGT”** * **GGT** helps diagnose liver disease and/or liver bile duct issues * **↑ Alcoholic hepatitis** * **↑ Bile duct obstructions** * **ALT, AST, ALP, GGT, Bilirubin= Used collectively to confirm diagnosis** * **↑ALP, ↑GGT, ↑Direct Bilirubin** -> **Bile duct obstructions** * **↑ALP, normal GGT, normal Bilirubin** -> **Bone disease** ## **5'-nucleotidase** 1. **5'-nucleotidase (5'-NT)** is a protein produced by the liver. 2. **A test can be done** to measure the amount of this protein in blood to reflect liver status. * **Cirrhosis** (scarring of the liver and poor liver function) * **Flow of bile from the liver is blocked (cholestasis)** ## **Objectives** 1. Analyze types of plasma enzymes 2. Recognize enzymes important in clinical diagnosis 3. Identify diagnostic biomarkers important in Myocardial infarction ## **Myocardial Infarction** * **Decrease** the blood supply to the myocardium that leads to **Ischemia**. * **Prolonged Ischemia** -------------> **Infarction** (Irreversible condition) A diagram shows a schematic comparing a healthy heart to a heart with blocked blood flow. * **A)** Heart muscle * **B)** * **Coronary artery** * **Blocked blood flow** * **Plaque buildup in artery** * **Healthy heart muscle** * **Blood clot blocks artery** * **Dead heart muscle** ## **Myocardial Infarction Pathophysiology** A diagram shows the following steps with arrows: * **Atherosclerosis, Arterial Spasm, Atherosclerosis+Plaque Split+Thrombus** * **Gradual Obstruction** * **Sudden reversible obstruction** * **Sudden not usually reversible occlusion** * **Ischemia, Hypoxia** * **Reduced Oxygen demand** * **Thrombolysis** * **Permanent thrombus** * **Necrosis** * **Angina** * **Unstable Angina** * **Myocardial Infarction** ## **MI** A diagram with arrows: * **Atherosclerotic plaques classically rupture leading to thrombosis** * **Decreased blood flow in the coronary** * **Reversible** * **Irreversible** * **Ischemia** * **Prolonged Ischemia** * **Infarction** * **O2 supply < O2 demand** ## **Risk Factors for MI** ### **Non Modifiable** * **Sex** (greater in men than in women) * **Age** (increases with increasing age). * **Family history** ### **Modifiable Risk Factors** * **Smoking** * **Dyslipidemia** * **Diabetes mellitus** * **Hypertension** * **Obesity** * **Sedentary lifestyle** * **Presence of peripheral vascular disease** ## **Symptoms of MI** A diagram shows a simplified schematic of a person experiencing chest discomfort, trouble breathing, and a light-headed feeling. * **Chest discomfort** * **Trouble breathing, with or without chest discomfort** * **Feeling light-headed or breaking into a cold sweat** * **Feeling sick or discomfort in your stomach** * **Pain described as** * **Aching** * **Crushing** * **Squeezing** * **Tightness** * **Heaviness** * **Pressure** ## **Cardiac Biomarkers for AMI** |Isoenzyme|Onset|Peak|Return to Baseline| |---|---|---|---| |LDH1|12-24 hrs Delayed|2-3 days|5-10 days| |CK MB|3-6 hrs Rapid|24 hrs|3-4 days| |AST1|After CK|48 hrs|5 days| * **Other cardiac biomarkers but not isoenzymes** * **Troponin I** * **Within 6 hrs** * **48 hrs** * **1-14 days** * **Myoglobin (non-specific)** * **2-6 hrs** * **12 hrs** * **24-36 hrs** ## **Troponins** * **Contractile proteins** in heart muscle * **Cardiac troponin I and T** * **Very sensitive and specific indicators for cardiac muscle damage** * **Levels elevated above the reference range, reflect heart muscle damage** ## **Interactive Question** **Which of the following best defines isoenzymes?** A) Enzymes that catalyze different reactions. B) Different forms of an enzyme that catalyze the same reaction. C) Enzymes that function only in the liver. D) Enzymes involved in protein synthesis. **Which enzyme is commonly used as a cardiac biomarker to diagnose myocardial infarction?** A) Amylase B) Alkaline phosphatase C) GGT D) Creatine kinase-MB (CK-MB) **Which cardiac enzyme is the most sensitive and specific biomarker for detecting a heart attack in the early stages?** A) Myoglobin B) Creatine kinase (CK) C) Troponin D) Lactate dehydrogenase (LDH) **Which of the following enzymes is most commonly used to diagnose liver cell damage in clinical practice?** A) Amylase B) Alkaline phosphatase (ALP) C) Alanine aminotransferase (ALT) D) Creatine kinase (CK) **Which enzyme is typically elevated in cholestasis, a condition where bile flow is impaired?** A) Gamma-glutamyl transferase (GGT) B) Lactate dehydrogenase (LDH) C) Aspartate aminotransferase (AST) D) Creatine kinase (CK) **Which of the following is a common enzyme pattern seen in acute hepatitis or liver injury?** A) ALT > AST B) AST > ALT C) ALP > GGT D) LDH > GGT **Elevated levels of which enzyme are commonly associated with chronic alcoholic hepatitis?** A) Gamma-glutamyl transferase (GGT) B) Aspartate aminotransferase (AST) C) Alkaline phosphatase (ALP) D) Alanine aminotransferase (ALT) **Which of the following is a clinical use of acid phosphatase (ACP) in diagnostics?** A) To diagnose liver damage B) To diagnose prostate cancer C) To evaluate bone metabolism D) To assess kidney function **What is the importance of 5'-nucleotidase, ALP, and bilirubin in distinguishing between liver and bone disease?** **How to use ALT/AST ratio in differential diagnosis of liver and cardiac diseases?** ## **References** * **Lippincott Illustrated Reviews: Biochemistry (Lippincott Illustrated Reviews Series) 7th Edition.** * **Lehninger Principles of Biochemistry Sixth Edition by David L. Nelson (Author), Michael M. Cox (Author).** * **Harper’s Illustrated Biochemistry, 32nd Edition, Peter J. Kennelly, Kathleen M. Botham, Owen P. McGuinness, Victor W. Rodwell, P. Anthony Weil.** *** * **Biochemistry** - The study of chemical processes within and relating to living organisms. * **Enzyme** - A substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction. * **Clinical Diagnosis** - The process of determining the nature and cause of a patient's illness. * **Myocardial Infarction** - A heart attack, occurs when blood flow to a part of the heart is blocked. * **Isoenzyme** - A form of an enzyme that has a slightly different structure and function from other forms of the same enzyme. * **Cholestasis** - A condition where bile flow from the liver is blocked. * **Chronic Alcoholic Hepatitis** - A condition characterized by inflammation of the liver due to long-term alcohol abuse. * **Acid Phosphatase** - An enzyme found in the prostate gland, and other tissues. * **Gamma-glutamyl Transferase** - An enzyme found in the liver and other tissues, elevated in liver disease. * **5'-Nucleotidase** - An enzyme found in the liver, elevated in liver disease. * **Bilirubin** - A yellow pigment produced by the breakdown of red blood cells, elevated in liver disease. * **ALT** - Alanine aminotransferase, an enzyme found in the liver. * **AST** - Aspartate aminotransferase, an enzyme found in the liver and other tissues. * **ALP** - Alkaline phosphatase, an enzyme found in the liver and other tissues. * **CK-MB** - Creatine kinase-MB, an enzyme found in the heart. * **Troponin** - A protein found in the heart muscle. * **Myoglobin** - A protein found in muscle tissue. The document is a lecture slide deck on Enzymes in Clinical Diagnosis for first-year biochemistry students. The document covers the types of plasma enzymes, the importance of enzymes in clinical diagnosis, specific enzymes useful in clinical diagnosis, and specific examples of how these enzymes are used to diagnose various diseases such as myocardial infarction and liver disease. The document concludes with interactive questions that challenge the students to apply their knowledge.