Biochemistry Enzymes Overview
45 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which isoenzyme of aminotransferases is primarily derived from platelets, erythrocytes, and monocytes?

  • Band 5 Isoenzyme
  • Band 2 Isoenzyme
  • Band 3 Isoenzyme (correct)
  • Alanine Aminotransferase

    • What is the cofactor required for the activity of alanine aminotransferase?

  • Thiamine
  • NAD+
  • Folate
  • Pyridoxal-5'-phosphate (correct)

    • What is the primary function of aspartate aminotransferase?

  • Transfer of an amino group between aspartate and α-ketoacids (correct)
  • Breakdown of fatty acids
  • Synthesis of nucleotide precursors
  • Conversion of glutamate to proline

    • Which isoenzyme is mentioned as being resistant to tartrate inhibition?

    <p>Band 5 Isoenzyme</p> Signup and view all the answers

    In which condition is positive ACP evident in a vaginal swab within the first 12 hours up to four days?

    <p>Prostatic massage</p> Signup and view all the answers

    What is the ideal pH range for most physiological reactions to occur?

    <p>pH 7-8</p> Signup and view all the answers

    Which temperature is recommended for the storage of substrates and coenzymes?

    <p>2-8 degrees Celsius</p> Signup and view all the answers

    What type of enzyme inhibitor competes with the substrate for the active site?

    <p>Competitive inhibitor</p> Signup and view all the answers

    What is a disadvantage of measuring enzyme activity at the end of the reaction?

    <p>Underestimation of true enzyme activity</p> Signup and view all the answers

    In multi-point assays, how is the concentration of the indicator substance measured?

    <p>At several intervals</p> Signup and view all the answers

    Which of the following best describes uncompetitive inhibition?

    <p>Binds only to the enzyme-substrate complex</p> Signup and view all the answers

    What is the unit commonly used for expressing enzymatic activity?

    <p>International Unit (I.U.)</p> Signup and view all the answers

    What effect does hemolysis have on enzyme concentration measurements?

    <p>Increases enzyme concentration</p> Signup and view all the answers

    What is the primary physiological role of Alkaline Phosphatase (ALP)?

    <p>Cleavage of phosphate-containing compounds in alkaline conditions</p> Signup and view all the answers

    Which condition is NOT associated with elevated levels of ALP?

    <p>Cirrhosis of the liver</p> Signup and view all the answers

    Regan ALP, a variant of alkaline phosphatase, is primarily found in which type of cancers?

    <p>Lung and breast cancers</p> Signup and view all the answers

    Decreased serum levels of ALP are indicative of which condition?

    <p>Hypophosphatasia</p> Signup and view all the answers

    Which ALP variant is specifically associated with adenocarcinoma of the pancreas?

    <p>Nagao ALP</p> Signup and view all the answers

    Which of the following substances is known to inhibit Regan ALP?

    <p>Phenylalanine</p> Signup and view all the answers

    The most heat-stable variant of ALP is which type?

    <p>Regan ALP</p> Signup and view all the answers

    What are common conditions that can lead to elevated levels of ALP?

    <p>Hepatocellular carcinoma and lung cancer</p> Signup and view all the answers

    Which tissue is a major source of mitochondrial AST?

    <p>Cardiac tissue</p> Signup and view all the answers

    In which condition would you expect an increase in both AST and ALT levels?

    <p>Muscle injury</p> Signup and view all the answers

    What is a reference range for AST levels?

    <p>5-37 U/L</p> Signup and view all the answers

    Which of the following conditions can lead to decreased AST levels?

    <p>Pregnancy</p> Signup and view all the answers

    What is the role of creatine kinase (CK) in muscle metabolism?

    <p>Facilitates reversible phosphorylation of creatine by ATP</p> Signup and view all the answers

    During periods of active muscle contraction, what happens to creatine phosphate?

    <p>It is converted to creatine and ATP</p> Signup and view all the answers

    Which enzyme is specifically noted for being a bone isoenzyme?

    <p>ACP</p> Signup and view all the answers

    What typically causes an increase in AST levels by 4-10 times the upper limit of normal?

    <p>Myocardial infarction</p> Signup and view all the answers

    What enzyme is primarily associated with the conversion of angiotensin I to angiotensin II?

    <p>Angiotensin-Converting Enzyme</p> Signup and view all the answers

    Which enzyme is rarely used but considered an excellent marker for liver disease?

    <p>Ornithine carbamoyl transferase</p> Signup and view all the answers

    What typically leads to an elevation of Angiotensin-Converting Enzyme levels?

    <p>Pulmonary involvement in sarcoidosis</p> Signup and view all the answers

    What is the most common reason for testing pseudocholinesterase activity?

    <p>Assessing sarcoidosis</p> Signup and view all the answers

    In which organ is pseudocholinesterase predominantly found?

    <p>Lungs</p> Signup and view all the answers

    What structural characteristic is associated with cholinesterase?

    <p>Single polypeptide chain with zinc at the active center</p> Signup and view all the answers

    Which condition is associated with low activity of cholinesterase enzymes?

    <p>Malnutrition</p> Signup and view all the answers

    What happens to the activity of Angiotensin-Converting Enzyme as fibrosis progresses?

    <p>It declines</p> Signup and view all the answers

    What is the primary function of Gamma-Glutamyl Transferase (GGT)?

    <p>Transfer of glutamyl moiety from peptides to amino acids, other peptides, or water</p> Signup and view all the answers

    Which condition is GGT considered a very sensitive indicator for?

    <p>Acute myocardial infarction</p> Signup and view all the answers

    In which tissue does GGT predominantly reside as plasma membrane bound?

    <p>Liver and proximal renal tubules</p> Signup and view all the answers

    What is the typical half-life of GGT in healthy individuals?

    <p>7 to 10 days</p> Signup and view all the answers

    Which of the following conditions is NOT associated with elevated GGT levels?

    <p>Malignant hyperthermia</p> Signup and view all the answers

    What effect does smoking have on GGT levels?

    <p>Moderate smoking raises levels by 10% and heavy smoking by 20%</p> Signup and view all the answers

    Which of the following is the reference value range for GGT in males?

    <p>6 - 45 U/L</p> Signup and view all the answers

    Which of the following diseases would most likely lead to the highest elevation of total CK levels?

    <p>Duchenne muscular dystrophy</p> Signup and view all the answers

    Study Notes

    Enzymes

    • Specific biologic proteins catalyze biochemical reactions without altering the equilibrium point.
    • Appear in serum after cellular injury, degradation of cells, or storage areas.
    • High amounts of enzymes in serum indicate organ damage.

    Terms Associated with Enzymes

    • Holoenzyme: Active substance formed by a coenzyme (cofactor) and apoenzyme.
    • Apoenzyme: Protein portion of an enzyme; subject to denaturation, losing activity if cofactor is removed.
    • Isoenzyme: Different forms of the same enzyme with the same catalytic function in the body.
    • Metalloenzyme: Enzyme with metal ions intrinsically part of the molecule (e.g., catalase, cytochrome oxidase).
    • Proenzyme: Inactive precursor of enzymes, also called zymogens.
    • Substrates: Substances acted upon by the enzyme; specific to each enzyme.
    • Cofactors: Non-protein substances needed for enzyme activity (e.g., thermostable and dialyzable). Enzymes require these before manifesting enzymatic activity.

    Enzyme Nomenclature

    • Practical/Trivial Name: Based on the substrate name with the suffix "ase" (e.g., lipase for lipids, protease for proteins).
    • Systematic Name: Based on the numerical designation given by the Enzyme Commission (EC).
    • Examples: EC 1.1.1.7 for lactate dehydrogenase; EC 3.2.1.1 for amylase.

    Enzyme Kinetics

    • Enzyme–Substrate Interaction: An enzyme binds to a substrate to form an enzyme-substrate complex (ES). The complex can dissociate back to enzyme (E) and substrate (S). Alternatively, the complex breaks down to product (P) and free enzyme (E) if the product has a low affinity for the enzyme.
    • Types of Specificity:
      • Absolute Specificity: Enzymes combine with only one substrate.
      • Group Specificity: Enzymes combine with all substrates containing a particular group.
      • Bond Specificity: Enzymes combine with specific chemical bonds.
      • Stereoisomeric Specificity: Enzymes combine primarily with one optical isomer.

    Factors Affecting Enzyme Reactions

    • Enzyme Concentration: Increased enzyme concentration yields increased reaction rate.
    • Substrate Concentration: Increased substrate concentration increases reaction rate up to a maximum rate.
    • Temperature: Reaction rate increases with temperature, approximately doubling for every 10°C rise.
    • pH: Optimum pH exists for each enzyme; deviation from the optimum slows reactions.

    Types of Reaction Order

    • Zero-Order Reaction: Reaction rate is independent of substrate concentration and directly proportional to enzyme concentration.

    General Classification of Enzymes

    • Oxidoreductases: Catalyze redox (reduction-oxidation) reactions (removal or addition of electrons).
    • Transferases: Catalyze the transfer of a chemical group from one substrate to another.
    • Hydrolases: Catalyze hydrolysis reactions (the splitting of a bond by the addition of water).
    • Lyases: Remove groups from substrates without hydrolysis, creating double bonds.
    • Isomerases: Catalyze intramolecular rearrangements of substrates.
    • Ligases (Synthetases): Join two substrate molecules together using energy from a high-energy phosphate.

    Enzyme Inhibition

    • Competitive Inhibition: Inhibitor competes with the substrate for the active site.
    • Non-competitive Inhibition: Inhibitor binds to the enzyme at a site other than the active site (allosteric site).
    • Uncompetitive Inhibition: Inhibitor binds to the enzyme-substrate complex.

    Enzyme Induction

    • Enzyme induction is the ability of an enzyme to adapt to biochemical systems.

    Clinical Enzymology (Additional Topics)

    • Room temperature: Ideal for storing LDH (LD4 and LD5).
    • Hemolysis: Increase of enzyme concentration.
    • Lactescence/milky specimens: Decrease in enzyme concentration.
    • Measurement of enzyme activity: Done at the end of a reaction, usually in combination with colorimetric reaction.
    • Units for expressing enzymatic activity: International Units (IU) or katal units (KU).
    • Means of measuring enzyme activity: Change in coenzyme concentration; Increase in product concentration; Decrease in substrate concentration.
    • Specific enzyme examples (e.g., Alkaline Phosphatase, Acid Phosphatase (ACP), Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), Creatine Kinase (CK), Gamma-Glutamyl Transferase (GGT), Leucine Aminopeptidase (LAP), 5’ Nucleotidase (5'N), Ornithine Carbamoyl Transferase (OCT), Cholinesterase, Pseudocholinesterase, Angiotensin-Converting Enzyme (ACE), Myeloperoxidase, Aldolase, Lactate Dehydrogenase (LDH), Amylase or Diastase), their properties, and diagnostic significance.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Clinical Enzymology CC LEC - MED226 PDF

    Description

    This quiz covers the fundamental concepts of enzymes, including their functions, types, and associated terms. Explore key enzyme definitions such as holoenzyme, apoenzyme, isoenzyme, and more, to deepen your understanding of biochemical reactions and organ damage indicators.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser