Podcast
Questions and Answers
What distinguishes true isoenzymes from multiple forms of an enzyme?
What distinguishes true isoenzymes from multiple forms of an enzyme?
Which statement about lactate dehydrogenase (LDH) is correct?
Which statement about lactate dehydrogenase (LDH) is correct?
What is the role of post-translational modifications in enzyme variation?
What is the role of post-translational modifications in enzyme variation?
Which of the following is an example of multiple forms of an enzyme?
Which of the following is an example of multiple forms of an enzyme?
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Which subunit types are associated with creatine kinase (CK)?
Which subunit types are associated with creatine kinase (CK)?
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Which type of plasma enzymes are present in higher concentrations compared to tissues?
Which type of plasma enzymes are present in higher concentrations compared to tissues?
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What is the primary function of functional plasma enzymes?
What is the primary function of functional plasma enzymes?
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Which enzyme is typically associated with assessing blood diseases?
Which enzyme is typically associated with assessing blood diseases?
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What effect does liver disease have on the concentration of certain enzymes?
What effect does liver disease have on the concentration of certain enzymes?
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What is a consequence of increased permeability of the cell membrane?
What is a consequence of increased permeability of the cell membrane?
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Which of the following is NOT a typical site for the synthesis of non-functional plasma enzymes?
Which of the following is NOT a typical site for the synthesis of non-functional plasma enzymes?
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Which isoenzyme is primarily associated with myocardial infarction?
Which isoenzyme is primarily associated with myocardial infarction?
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Which enzyme is associated primarily with liver diseases?
Which enzyme is associated primarily with liver diseases?
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Which of the following conditions does creatine kinase (CK) increase in?
Which of the following conditions does creatine kinase (CK) increase in?
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Which factor can lead to enzyme release into the bloodstream?
Which factor can lead to enzyme release into the bloodstream?
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Which isoenzyme increases specifically with leukemia?
Which isoenzyme increases specifically with leukemia?
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What is one of the clinical significances of isoenzymes?
What is one of the clinical significances of isoenzymes?
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What disease is associated with an increase in lactate dehydrogenase enzyme?
What disease is associated with an increase in lactate dehydrogenase enzyme?
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What organ condition can be indicated by the rise of creatine kinase (CK)?
What organ condition can be indicated by the rise of creatine kinase (CK)?
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Which of the following conditions is NOT indicated by an increase in lactate dehydrogenase?
Which of the following conditions is NOT indicated by an increase in lactate dehydrogenase?
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Which isoenzyme would NOT be relevant for differentiating between brain diseases and skeletal muscle diseases?
Which isoenzyme would NOT be relevant for differentiating between brain diseases and skeletal muscle diseases?
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What is a characteristic of true isoenzymes?
What is a characteristic of true isoenzymes?
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Which of the following statements accurately describes lactate dehydrogenase (LDH)?
Which of the following statements accurately describes lactate dehydrogenase (LDH)?
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What defines the electrophoretic mobility of an enzyme?
What defines the electrophoretic mobility of an enzyme?
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Which of the following enzymes is characterized as a dimer?
Which of the following enzymes is characterized as a dimer?
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What is the primary form of creatine kinase (CK) found in the heart?
What is the primary form of creatine kinase (CK) found in the heart?
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What is one of the primary medical significances of lactate dehydrogenase in relation to diseases?
What is one of the primary medical significances of lactate dehydrogenase in relation to diseases?
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Which of the following conditions is associated with an increase in the enzyme serum glutamic pyruvic transaminase?
Which of the following conditions is associated with an increase in the enzyme serum glutamic pyruvic transaminase?
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How does liver disease affect the concentration of functional plasma enzymes?
How does liver disease affect the concentration of functional plasma enzymes?
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Which enzyme is likely elevated in both liver and heart diseases?
Which enzyme is likely elevated in both liver and heart diseases?
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Which enzyme is specifically related to detecting brain diseases?
Which enzyme is specifically related to detecting brain diseases?
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What is a common outcome of cell damage regarding enzyme presence in the blood?
What is a common outcome of cell damage regarding enzyme presence in the blood?
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Which of the following diseases is most likely indicated by elevated alkaline phosphatase?
Which of the following diseases is most likely indicated by elevated alkaline phosphatase?
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In which scenario would a non-functional plasma enzyme likely be present in higher concentration?
In which scenario would a non-functional plasma enzyme likely be present in higher concentration?
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Which disease is NOT indicated by an increase in lactate dehydrogenase (LDH)?
Which disease is NOT indicated by an increase in lactate dehydrogenase (LDH)?
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Creatine kinase (CK) is primarily associated with increases in which of the following conditions?
Creatine kinase (CK) is primarily associated with increases in which of the following conditions?
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Which isoenzyme is primarily used to diagnose heart diseases?
Which isoenzyme is primarily used to diagnose heart diseases?
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What is the significance of measuring isoenzymes in clinical settings?
What is the significance of measuring isoenzymes in clinical settings?
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Increases in creatine kinase (CK) levels can indicate which of the following diseases?
Increases in creatine kinase (CK) levels can indicate which of the following diseases?
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Which factor is NOT typically associated with an increase in creatine kinase (CK) levels?
Which factor is NOT typically associated with an increase in creatine kinase (CK) levels?
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Which condition indicates a significant increase in lactate dehydrogenase (LDH) levels?
Which condition indicates a significant increase in lactate dehydrogenase (LDH) levels?
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Study Notes
Biochemistry Lecture Notes
- Isoenzymes: Different molecular forms of an enzyme with the same catalytic activity but physically distinct. They differ in electrophoretic mobility (movement in an electric field) and susceptibility to inhibitors.
- Isoenzyme Sources: True isoenzymes result from true genetic variants, where different genes produce separate subunits. Multiple forms can arise from post-translational modifications of subunits from the same gene, leading to variations in different organs.
- Isoenzyme Examples: Lactate dehydrogenase (LDH), creatine kinase (CK), acid phosphatase, and alkaline phosphatase are examples of isoenzymes.
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LDH (Lactate Dehydrogenase): A tetramer of four protein subunits (protomer). It comes in five forms (LDH1-LDH5) designated by different combinations of H (heart) and M (muscle) subunits.
- LDH Function: Clinically important for differentiating heart, liver, and blood diseases. Increased levels often indicate problems like myocardial infarction or viral hepatitis.
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CK (Creatine Kinase): A dimer formed by two protein subunits. Isoenzymes include CK-BB (brain), CK-MB (cardiac/skeletal), and CK-MM (muscle).
- CK Function: Important for diagnosis, particularly in distinguishing brain, heart, and skeletal muscle diseases. Increased CK-MB activity can signify myocardial infarction.
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Plasma Enzymes:
- Functional Plasma Enzymes: Present in plasma at higher concentrations compared to tissues. They have known functions (e.g., clotting factors, lipoprotein lipase).
- Non-functional Plasma Enzymes: Exist in plasma at lower levels. They lack known functions in plasma.
- Clinical Significance: Decreased levels of certain enzymes in liver diseases correlate to liver damage or disease. Increased plasma levels often indicate problems like liver or heart disease, bone disease, and obstructive or other diseases. Different enzymes are elevated in varying diseases.
- Enzyme Classification (Non-functional): Functional plasma enzymes have known functions, measured in higher concentrations in plasma than in tissue. Non-functional enzymes have unknown functions; measured at low concentrations.
Medical Importance of Isoenzymes
- Isoenzymes Diagnostic Value: Isoenzymes are vital in diagnostics since they help pinpoint diseased organs in the body.
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LDH Isoenzymes and Diseases:
- LDH 1 & 2: Raised in myocardial infarction (heart attack), leukemia, and blood diseases.
- LDH 3: Elevated due to leukemia.
- LDH 4 & 5: High levels may indicate viral hepatitis (liver disease).
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CK Isoenzymes and Diseases:
- CK-BB: Increased activity points to brain tumors.
- CK-MB: Raised levels in myocardial infarction (heart attack).
- CK-MM: Elevated levels indicate skeletal muscle problems (e.g., muscle dystrophy).
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Other Plasma Enzymes and Diseases:
- SGPT/ALT (Alanine Transaminase): Indicates liver conditions.
- SGOT/AST (Aspartate Transaminase): Indicates liver, heart problems, and obstructive liver disease.
- Alkaline Phosphatase: Associated with bone and prostate conditions.
- Acid Phosphatase: Associated with different diseases, including prostate cancer.
- Amylase: Important for pancreatitis diagnosis.
- Lipase: Also pivotal in diagnosing pancreatitis.
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