Plasma Enzymes Classification

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Questions and Answers

What is the primary characteristic of functional plasma enzymes?

Normally present in serum in low activities

Do not have any function in plasma

Present in tissues at higher concentration than plasma

Present in plasma at higher concentration than tissues (correct)

What is the primary factor in selecting an enzyme to test for a disease?

The distribution of enzymes among various tissues (correct)

The activity of enzymes in serum

The function of enzymes in plasma

The concentration of enzymes in plasma

Which of the following enzymes is an example of a non-functional plasma enzyme?

Lipoprotein lipase

Creatine kinase (correct)

Clotting enzymes

Ornithine carbamyltransferase

What is the liver: blood ratio of an enzyme that should make it a readily detectable elevation in blood levels?

100,000:1 Signup and view all the answers

What is the significance of measuring changes in the activities of non-functional plasma enzymes in disease?

To infer the location and nature of pathological changes in tissues Signup and view all the answers

Which of the following enzymes is rapidly inactivated on entering the vascular compartment after a myocardial infarction?

Isocitrate dehydrogenase Signup and view all the answers

Why is a particular enzyme not used in clinical enzymology despite its potential?

Inconvenience of the assay and lack of clinical experience Signup and view all the answers

What is the characteristic of ornithine carbamyltransferase?

It is a liver-specific enzyme Signup and view all the answers

Which of the following enzymes is primarily sourced from the prostate and RBCs?

Acid phosphatase Signup and view all the answers

What is a key factor in selecting enzymes for clinical enzymology?

All of the above Signup and view all the answers

What is the significance of non-functional plasma enzymes in clinical chemistry?

They are used to infer the location and nature of pathological changes in tissues Signup and view all the answers

Which enzyme is commonly used in the diagnosis of pancreatic diseases?

Amylase Signup and view all the answers

Which of the following enzymes is synthesized by the liver, skeletal muscle, heart, and brain?

Alanine transaminase Signup and view all the answers

Which of the following enzymes is specific to the liver?

Cholinesterase Signup and view all the answers

What is the primary application of Aspartate aminotransferase (AST)?

Myocardial infarction and hepatic parenchymal disease Signup and view all the answers

What is the main factor affecting enzyme activity?

The presence of inhibitors or activators Signup and view all the answers

What is the criteria for selecting enzymes for testing in clinical enzymology?

The enzyme's ability to detect tissue damage or disease Signup and view all the answers

What is the main reason why enzyme activity is easier to measure than protein concentration?

Enzyme activity can be determined by changes in substrate or product concentrations Signup and view all the answers

What is the definition of clinical enzymology?

The measurement of enzymes in body fluids for disease diagnosis and monitoring Signup and view all the answers

What is the primary purpose of measuring enzyme activity in plasma?

To detect and localize tissue cell damage or proliferation Signup and view all the answers

Which of the following enzymes is used in the diagnosis of organophosphorus insecticide poisoning?

Cholinesterase Signup and view all the answers

What is the term for multiple forms of an enzyme that catalyze the same reaction?

Isoenzymes Signup and view all the answers

Study Notes

Plasma Enzymes

Plasma enzymes can be classified into two types: functional and non-functional plasma enzymes
Functional plasma enzymes are present in plasma at higher concentrations than in tissues and function in plasma
They are mostly synthesized by the liver and usually decrease in disease conditions
Examples of functional plasma enzymes include clotting enzymes and lipoprotein lipase

Non-Functional Plasma Enzymes

Non-functional plasma enzymes are present in tissues at higher concentrations than in plasma and do not have any function in plasma
They are mostly synthesized by the liver, skeletal muscle, heart, and brain
They usually increase in disease conditions
Examples of non-functional plasma enzymes include creatine kinase and alanine transaminase
Measurement of these enzymes in plasma can be used to assess cell damage and proliferation, i.e., diagnosis of disease

Criteria for Selection of Enzyme Tests

The selection of enzyme tests depends on the distribution of enzymes among various tissues
Not all intracellular enzymes are equally valuable as indicators of cellular damage
Other factors, such as rate of disappearance from blood, ease of assay, cost of assay, and quantity in blood, also define the enzymes of clinical interest

Distribution of Diagnostically Important Enzymes

Acid phosphatase: prostate, RBCs; principal clinical application: carcinoma of prostate
Alanine aminotransferase (ALT): liver, skeletal muscle, heart; principal clinical application: hepatic parenchymal disease
Aldolase: skeletal muscle, heart; principal clinical application: muscle diseases
Amylase: salivary glands, pancreas, ovaries; principal clinical application: pancreatic diseases
Aspartate aminotransferase (AST): liver, skeletal muscle, heart, kidney, RBCs; principal clinical application: myocardial infarction, hepatic parenchymal disease, muscle disease
Cholinesterase: liver; principal clinical application: organophosphorus insecticide poisoning, hepatic parenchymal diseases
Creatine kinase (CK): skeletal muscle, brain, heart, smooth muscle; principal clinical application: myocardial infarction, muscle diseases
g-Glutmyltransferase (GGT): liver, kidney; principal clinical application: hepatobiliary disease, alcoholism
Lactate dehydrogenase (LDH): heart, liver, skeletal muscle, RBCs, platelets, lymph nodes; principal clinical application: myocardial infarction, haemolysis, hepatic parenchymal diseases

Clinical Enzymology

Clinical enzymology is the measurement of some selected enzymes in specimens (usually of blood, especially plasma) for detection and monitoring of diseases
Changes in plasma enzyme activities help to detect and localize tissue cell damage or proliferation, or to monitor treatment and progress of disease

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Description

Learn about the classification of plasma enzymes into functional and non-functional types, their characteristics, and examples of each.