Enzymes: Isozymes and Regulation

Objectives

Enzymes: Isozymes and Regulation

1. Define isozyme and nonfunctional plasma enzyme and discuss the importance of nonfunctional plasma enzymes as a diagnostic tool.

2. Identify the brain, muscle, heart and liver isozyme patterns for creatine phosphokinase and lactate dehydrogenase.

3. Describe how creatine phosphokinase and lactate dehydrogenase can be used in the diagnosis of myocardial infarction.

4. Explain why a combined analysis of plasma glutamyl transpeptidase and alanine aminotransferase is desirable for diagnosing hepatitis in a patient.

5. Define the following types of regulation of enzyme activity: substrate availability, allostery, post-translational modification, interactions with control proteins and zymogens.

6. List 6 ways that proteins can undergo post-translational modification.

7. Identify the 3 amino acids which can undergo phosphorylation.

Enzyme Mechanisms-Serine Proteases

1. Describe the general roles played by the serine, histidine and aspartate residues in the active site of chymotrypsin.

2. Explain why histidine is found in the active site of many diverse proteases.

3. Diagram the catalytic mechanism of chymotrypsin, identifying the two transition states.

4. Give two examples of other serine proteases and their general physiological role.

5. Define the term proenzyme and give an example of a physiological role for proenzymes.

Overview of Nutrients

1. Define: essential nutrient, protein quality, ideal protein, essential amino acid, biological value, vitamin.

2. List the forms and identifying characteristics of each of the forms of malnutrition.

3. List and define the energy providing nutrients, their major functions in the body and the number of calories (Kcal) furnished by each.

4. Discuss the significance of ethanol as fuel and low vs. high alcohol intake.

5. For each of the 9 water soluble vitamins, list:

(a) major function(s)

(b) RDA (recommended daily allowance).

Case Study 3

Diagram the time course for the appearance in serum of creatine kinase, lactate dehydrogenase and aspartate amino transferase following a myocardial infarction.

Vitamins of Carbohydrate and Nitrogen Metabolism

1. Explain how nicotinamide adenine dinucleotide (NAD+) and nicotinamide adenine dinucleotide phosphate (NADP+) containing enzymes function in energy producing pathways.

2. Explain how flavin adenine dinucleotide (FAD) containing enzymes function in energy producing pathways.

3. List key metabolic pathways in which NAD+, NADP+ and FAD participate.

4. Compare and contrast dietary and metabolic sources of niacin and riboflavin.

5. Identify the key metabolic pathways in which vitamin B6 dependent enzymes participate.

6. Distinguish between the dietary and co-enzyme forms of niacin, riboflavin and pyridoxal (pyridoxine).