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CAS PS 333 Lecture Notes - Lecture 6: Grapefruit Juice, Alcohol Dehydrogenase, Disulfiram

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wm2001
21 Oct 2022
School
Boston University
Department
Psychological & Brain Sciences
Course
CAS PS 333
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Document Summary

Enzymes break down the drug into other compounds: e. g. alcohol dehydrogenase ( ase = enzyme) see slide 4. Metabolites prepared for excretion in urine or stool. Stimulation of enzyme systems: e. g. alcohol, induction of alcohol-metabolizing enzymes leads to metabolic tolerance. Depression of enzyme systems: disulfiram (antabuse) used to prevent drinking because. Cytochrome: substances in grapefruit juice block this enzyme, which is involved in breakdown of many drugs, increase bioavailability in blood interferes with enzymes that break it down. After being broken down by liver enzymes, most drugs are eliminated via urinary excretion by the kidneys: to get into urine, a substance must be water soluble. Kidneys filter everything out of your blood and they take all the things they like back they get rid of the toxins. Half-life- an index of how long the process from absorption to elimination takes:

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Related Questions

Can you please help with this assignment? This is all the professor has given to us and I am stuck.

Acid-Base Imbalances

Diabetic ketoacidosis

Prolonged vomiting

Barbiturate poisoning

Emphysema

Antacid overdose

Hyperventilation

Thoracic or abdominal surgery

Kidney failure

H+ high

H+ low

pH high

pH low

Respiratory acidosis

Respiratory

alkalosis

Metabolic acidosis

Metabolic alkalosis

Respiratory compensation by hyperventilation

Respiratory compensation by hypoventilation

Renal compensation by H+ excretion

Renal compensation by H+ reabsorption

Instructions for completing the Acid/Base Imbalance Worksheet

  1. In each vertical column, there is a list of illnesses or conditions.
  2. It the horizontal column are a list of descriptions.
  3. Place an “X” in the box that best describes each illness or condition.
  4. For example, look at the Diabetic Ketoacidosis column.
    1. Place an X in the first box if the H+ is high.
    2. Place an X in the second box if the H+ is low.
    3. Place an X in the third box if the pH would be high.
    4. Place an X in the fourth box if the pH would be low.
    5. Place an X in the fifth box if diabetic ketosis is a respiratory acidosis condition.
    6. Place an X in the sixth box if diabetic ketoacidosis is a respiratory alkalosis condition.
    7. Place an X in the seventh box if this condition is a metabolic acidosis condition.
    8. Place an X in the eighth box if this condition is a metabolic alkalosis condition.
    9. Continue down the column until you have marked an X in each box that applies to diabetic ketoacidosis.
  5. Each vertical column will have exactly 4 X’s.
Do Enzymes Physically Attach to Their Substrates?
 
When scientists first began to examine the chemical activities of organisms, no one knew that biochemical reactions were catalyzed by enzymes. The first enzyme was discovered in 1833 by French chemist Anselme Payen. He was studying how beer is made from barley: First, barley is pressed and gently heated so its starches break down into simple two-sugar units; then yeasts convert these units into ethanol. Payen found that the initial breakdown requires a chemical factor that is not alive and that does not seem to be used up during the process-a catalyst. He called this first enzyme diastase (we call it amylase today).
 
Did this catalyst operate at a distance, increasing the reaction rate all around it, much as raising the temperature of nearby molecules might do? Or did it use physical contact, actually attaching to the molecules whose reaction it catalyzed (its "substrate")?
 
The answer was discovered in 1903 by French chemist Victor Henri. He saw that the hypothesis that an enzyme physically binds to its substrate makes a clear and testable prediction: In a solution of substrate and enzyme, there must be a maximum reaction rate. When all the enzyme molecules are working full tilt, the reaction simply cannot go any faster, no matter how much more substrate you add to the solution. To test this prediction. Henri carried out the experiment whose results you see in the graph, measuring the reaction rate (V) of diastase at different substrate concentrations (S).
 
Analysis
1. Making Inferences As S increases, does V increase? If so, in what manner-steadily, or by smaller and smaller amounts? Is there a maximum reaction rate?
2. Drawing Conclusions Does this result provide support for the hypothesis that an enzyme binds physically to its substrate? Explain. If the hypothesis were incorrect, what would you expect the graph to look like?
3. Further Analysis If the smaller amounts by which V increases are strictly the result of fewer unoccupied enzymes being available at higher values of S, then the curve in Henri's experiment should show a pure exponential decline in V-mathematically, meaning a reciprocal plot (1/V versus 1/S) should be a straight line. If some other factor is also at work that reacts differently to substrate concentration, then the reciprocal plot would curve upward or downward. Fill in the reciprocal values in the table to the right, and then plot the values on the lower graph (1/S on the x axis and 1/V on the y axis). Is a reciprocal plot of Henri's data a straight line?