Bke2 Biochemistry Exercises

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Group exercise: Enzymes in glycolysis

The enzyme hexokinase works along the principle of induced fit. Discuss the details of induced fit in this particular enzyme. Why is it important?
How is glycolysis controlled and why is it necessary to control it? What enzyme steps and enzymes are controlled? Why these in particular?
Many intermediates in the pathway are phosphorylated. What is the advantage of having these phosphate groups? What are the enzymes called that put on or take off phosphate groups?
Explain the metabolic role of alcohol dehydrogenase (ADH) in yeasts that are a) fermenting glucose to ethanol and b) aerobically oxidising ethanol.
Inspection of glycolysis reveals that it contains two steps where transfer of a phosphoryl group from ATP occurs (ATP is consumed) and two steps where ATP is formed, yet there is a net gain of two ATP in each cycle. Explain.
The TIM-barrel is a recurring motif in many proteins. What does it look like? It is named after a glycolytic enzyme. Which enzyme, and what reaction is this enzyme the catalyst of?
Phosphofructokinase introduces a second phosphate group into fructose-6-phosphate. Why a second one?
How does a regulatory enzyme work? Use the enzyme phosphofructokinase as an example to explain (or any other example you know well). Do you know any other name for these proteins?
Phosphofructokinase is a multisubunit enzyme. Would it work in the same way if it were a monomeric enzyme?
In order for ATP to serve as a regulator for phosphofructokinase the concentration of ATP has to reach a certain (rather high) level. Why is this? The inhibition of phosphofructokinase by ATP is diminished when the ADP concentration is high How can this observation be explained?

Reading material: Horton, Chapter 12 (Stryer chapter 19)

Lectures:
Carbohydrates, vitamins, glycloysis

Links:
Suggested answers

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