(a) In the space below draw a free energy landscape diagram for the conversion of substrate (S) into product (P) based on simple transition state theory. Next, using a dashed line, draw indicate the effect of a catalytic enzyme on the diagram. On your diagram include labels for AG for AG*. (b) Transition state analogs - molecules whose structure resembles the transition state for a particular reaction - can often serve as potent competitive inhibitors of enzyme function. Explain why transition state analogs are such potent inhibitors?

Why Do Anabolic and Catabolic Pathways Differ? Why is the pathway for the biosynthesis of a biomolecule at least partially different from the pathway for its catabolism? Why is the pathway for the biosynthesis of a biomolecule inherently more complex than the pathway for its degradation?

Based on your knowledge of the structure of NAD+ and an assumption that coenzyme dissociation is the rate limiting step of the alcohol dehydrogenase mechanism, hypothesize why a N249W mutation at the coenzyme binding site would increase the rate of catalysis.

In an enzymatic reaction: a. the enzyme leaves the reaction chemically unchanged. b. if the enzyme molecules approach maximal rate, and the substrate is continually increased, the rate of the reaction does not reach saturation. c. in the stomach, enzymes would have an optimal activity at a neutral pH. d. increasing temperature above the optimal value slows the reaction rate. e. the least important level of organization for an enzyme is its tertiary structure.

Which of the following statements about inhibition is true? a. Allosteric inhibitors and allosteric activators are competitive for a given enzyme. b. If an inhibitor binds the active site, it is considered noncompetitive. c. If an inhibitor binds to a site other than the active site, this competitive inhibition. d. A noncompetitive inhibitor is believed to change the shape of the enzyme, making its active site inoperable. e. Competitive inhibition is usually not reversible.

Distinguishing the Mechanisms of Class I and Class I Aldolases Fructose bisphosphate aldolase in animal muscle is a class 1 aldolase, which forms a Schiff base intermediate between substrate (for example. fructose-1, 6-bisphosphate or dihydroxyacetone phosphate) and a lysine at the active site (see Figure I8.12). The chemical evidence for this intermediate conies from studies with aldolase and the reducing agent sodium borohydride, NaBH4. Incubation of the enzyme with dihydroxyacetone phosphate and NaBH4 inactivates the enzyme. Interestingly, no inactivation is observed if NabH4 is added to the enzyme in the absence of substrate. Write a mechanism that explains these observations and provides evidence for the formation of a Schiff base intermediate in the aldolase reaction.

The Reactions and Meehanisms of the Leloir Pathway Write the reactions that permit galactose to be utilized in glycolysis. Write a suitable mechanism, tor one of these reactions.

PREDICT In the following reaction series, which enzyme(s) is/are most likely to have an allosteric site to which the end product E binds? (a) enzyme 1 (b) enzyme 2 (c) enzyme 3 (d) enzyme 4 (e) enzymes 3 and 4

The Catabolism of Uric Acid Write a balanced equation for the oxidation of uric acid to glyoxylic acid, CO2, and NH3, showing each step in the process and naming all of the enzymes involved.

Both prokaryotic and eukaryotic organisms carry out some form of glycolysis. How does ha fact support or not support the assertion that glycolysis is one of the oldest metabolic pathways?