Question

Draw the reaction that is catalyzed by four of the following enzymes:

Phosophoglucomutase

Hexokinase

Acyl CoA dehydrogenase

Carbonic anhydrase

Acetylcholinesterase

Alanine aminotransferase

(b) Choose two of the enzymes. Indicate what metabolic pathway they are part of, if any. Indicate where the enzymes are located. [For example, are they intracellular or extracellular? Are they associated with a particular organelle? Are the bound to a membrane, or free? Are they part of a larger enzyme-complex?] Does the enzyme require a cofactor, such as NAD+ or FAD or ATP or thiamine or pyridoxal?

(c) For one of the enzymes you chose in part (b), indicate whether the enzyme is affected, either positively or negatively, by other molecules.

Answer 1

Hexokinase:
Glucose + ATP -----> Glucose-6-phosphate + ADP

Acyl CoA dehydrogenase:
Acyl CoA + FAD ----> Trans-Δ2-enoyl CoA

Carbonic anhydrase:
CO2 + H2O --------> H2CO3

Acetylcholinesterase:
Acetylcholine + H2O -----> Choline + Acetate

b. Hexokinase
Pathway = Glycolysis
Cellular location = Cytoplasm (Intracellular)
It is a free cytosolic enzyme
It utilizes ATP to phosphorylate glucose

Acyl CoA dehydrogenase:
Pathway = Beta-oxidation
Cellular location = Mitochondrial matrix (Intracellular)
It is a free mitochondrial enzyme
It utilizes FAD as the cofactor

c. Hexokinase catalyzes one of the rate-limiting steps of glycolysis.
It is inhibited by glucose-6-phosphate. It is an example of feedback inhibition that prevents the accumulation of the product