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Biochemistry

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Reaction Diagram for an Enzyme

BIOCHM-FOGNEA

Arginosuccinate synthase is an important enzyme in arginine biosynthesis. It catalyzes the reaction that is shown below: in the reaction mechanism, citrulline attacks the phosphate of ATP to make citrulline adenylate.

This molecule then undergoes a nucleophilic attack by the aspartate to produce the product, arginosuccinate. Reaction diagrams are ways to depict the energy and process of a chemical reaction with Gibbs free energy as the y-axis and reaction progress as the x-axis.

If the reaction diagram for this enzyme was shown, it would have which of the following properties?

$$\text{citrulline + aspartate + ATP} \xrightarrow [ ]{ } \text{arginine + AMP + pyrophosphate}$$

A

The reaction diagram would have one transition state and one intermediate.

B

The reaction diagram would have two transition states and one intermediate.

C

The reaction diagram would have one transition state and no intermediates.

D

The reaction would have one intermediate and no transition states.