Exercise 9 Return to Index

Introduction

Thus far we have travelled from propane to L-tyrosine, which is the starting point for the journey outlined in Figure 3.1 of Exercise 3. That figure is reproduced here to make sure that we know the route we have to take to get from L-tyrosine to norepinephrine. To arrive at our final destination it will be necessary to learn how to use two more features of the Molecular Editor control panel, the Bond:break and the Model:delete controls.We will also use the Append: tool again, but this time in conjunction with the PubChem option in order to make certain we have arrived at our intended destination.

Figure 3.1 (revisited)

The biosynthetic pathway from tyrosine to norepinephrine

Instructions

1. Replace the H atom on C-3 of the aromatic ring with an OH group.

Welcome to L-dopa!

2. Select the Bond:break option and click on the middle of the C₁-C₂ bond.

This action generates a model of dopamine along with a model of formic acid.

3. Activate the Model:delete option and click on any atom in the formic acid model.

Welcome to dopamine!

4. Replace one of the H atoms of the CH₂ group attached to the aromatic ring with an OH group.

5. Select Append:PubChem and enter norepinephrine in the text box that opens.

6. Compare:compare

Did you arrive in (-)-norepinephrine or its twin city? In either case, we hope you enjoyed the trip. As long as you're here, why not take a look around. In Exercise 10 the VMK provides a guided tour of (-)-norepinephrine.