Select Starting Materials

Starting materials that can be substituted in a pathway are encircled by a gray frame. You can select the starting materials you wish to substitute by clicking on the corresponding frames in the pathway. You may select one, some, or all of the framed compounds. 

The frames of the selected compounds will be highlighted in blue. To deselect a compound, click on the blue frame, or click on 'Discard Changes' to remove any modifications you have made.