Enzymes that catalyze endergonic reactions are likely to bind to ATP.
Endergonic reactions require an input of energy to proceed, and ATP (adenosine triphosphate) serves as a primary energy currency in cells. When enzymes catalyze these reactions, they often facilitate the transfer of a phosphate group from ATP, thereby harnessing and utilizing the energy stored in ATP to drive the endergonic process.
Binding to phosphate or ADP may also be relevant in certain contexts (for example, in the case of ATP hydrolysis releasing energy), but the primary association for catalyzing endergonic reactions is through ATP. Binding to each other is typically not a characteristic feature specific to endergonic reactions.