Final answer:
The statement in question is true; binding of an allosteric inhibitor or activator to an enzyme's allosteric site can induce a conformational change that affects the enzyme's catalytic efficiency either negatively or positively, respectively.
Step-by-step explanation:
The statement, "If an enzyme's allosteric (regulatory) binding site is occupied, the enzyme may adopt an alternative conformation that is not optimal for catalysis," is true.
Allosteric enzymes can be regulated by the binding of effector molecules at allosteric sites, which are different from the active site where substrates bind. When an allosteric inhibitor binds to this site, it causes a conformational change affecting the active site.
This change often results in a decrease in the enzyme's ability to catalyze reactions efficiently, known as allosteric inhibition.
Conversely, allosteric activators also bind to allosteric sites but induce a change that increases the enzyme's affinity for the substrate, thereby enhancing the reaction rate.
This regulatory mechanism allows for fine control of enzyme activity and is crucial in metabolic pathways. Therefore, the binding at an allosteric site can either positively or negatively influence an enzyme's activity depending on the nature of the interaction and the regulatory molecule involved.