Final answer:
Induced fit implies the enzyme actively adapts its active site shape for optimal binding of the substrate, leading to a conformational change not consistent with the enzyme structure remaining unchanged or the binding of multiple substrates simultaneously.
Step-by-step explanation:
The concept of induced fit in enzyme action implies that the enzyme's active site is not a rigid structure, but rather flexible, adapting its shape to bind the substrate optimally for catalysis. Once the substrate binds, the enzyme undergoes a conformational change to stabilize the substrate in the transition state, thereby enhancing the reaction rate.
The induced fit model contradicts the option that the enzyme structure remains unchanged (A), as it involves dynamic changes to the structure of the enzyme upon substrate binding. It also opposes the idea that multiple substrates can bind simultaneously (D), since the enzyme's active site adapts to a particular substrate to facilitate the reaction.
Additionally, this model has nothing to do with the reaction rate being independent of temperature (C) or the substrate remaining unaltered during catalysis (B), as the substrate is indeed converted to the product(s) during the reaction.