Induced transitions play a key role in many cellular processes, both as mechanisms of specific ligand binding as well as mediators of energy transduction. Transitions induced by ligands are understood to be processes in which intrinsic binding energy is used topay foran energetically-unfavorable conformational change. The transition pathway is commonly represented as a two-step reaction in which ligand attachment to the protein “causes” it to change conformation. Here we seek a better understanding of induced transitions by looking at how binding energy is usedduringan induced transition. We focus on the allosteric protein globule itself and look at changes in globule structure and energy from both classical biochemical as well as physical points of view. We consider both the sequenceandtime dependence of changes in globule structure and energy. We find that ligand-induced transitions may be regarded as two-step processes of energy transformation: In the first step, the presence of steric misfit leads to the input of potential energy to the system and the conversion of binding energy into a driving force for globule rearrangement. Presence of an activation energy barrier hindering rearrangement leads to storage of this energy in the globule. In the second step, fulfillment of latent bonding interactions and relaxation to the high-affinity conformation leads to output of the stored energy via dissipation and, in the case of transducing proteins, external work. ©1999 American Institute of Physics.