Utilizing the quantum mechanical consistent force field (QCFF/PI) along with the semimacroscopic protein dipole-Langevin dipole (PDLD/S) method, combined with the linear response approximation (LRA), our findings affirm the significance of the phenolate and pyrazine states of coelenteramide in RLuc8 and its D162A mutant. These states, resulting from proton transfers of neutral emitter to D162 and the presence of counter ion respectively, are pivotal for consistent bioluminescence emission energy. Notably, our computed emission wavelength for the amide ion in D120A, matches closely with experimental results. Additionally, our approach offers a robust mechanism for integrating the energetics of the proton transfer in bioluminescence reactions. This is done by determining the free energy of the reaction landscape by assessing the p𝐾 𝑎 differences of the donor-acceptor proton transfer (PT) process in both the excited and ground states using the PDLD/S-LRA method (see section 2.2 and 3). This deprotonation energy is then added to the emission spectra derived from the QCFF/PI (see section 2.1). This combined approach proves to be the most effective in studying the bioluminescence process that involve proton transfer.