employing the PDLD/S-LRA method. At a pH of 7, our calculations revealed 11 ionized residues, that are depicted in Figure . Ion pairs within the protein were ionized, while distant residues remained neutral. It is crucial to mention that for the phenolate form of the emitter in RLuc8, the proximate Asp162 residue is presumed to be protonated. This is under the assumption of a proton transfer (PT) between them on the first excited state surface, given that the distance between the oxygen atom of the 6-para hydroxyphenyl group of the emitter and the protonated Asp162 residue is 2.9 Å. This close proximity suggests the likelihood of a PT process and is discussed below.