Bacterial reaction centers (RCs) are the membrane proteins responsible for the initial charge separation steps central to photosynthesis. They capture solar energy in a highly efficient combination of energy and electron transfer steps. RCs possess two branches of chromophores arranged in nearly identical paths, L and M. Following photoexcitation, however, electrons are only transferred down the L branch of chromophores. Despite intense effort, the origin(s) of this unidirectional electron transfer is not fully understood, and even the role of intermediary electron acceptors, is unclear. To better study these issues, we have recently transferred an amber codon suppression system from E. coli into the bacteria needed to produce RCs, R. sphaeroides. Numerous challenges were overcome to implement amber suppression in R. sphaeroides; they further inform on the often-unforeseeable hurdles that can be involved in host transfer of amber suppression from E. coli. With this system in hand, we can more finely dissect the role of key amino acids in a way previously inaccessible to photosynthetic research using non-canonical amino acids. Initial work focuses on the -OH dipole strength in tyrosine M210, believed to play a key role in modulating primary charge separation. This is accomplished by using differently halogenated tyrosine variants (e.g. mono-Cl, -Br and -I) to inspect the gradual effect of these structural changes on RC function. Detailed characterization of RC mutants incorporating these variants will be described. Non-canonical amino acids in the form of site-specific probes are also being pursued. These tools greatly broaden the scope of site-directed mutagenesis in this complex membrane protein. Their additional insight may help us better understand protein design in this model for electron transfer.