We have been actively pursuing an engineered orthogonal tRNA synthetase pair that would allow us to site specifically incorporate fluorescent dyes (in amino acid form) for the purpose of developing protein based reagentless biosensors to a myriad of small molecules. To this end, I have engineered an orthogonal pair based on the S. cerevisiae tryptophanyl tRNA synthetase and am currently evolving it (using directed evolution techniques) to accept various fluorescent amino acids. Once this work is completed, we plan on incorporating this 'tool' into our ongoing efforts to both design and evolve protein based fluorescent sensors.