Yeast fluorophore labeling

An advantage of MPM over techniques based on visible light is that greater resolution can be achieved using fluorescence. Thus fine details and small structural features which have not previously been visualized with other in situ techniques may be revealed. The use of different fluorophores to label different particles also aids identification of the species. A disadvantage of the requirement to label is the need to limit the study to washed yeast cells because fluorophore labeling does affect the filtration performance of unwashed cells, as described in the next section. 

Figure 8.4 The effect of fluorophore labeling and suspension washing of yeast suspensions. A Unwashed fluorophore labeled suspension concentration 0.50gL , A unwashed nonlabeled suspension concentration O.SOgL, washed fluorophore labeled suspension concentration 0.37gL ,...

While it is possible to detect proteins based on the native fluorescence of tryptophan, that amino acid is the least abundant in yeast, representing 1.0% of the total amino acid content of yeast. Excitation of tryptophan requires expensive and temperamental UV lasers. Instead, it is usually more convenient to label the protein with a fluorophore that is excited by inexpensive and reliable lasers that operate in the visible portion of the spectmm. 

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