We developed the PERSIA technique with an interest in quantifying proteins as they are being produced during a cell-free synthesis reaction. A short 6-amino acid sequence added to a protein of interest reacts with a fluorogenic reagent (ReAsH), yielding a measure of protein concentration in close to real time. We combine this measurement with simultaneous fluorescent detection of mRNA production, quantifying both transcription and translation. Alternatively, we combine simultaneous measurement of protein synthesis and that protein's enzymatic activity. We have found these simple capabilities enabling for multiple applications, including sequence-structure-function studies and target-specific assessment of drug candidate compounds.