19F labeled Unnatural amino acids provided a mechanism for protein specific and site-specific isotope labeling in bacterial cells. Here, 19F-trifluoromethyl- phenylalanine was incorporated to different sites of diacylglycerol kinase for further in situ NMR analysis, without protein purification. Differences of 19F chemical shift and T1 relaxation values of 19F-tfmF-DAGK in native E. coli membrane versus in detergent micelles were observed, indicating strong influences of hydrophobic environment to membrane proteins. 19F-Tyrosine was incorporated to E. coli tyrosine kinase and acquired 19F NMR signals illustrate small portion of phosphorylation of the kinase, in the presence of ATP and Mg2+ ions.