Fmoc-Azidohomoalanine, ; MW 366.3; M.F. C19H18N4O4 (100 mg) (AHA) is an azido derivative of homoalanine that functions as a methionine (Met) analog when incorporated into proteins. It is recognized by Met-tRNA synthetase and is used for the translation of AUG codons competitively with Met. AHA-containing proteins/peptides can be enriched and separated from the whole proteome, and can serve as effective IR probes into proteins¿ local electrostatic environments. By replacing Met with AHA in culture media, AHA gets readily incorporated into proteins of cells as seen with zebrafish, C. elegans, tadpoles, brain slices and rodent retina proteins. To quantify tissue proteome of newly synthesized proteins in animal disease models, Pulse AHA Labeling in Mammals (PALM) technique that allows incorporation of AHA into an entire animal¿s proteome is used. In Solid Phase Peptide Synthesis, AHA is used to synthesize modifiable side-chain peptides/proteins.