l-leucine 4-methoxy-β-naphthylamide was identified as a cell-permeable substrate for aminopeptidase m and leucine aminopeptidase that was developed for intracellular analysis of protease activities [1]. in a previous method-developing study, peptide derivatives of 4-methoxy-β-naphthylamine including l-leucine 4-methoxy-β-naphthylamide were incubated in microtiter plates together with nitrosalicylaldehyde. selectivity was achieved by running parallel assays containing inhibitors partially selective for each of peptide derivatives. this method was successfully validated by measurements in cells isolated from cathepsin b-/--, k-/--, and l-/-- mice [2].
[1] monis, b. ,wasserkrug, h. and seligman, a.m. comparison of fixatives and substrates for aminopeptidase. journal of histochemistry and cytochemistry 13(6), 503-509 (1965).
[2] rüttger, a. ,mollenhauer, j.,lser, r., et al. microplate assay for quantitative determination of cathepsin activities in viable cells using derivatives of 4-methoxy-β-naphthylamide. biotechniques 41(4), 469-473 (2006).
