[Histochemistry of amino acid naphthylamidases]

For the correct intracellular localization of amino acid naphthyl-amidases freeze-dried cryostat sections or aldehyde fixed tissue blocks followed by washing in buffer or sugar solution are suitable. Among various amino acid 2-naphthylamides and diazonium salts L-Leucin-4-methoxynaphthylamide and Fast Blue B "pure" (Serva) respectively can be recommended for the histochemical demonstration of these enzymes. In situ the intestinal and renal brush border represent the only cellular structure which actually contain naphthylamidases. By means of alpha,-L-glutamic acid 2-naphthylamide as substrate the glomerula of the kidney also react indicating that further binding sites must exist for amino acid naphthylamidases.