Chymotrypsin. Peptide arrays were incubated for 30 min at room temperature with 0.1 g/L bovine Chymotrypsin (Sigma C4129) dissolved in 0.1 M Tris/Acetate pH 8.0. After washing in the same buffer containing 0.1% SDS, the slides were washed with deionized water and air-dried. Staining of amino groups exposed by enzyme cleavage was made by incubation of the slides for 10 min in 1 mM 5(6)-TAMRA (carboxytetramethylrhodamine, Fluka 21953) activated with 1 eq HBTU, 2 eq DIEA in nmethylpyrrolidone.