Constitutive proteasomal chymotrypsin-like activity.

Untreated B-CLL cells (dark columns) and PBL (light columns) were incubated with the fluorogenic substrate N-suc-L-leu-L-leu-L-val-L-tyr-AMC (100 μmol/L), and AMC fluorescence was measured in a spectrofluorometer (excitation wavelength, 380 nm; emission wavelength, 460 nm). The figure represents assays on cells from 20 patients and 20 normal donors. Error bars indicate the standard deviation.