Optimization of detergents for the assay of cathepsins B, L, S, and K

The differential effects of representative, commonly available ionic (SDS), nonionic (Brij 35, Tween 20, and Triton X-100), and zwitterionic (Chaps) d etergents on the catalytic activity and properties of human cathepsins B, L , S, and K were examined. The presence of detergents in the assay buffer af fected the activity of cathepsins to variable extents; Chaps enhanced the a ctivity of all the enzymes while SDS was most detrimental. Tween 20 lowered cathepsin S activity, while it slightly enhanced that of all other catheps ins studied. The presence of detergents in the activation buffer was clearl y beneficial to both cathepsins L and K, possibly by favoring the release o f the enzyme from the walls of the incubation vessel. Overall, the results indicate that Chaps is the optimal detergent for use with this family of en zymes, (C) 2000 Academic Press.