A SENSITIVE FLUORESCENT ASSAY FOR MEASURING THE CYSTEINE PROTEASE ACTIVITY OF DER P 1, A MAJOR ALLERGEN FROM THE DUST-MITE DERMATOPHAGOIDES-PTERONYSSINUS

The potent allergenicity of Der p 1, a major allergen of the house dus t Illite Dermatophagoides pteronyssinus, is thought to be related to i ts cysteine protease activity. Therefore, there is considerable intere st in developing a sensitive assay for measuring Der p 1 activity to s creen for specific inhibitors. This study demonstrates for the first t ime that the activity of Der p 1 can be measured conveniently in a con tinuous rate assay with the fluorogenic substrate Boc-Gln-Ala-Arg-AMC (K-m = 280 mu M and k(cat)/K-m = 4.6 x 10(3)/M/s).