| Assay Method Information | |
| | Biological Assay |
| Description: | The recombinant cathepsin K can be expressed in a variety of commercially available expression systems including E coli, Pichia and Baculovirus systems. The purified enzyme is activated by removal of the prosequence by conventional methods.Standard assay conditions for the determination of kinetic constants used a fluorogenic peptide substrate, typically H-D-Ala-Leu-Lys-AMC, and were determined in either 100 mM Mes/Tris, pH 7.0 containing 1 mM EDTA and 10 mM 2-mercaptoethanol or 100 mMNa phosphate, imM EDTA, 0.1% PEG4000 pH 6.5 or 100 mM Na acetate, pH 5.5 containing 5 mM EDTA and 20 mM cysteine, in each case optionally with 1M DTT as stabiliser. The enzyme concentration used was 5 nM. The stock substrate solution was prepared at 10 mM in DMSO. Screens were carried out at a fixed substrate concentration of 60 μM and detailed kinetic studies with doubling dilutions of substrate from 250 μM. The total DMSO concentration in the assay was kept below 3%. All assays were conducted at ambient temperature. Product fluorescence (excitation at 390 nm, emission at 460 nm) was monitored with a Labsystems Fluoroskan Ascent fluorescent plate reader. Product progress curves were generated over 15 minutes following generation of AMC product. |
| Affinity data for this assay | |
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