Purity >85%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie? Blue Staining. MW (observed): 34 kDa & 15-18 kDa, reducing conditions. MW (theoretical): 28 kDa & 16 kDa. The Recombinant Human Kallikrein 2 Protein from R&D Systems is derived from NS0. The Recombinant Human Kallikrein 2 Protein has been validated for the following applications: Enzyme Activity.