This recombinant CHO Cathepsin Z (CTSZ; UniProt Q9EPP7) is expressed in CHO cells with a 6xHIS tag and purified to >95% purity. Under reducing conditions, CTSZ appears at ~37 kDa and is quantified by A280. Cathepsin Z is a lysosomal cysteine protease with both carboxypeptidase and non‑proteolytic functions, including roles in immune regulation and cell adhesion. As a CHO‑derived impurity, CTSZ may degrade therapeutic proteins or alter product quality if not effectively removed. This high‑quality recombinant antigen provides a consistent standard for ELISA calibration, antibody development, and HCP profiling. Its CHO origin ensures biological relevance for impurity studies and purification refinement. Ideal for teams evaluating protease activity, monitoring CTSZ‑related risks, or enhancing downstream control strategies.