Determination of Cathepsin S Abundance and Activity in Human Plasma and Implications for Clinical Investigation

J.M. Cox, et al., 430(2), 130-137, Analytical Biochemistry, 2012

To investigate the role of cathepsin S in disease pathogenesis and progression, a sandwich ELISA assay was developed to measure circulating levels in human serum or plasma. An LC-MS method was also developed to help correlate circulating levels with activity of cathepsin S in plasma. Only a small fraction of circulating cathepsin S was found to be active, and attenuated activity correlated with increased association with cystatin C, an endogeneous inhibitor of cathepsin. The Octet QK system was used to determine relative affinity rankings of cathepsin S antibodies to be used for ELISA assay development.

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