Cathepsin Assay Kits

Cathepsin Assay Kits are designed to measure the activity of cathepsins, a family of cysteine proteases involved in various cellular processes including protein degradation, antigen processing, and apoptosis. These assays are essential for studying cathepsin functions in health and disease, including cancer, cardiovascular diseases, and neurodegenerative disorders.

Components and Methodology:

1. Cathepsin Substrates:
   • Fluorogenic Substrates: These substrates release a fluorescent signal upon cleavage by active cathepsins. Common fluorogenic substrates include Z-FR-AFC for cathepsin B and Z-RR-AFC for cathepsin L.
   • Colorimetric Substrates: Produce a colorimetric change upon cleavage by cathepsins. Examples include substrates that generate a color change detectable by spectrophotometry.
2. Assay Protocols:
   • Cell Lysates: Cells are lysed to release intracellular components. The lysates are incubated with cathepsin substrates, and the enzyme activity is measured based on substrate cleavage.
   • Tissue Extracts: Tissue samples can be homogenized and used in assays to assess cathepsin activity in specific tissues or organs.
3. Controls and Standards:
   • Positive Controls: Include samples treated with known cathepsin activators or recombinant cathepsins to ensure the assay's performance and accuracy.
   • Negative Controls: Use untreated or inactive samples to confirm the specificity of the assay and detect any background activity.
4. Applications:
   • Disease Research: Investigating the role of cathepsins in diseases such as cancer, cardiovascular diseases, and neurodegenerative disorders. Elevated cathepsin activity is often associated with disease progression and poor prognosis.
   • Drug Discovery: Screening for inhibitors or modulators of cathepsins, which can be potential therapeutic agents for conditions involving dysregulated cathepsin activity.
   • Cellular Processes: Studying the involvement of cathepsins in cellular processes like apoptosis, antigen processing, and extracellular matrix remodeling.
5. Data Analysis:
   • Quantification: The level of cathepsin activity is expressed as relative fluorescence units (RFU) or optical density (OD), with comparisons made between treated and control samples.
   • Normalization: Data is typically normalized to total protein or cell number to account for variations in sample loading and enzyme expression levels.