Lyophilized. Lyophilized from 2 mM sodium phosphate buffer, pH 6.5. Cathepsin D from human liver. Cathepsin D is a major lysosomal aspartyl protease in mammalian cells produced as a 52 kDa proenzyme. Overexpression of cathepsin D in human breast cancers is associated with higher risk of relapse and metastasis. Cathepsin D degrades extracellular matrix and releases growth factors bound to the matrix. Specific activity: ≥300 units/mg protein. One unit is defined as the amount of enzyme that will digest acid-denatured hemoglobin in 60 minutes, at 37°C, pH 3.3, releasing peptides soluble in 10% TCA, as measured by an increase in absorbance of 1.0 at 280 nm Purity: ≥90% by SDS-PAGE. Soluble in sterile H₂O or Aqueous Buffers. Prepared from tissue of individuals that have been shown by certified tests to be negative for HBsAg and for antibodies to HIV and HCV. EC 3.4.23.5, CAS 9025-26-7, M.W. 42,000.