title: Inhibition of proteinase-like peptidase activities in serum and tissue from breast cancer patients.
abstract: The inhibitory profiles of several proteinase-like peptidases active on synthetic peptide (MCA) substrates, present in sera and 100,000g supernatants of malignant tissue from patients with breast cancer, have been studied using a series of known inhibitors including epoxysuccinyl peptides (E-64, Ep-475), Z-Phe-Phe-diazomethane, PMSF, iodoacetamide, 1-10-O-phenanthroline, leupeptin, aprotinin, elastatinal and alpha 2-macroglobulin. While in general the inhibition profiles confirmed reported substrate specificities some anomalies were observed. In particular, the serum activities on two cathepsin B substrates were unaffected by specific cysteine proteinase inhibitors and in breast tissue only 20-37% of activity towards these two substrates was apparently due to the presence of endopeptidases. However, the potent inhibition of other proteinase-like activities by the epoxysuccinyl peptides and leupeptin, or similar inhibitors, may be useful agents in the study of methods of combating tumour spread.
mesh_terms: D001943:Breast Neoplasms / Q000097:blood / Q000201:enzymology*; D005260:Female; D006801:Humans; D007700:Kinetics; D010447:Peptide Hydrolases / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology*; D011485:Protein Binding; D013379:Substrate Specificity
chemical_list: D010447:Peptide Hydrolases