Bronchial leucocyte proteinase inhibitor (BLPI) is an 11 000 M(r) protein found in human mucous secretions. This inhibitor apparently controls the serine proteinases elastase and cathepsin G, released from extravascular polymorphonuclear leucocytes. A simple, single-step chromatographic procedure for the isolation of BLPI based on its affinity for chymotrypsin was developed. The purified inhibitor was homogeneous by electrophoresis and gel filtration. Amino acid analyses were in close agreement with previous reports, and showed BLPI to be rich in proline and cystine, but lacking histidine. We have further characterized the role of BLPI with respect to human leucocyte elastase and cathepsin G by close examination of the kinetic parameters. Additionally, we have determined the kinetics of association (k(on)) and dissociation (k(off)) for BLPI with bovine trypsin and chymotrypsin. Equilibrium dissociation constants (K(i)) of 1.87 x 10-10M, 4.18 x 10-9M, 8.28 x 10-9M and 2.63 x 10-8M were obtained from human leucocyte elastase, cathepsin G, bovine trypsin and chymotrypsin, respectively. These results discussed with respect to BLPI's possible function in vivo and in its role relative to other inhibitors in bronchial secretions.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:etsu-works-14228 |
| Date | 01 January 1985 |
| Creators | Smith, C. E., Johnson, D. A. |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | ETSU Faculty Works |
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