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Purification and characterization of elastase-specific inhibitor. Sequence homology with mucus proteinase inhibitor
1Department of Biochemistry, Edinburgh University Medical School.
Abstract:
Elastase-specific inhibitor (ESI) was purified from sputum of patients with chronic bronchitis and compared with mucus proteinase inhibitor (MPI, BrI) isolated, without the use of affinity chromatography on an enzyme, from non-purulent sputum of a patient with bronchial carcinoma. The N-terminal sequence of 27 residues of the latter was determined and showed serine as the only N-terminus. The partial N-terminal amino-acid sequence of ESI shows some homology with MPI, especially around the reactive site of MPI for human neutrophil elastase. This region could therefore be the reactive site of ESI. The thermodynamic and kinetic constants of the reactions of ESI with human neutrophil elastase and with porcine pancreatic elastase show that ESI is a fast-acting inhibitor.
Insights
This study isolated and characterized an elastase-specific inhibitor (ESI) from chronic bronchitis sputum. ESI demonstrates fast-acting inhibition against human neutrophil elastase, suggesting a potential therapeutic role.
Area of Science:
- Biochemistry
- Protease Inhibitors
- Respiratory Medicine
Background:
- Chronic bronchitis is associated with increased protease activity.
- Mucus proteinase inhibitor (MPI) is a known inhibitor of proteases.
- Elastase-specific inhibitor (ESI) is a novel protease inhibitor found in sputum.
Purpose of the Study:
- To purify and characterize ESI from chronic bronchitis sputum.
- To compare ESI with MPI (BrI).
- To investigate the inhibitory mechanism and kinetics of ESI against elastases.
Main Methods:
- Purification of ESI from sputum using non-affinity chromatography.
- N-terminal amino acid sequencing of ESI and MPI.
- Determination of thermodynamic and kinetic constants for ESI-elastase interactions.
Main Results:
- ESI was successfully purified from chronic bronchitis sputum.
- Partial N-terminal sequence of ESI showed homology with MPI, particularly around the reactive site for human neutrophil elastase.
- ESI was identified as a fast-acting inhibitor of both human neutrophil elastase and porcine pancreatic elastase.
Conclusions:
- The region of homology suggests a potential reactive site for ESI.
- ESI acts as a potent and rapid inhibitor of elastases.
- ESI may play a significant role in regulating protease activity in chronic bronchitis.