Pharmacological activity of the C-terminal and N-terminal domains of secretory leukoprotease inhibitor in vitro.
1. In order to characterize the physiological functions of the domain structure of secretory leukoprotease inhibitor (SLPI), the biological capacities of half-length SLPIs, (Ser1-Pro54)SLPI and (Asn55-Ala107)SLPI, were investigated and compared with those of full-length SLPI. 2. The activities of these inhibitors against several serine proteases were determined using synthetic chromogenic substrates. The inhibitory capacity of the C-terminal domain, (Asn55-Ala107)SLPI, was as strong as that of full-length SLPI against human neutrophil elastase (NE), cathepsin G and chymotrypsin. It possessed less trypsin inhibitory activity than intact SLPI. For the N-terminal domain of SLPI, (Ser1-Pro54)SLPI, no inhibitory activity could be detected against the serine proteases tested in this study. 3. The inhibitory activity of (Asn55-Ala107)SLPI against the proteolysis of the natural substrates elastin and collagen by NE was comparable with that of full-SLPI (elastin, IC50 = 907 +/- 31 nM for SLPI, 767 +/- 33 nM for (Asn55-Ala107)SLPI; collagen, IC50 = 862 +/- 36 nM for SLPI, 727 +/- 47 nM for (Asn55-Ala107)SLPI). 4. The binding affinities of full- and half-length SLPIs for heparin were measured by affinity column chromatography. Full-length SLPI showed high affinity for heparin while the binding capacities of both half-length SLPIs were lower. (Concentration of NaCl for elution, 0.45 M for SLPI, 0.24 M for (Ser1-Pro54)SLPI, 0.27 M for (Asn55-Ala107)SLPI). 5. The effects of full-SLPI and (Asn55-Ala107)SLPI on blood coagulation were measured using the activated partial thromboplastin time (APTT). Full-length SLPI prolonged clotting time dose dependently(1.25, 2.5 and 5.0 microM), whereas (Asn55-AlalO7)SLPI had no effect even at the highest concentration.6. In conclusion, the C-terminal domain of SLPI is a promising candidate for the treatment of inflammatory diseases in which participation of neutrophil proteases has been suggested.
Masuda
K
K
Institute for Biomedical Research, Teijin Limited, Tokyo, Japan.
Kamimura
T
T
Watanabe
K
K
Suga
T
T
Kanesaki
M
M
Takeuchi
A
A
Imaizumi
A
A
Suzuki
Y
Y
D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects*; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006801:Humans; D066298:In Vitro Techniques; D007249:Inflammation / Q000097:blood / Q000201:enzymology; D015394:Molecular Structure; D011480:Protease Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D012697:Serine Endopeptidases / Q000187:drug effects*
D011480:Protease Inhibitors; D012697:Serine Endopeptidases