title: Inhibition of mast cell chymase by eglin c and antileukoprotease (HUSI-I). Indications for potential biological functions of these inhibitors.
abstract: Recombinant eglin c (originally isolated from the medical leech) and antileukoprotease (HUSI-I from human seminal plasma) were examined for their ability to inhibit the mastcell protease chymase. Both inhibitors react rapidly with the enzyme: when about equimolar concentrations (in the range of 10(-8) M) of chymase and HUSI-I or eglin c were incubated the complex formation was apparently at equilibrium after 1 or 5 min respectively. When a constant amount of chymase (approximately 3 X 10(-8) M) was incubated with increasing concentrations of inhibitor a concentration of HUSI-I of 7 X 10(-7) M was necessary to cause 50% inhibition of the initial enzyme activity, whereas 8 X 10(-8) M eglin c was sufficient. The dissociation constant of the chymase-eglin c complex was calculated to be 4.4 X 10(-8) M. These results are discussed with respect to the possible in vivo function of antileukoprotease as an inhibitor of mast cell chymase.
mesh_terms: D000818:Animals; D053818:Chymases; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D010450:Endopeptidases; D008168:Lung / Q000166:cytology; D008407:Mast Cells / Q000187:drug effects / Q000201:enzymology*; D011480:Protease Inhibitors / Q000494:pharmacology* / Q000502:physiology / Q000627:therapeutic use; D011485:Protein Binding; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins / Q000494:pharmacology* / Q000502:physiology / Q000627:therapeutic use; D011994:Recombinant Proteins / Q000494:pharmacology* / Q000502:physiology / Q000627:therapeutic use; D012697:Serine Endopeptidases; D015843:Serpins; D013552:Swine
chemical_list: D011480:Protease Inhibitors; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D011994:Recombinant Proteins; D015843:Serpins; C028656:eglin proteinase inhibitors; D010450:Endopeptidases; D012697:Serine Endopeptidases; D053818:Chymases