TAILIEUCHUNG - Báo cáo khoa học: Oxidized elafin and trappin poorly inhibit the elastolytic activity of neutrophil elastase and proteinase 3

Neutrophil proteinase-mediated lung tissue destruction is prevented by inhibitors, including elafin and its precursor, trappin. We wanted to estab-lish whether neutrophil-derived oxidants might impair the inhibitory func-tion of these molecules. Myeloperoxidase⁄H2O2 and N-chlorosuccinimide oxidation of the inhibitors was checked by mass spectrometry and enzy-matic methods. | ềFEBS Journal Oxidized elafin and trappin poorly inhibit the elastolytic activity of neutrophil elastase and proteinase 3 Shila M. Nobar1 Marie-Louise Zani2 Christian Boudier1 Thierry Moreau2 and Joseph G. Bieth1 1 Laboratoire d Enzymologie INSERM U392 Université Louis Pasteur de Strasbourg Illkirch France 2 INSERM U618 Universite Francois Rabelais Tours France Keywords elafin elastase enzyme kinetics oxidation proteinase 3 Correspondence J. G. Bieth INSERM U 392 Faculte de Pharmacie 74 route du Rhin 67400 Illkirch France Fax 33 3 90 24 43 08 Tel 33 3 90 24 41 82 E-mail jgbieth@ Received 20 May 2005 revised 24 August 2005 accepted 22 September 2005 doi Neutrophil proteinase-mediated lung tissue destruction is prevented by inhibitors including elafin and its precursor trappin. We wanted to establish whether neutrophil-derived oxidants might impair the inhibitory function of these molecules. Myeloperoxidase H2O2 and N-chlorosuccinimide oxidation of the inhibitors was checked by mass spectrometry and enzymatic methods. Oxidation significantly lowers the affinities of the two inhibitors for neutrophil elastase NE and proteinase 3 Pr3 . This decrease in affinity is essentially caused by an increase in the rate of inhibitory complex dissociation. Oxidized elafin and trappin have however reasonable affinities for NE Ki X 10 9 m and for Pr3 Ki X 10 8 m . These affinities are theoretically sufficient to allow the oxidized inhibitors to form tight binding complexes with NE and Pr3 in lung secretions where their physiological concentrations are in the micromolar range. Yet they are unable to efficiently inhibit the elastolytic activity of the two enzymes. At their physiological concentration fully oxidized elafin and trappin do not inhibit more than 30 of an equimolar concentration of NE or Pr3. We conclude that in vivo oxidation of elafin and trappin strongly impairs their activity. Inhibitor-based therapy of

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