Inactivation of α2-Macroglobulin by Activated Human Polymorphonuclear Leukocytes

[摘要] The proteolytic activity of trypsin releases the dye RemazolBrilliant Blue from its high molecular weight substrate, the skinpowder (Hide Powder Azure, Sigma), with an increase in absorbance at595 nm. Active α2- macroglobulin (80 μg/ml) totally inhibits theproteolytic activity of trypsin (14 μg/ml) by trapping thisprotease. But after a 20 min incubation of α2-macroglobulin at 37°Cwith 2 × 106human polymorphonuclear leukocytes activated byN-formyl-L-methionyl-L-leucyl-L-phenylalanine(10−7M) and cytochalasin B (10−8M), 100% of trypsinactivity was recovered, indicating a total inactivation ofα2-macroglobuHn. Incubation with granulocyte myeloperoxidase alsoinactivates α2-macroglobulin. Hypochlorous acid, a by-product ofmyeloperoxidase activity, at a concentration of 10−7M alsoinactivates α2-macroglobulin, which indicates that an importantcause of α2-macroglobulin inactivation by activatedpolymorphonuclear leukocytes could be the activity of myeloperoxidase.

[学科分类] 生理学与病理学