In vitro effect of elastase and cathepsin G from human neutrophils on creatine kinase and lactate dehydrogenase isoenzymes.
The polymorphonuclear granulocyte, or neutrophil, has been implicated as a mediator of tissue-destructive events because it releases the preformed proteolytic enzymes elastase and cathepsin G, and, as a result of myeloperoxidase action, hypochlorous acid. We show that elastase inactivates and fragments creatine kinase isoenzymes CK-2 and CK-3, and, to a lesser extent, lactate dehydrogenase (LD) isoenzyme LD-1, whereas cathepsin G acts only on CK-2. Both neutrophil enzymes act on LD-3. The course of inactivation was followed by measuring the loss of catalytic activity at 37 degrees C. The evidence for fragmentation was obtained by gel filtration; electrophoresis after sample treatment with sodium dodecyl sulfate and 2-mercaptoethanol was less satisfactory for this purpose. Hypochlorous acid inactivates CK activity by about 75% at concentrations as low as 8 mumol/L and totally at concentrations > 140 mumol/L, whereas LD activity is not affected until concentrations exceed 200 mumol/L. After a myocardial infarction, the number of neutrophils increases; they are triggered and concentrate around damaged myocardial tissue. Our data suggest that neutrophils may inactivate and fragment "cardiac" enzymes released from such damaged tissue.
Stark
J A
JA
Department of Clinical Biochemistry, University Hospital, University of Western Ontario, London, Ontario, Canada.
Henderson
A R
AR
D056649:Cathepsin G; D002403:Cathepsins / Q000378:metabolism / Q000494:pharmacology*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003402:Creatine Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D006997:Hypochlorous Acid / Q000494:pharmacology; D007527:Isoenzymes; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007958:Leukocyte Count; D009504:Neutrophils / Q000201:enzymology*; D010196:Pancreatic Elastase / Q000378:metabolism / Q000494:pharmacology*; D012697:Serine Endopeptidases
D007527:Isoenzymes; D006997:Hypochlorous Acid; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; D010196:Pancreatic Elastase