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.
Department of Clinical Biochemistry, University Hospital, University of Western Ontario, London, Ontario, Canada.
J A
JA
Stark
A R
AR
Henderson
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