title: Serum catalase: reversibly formed charge isoform of erythrocyte catalase.
abstract: The different electrophoretic mobilities of erythrocyte and serum catalase (EC 1.11.1.6) were confirmed and the causes responsible for their differences were examined. The presence of a catalase-binding protein in serum that could form a complex with erythrocyte catalase was excluded by incubating serum proteins with erythrocyte catalase. No new unequivocal catalase bands representing a catalase-binding protein were detected. The erythrocyte and serum catalase proved to be charge isoforms: their molecular masses, estimated by gel permeation chromatography or polyacrylamide gel electrophoresis in a nondenaturing system, were very similar, whereas their electrophoretic mobilities were different. Assay of serum catalase by gel permeation and hydrophobic chromatography yielded a product with the same electrophoretic mobility as that of erythrocyte catalase. Different dilution of erythrocyte catalase with human sera led to a gradual decrease of its mobility, 20-fold or greater dilution yielding the same results as for serum catalase. Similarly, when serum catalase was diluted 20-fold or more with 60 mmol/L phosphate buffer, it migrated similarly to erythrocyte catalase. I detected no effect of dialyzable serum ligands, NADPH, or protection of SH groups on the electrophoretic mobility of either catalase isoform. I conclude that formation of charge isoforms of catalase is caused by a reversible, conformational modification due to matrix effect of serum.
authors.affiliation: Department of Laboratory, Municipal Hospital, Sümeg, Hungary.
authors.forename: L
authors.initials: L
authors.lastname: Góth
mesh_terms: D002352:Carrier Proteins / Q000097:blood; D002374:Catalase / Q000097:blood* / Q000737:chemistry; D002845:Chromatography; D002850:Chromatography, Gel; D004563:Electrochemistry; D004588:Electrophoresis, Cellulose Acetate; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D008970:Molecular Weight
chemical_list: D002352:Carrier Proteins; D002374:Catalase