Role of carbohydrate moieties in peanut (Arachis hypogaea) peroxidases.
The activities of a cationic (C.PRX) and an anionic peroxidase isolated from peanut (Arachis hypogaea)-cell suspension culture were drastically reduced when they were deglycosylated with glycopeptidase F or oxidized by 10 mM-periodate. In contrast with the controls, the deglycosylated or the oxidized peroxidases were much more susceptible to proteolytic degradation. In radiolabelling experiments with [35S]methionine, the non-glycosylated C.PRX was synthesized in the tunicamycin-treated cultures and secreted into the medium. Examination of the C.PRX polypeptides by SDS/polyacrylamide-gel electrophoresis followed by fluorography showed that the non-glycosylated form had an Mr of approx. 31,000, which is about 78% of that of the glycosylated form. Our results suggest that carbohydrates may not be essential for peroxidase secretion, but that stabilization of the peroxidase molecules and acquisition by these isoenzymes of a catalytically active conformation is linked directly or indirectly to glycosylation.
Hu
C F
CF
Department of Plant Sciences, University of Western Ontario, London, Canada.
van Huystee
R B
RB
D010367:Arachis / Q000187:drug effects / Q000201:enzymology*; D015153:Blotting, Western; D050260:Carbohydrate Metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D007527:Isoenzymes / Q000378:metabolism*; D010544:Peroxidases / Q000378:metabolism*; D011233:Precipitin Tests; D013050:Spectrometry, Fluorescence; D014415:Tunicamycin / Q000494:pharmacology
D007527:Isoenzymes; D014415:Tunicamycin; D010544:Peroxidases