title: Localization of catalase A in vacuoles of Saccharomyces cerevisiae: evidence for the vacuolar nature of isolated "yeast peroxisomes".
abstract: The subcellular distribution of catalase A in the yeast Saccharomyces cerevisiae has been investigated. The enzyme was found to be bound to large particles, whereas most of the activity of catalase T was located in a 38 000 X g supernatant. Under various isolation conditions catalase A always showed a distribution among subcellular fractions virtually identical to that of two markers for vacuoles, proteinase B and alpha-mannosidase. More than 80 percent of the catalase A activity of a crude vacuole fraci-onercent of the catalase A activity of a crude vacuole fraction has been detected in purified vacuoles. Malate synthase, isocitrate lyase and glyoxylate reductase (NADP), three peroxisomal markers, showed a subcellular distribution significantly different from that of catalase A. It is concluded from these results that catalase A is specifically associated with the vacuoles of yeast. Like vacuoles, "peroxisomal" fractions isolated from yeast spheroplasts as described by Avers[1] contain only one catalase protein, catalase A. It could be shown by isopycnic and sedimentation velocity separations of crude mitochondrial fractions that catalase A in "peroxisomal" fractions is accompanied by considerable activities of proteinase B and alpha-mannosidase. From all our results it seems that the catalase-active particles isolated under such conditions are not typical peroxisomes but vesicles formed from vacuoles during the isolation procedure.
mesh_terms: D000818:Animals; D002374:Catalase / Q000276:immunology / Q000302:isolation & purification*; D005656:Fungal Proteins / Q000032:analysis; D008830:Microbodies / Q000201:enzymology*; D009940:Organoids / Q000201:enzymology*; D011817:Rabbits / Q000276:immunology; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000648:ultrastructure*; D013104:Spheroplasts / Q000378:metabolism; D014461:Ultracentrifugation
chemical_list: D005656:Fungal Proteins; D002374:Catalase