In situ heterogeneity of peroxisomal oxidase activities: An update

Abstract

Oxidases are a widespread group of enzymes. They are present in numerous organisms and organs and in various tissues, cells, and subcellular compartments, such as mitochondria. An important source of oxidases, which is investigated and discussed in this study, are the (micro)peroxisomes. Oxidases share the ability to reduce molecular oxygen during oxidation of their substrate, yielding an oxidized product and hydrogen peroxide. Besides the hydrogen peroxide-catabolizing enzyme catalase, peroxisomes contain one or more hydrogen peroxide-generating oxidases, which participate in different metabolic pathways. During the last four decades, various methods have been developed and elaborated for the histochemical localization of the activities of these oxidases. These methods are based either on the reduction of soluble electron acceptors by oxidase activity or on the capture of hydrogen peroxide. Both methods yield a coloured and/or electron dense precipitate. The most reliable technique in peroxisomal oxidase histochemistry is the cerium salt capture method. This method is based on the direct capture of hydrogen peroxide by cerium ions to form a fine crystalline, insoluble, electron dense reaction product, cerium perhydroxide, which can be visualized for light microscopy with diaminobenzidine. With the use of this technique, it became clear that oxidase activities not only vary between different organisms, organs, and tissues, but that heterogeneity also exists between different cells and within cells, i.e. between individual peroxisomes. A literature review, and recent studies performed in our laboratory, show that peroxisomes are highly differentiated organelles with respect to the presence of active enzymes. This study gives an overview of the in situ distribution and heterogeneity of peroxisomal enzyme activities as detected by histochemical assays of the activities of catalase, and the peroxisomal oxidases D-amino acid oxidase, L-alpha-hydroxy acid oxidase, polyamine oxidase and uric acid oxidase.

Physiological and Biochemical Responses of Fern Nephrolepis Biserrata (Sw.) Schott. to Coccus Hesperidum L. Infestation

“…Unlike peroxidase, catalase is localized mainly to the peroxisomes of photosynthetic plant cells, and is the marker enzyme for them. It takes an active part in neutralization of hydrogen peroxide and (primarily) superoxide to water (van Den Munckhof, 1996). The joint effect of catalase and peroxidase helps to ease the effect of ROS in plants invaded by insects.…”

Activation of flavin-containing oxidases underlies light-induced production of H 2 O 2 in mammalian cells

“…Live cells were irradiated in the presence of substrate [(3-amino-9-ethylcarbazole (AEC) or 3,3Ј-diaminobenzidine (DAB)] but without exogenous H 2 O 2 . Reaction product (polymerized substrate) was expected wherever H 2 O 2 was produced in proximity to endogenous catalase, peroxidase, and/or oxidase (28). DAB stock solution (10 mg/ml; Electron Microscopy Sciences, Ft. Washington, PA) was prepared in DMSO (Aldrich) and diluted 1:1,000 in saline for use.…”

Regional and Ultrastructural Immunolocalization of Copper-Zinc Superoxide Dismutase in Rat Central Nervous System

“…However, ultrastructural examination of many different areas of the brain gives strong indication of a particulate CuZnSOD as well. We first interpreted these vescicles as peroxisomes on the basis of their size and morphology; even the dishomogeneous immunostaining observed within these organelles is in keeping with their peroxisomal nature, because a subcompartmentalization of peroxisomal enzymes has been largely demonstrated (for review see Van Den Munckhof 1996). Postembedding double immunogold labeling confirmed that the CuZnSOD-positive particles are true peroxisomes.…”