Browsing by Author "Koenig, C"

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    Oxalate oxidase from Ceriporiopsis subvermispora
    (1999) Aguilar, C; Urzúa, U; Koenig, C; Vicuña, R
    The enzyme oxalate oxidase was identified in mycelial extracts of the basidiomycete Ceriporiopsis subvermispora and thereafter purified to homogeneity. The purification procedure included only three steps: Q-Sepharose chromatography, precipitation at pH 3.0, and phosphocellulose chromatography. The enzyme is a 400-kDa homohexamer, as determined by gel permeation in Sephadex G-200 and SDS-polyacrylamide gel electrophoresis. Isoelectrofocusing revealed a pi of 4.2. Optimal activity was obtained at pH 3.5 and at 45 degrees C. The purified enzyme has K-m and k(cat) values of 0.1 mM and 88 s(-1), respectively. It is highly specific for oxalate, although it is inhibited at concentrations of this substrate above 2.5 mM. Hystochemistry studies conducted over mycelium slices showed reactions products in both endocellular and periplasmic associated elements. A possible connection between the intracellular metabolism of oxalate and the extracellular ligninolytic activity of the fungus is proposed. (C) 1999 Academic Press.
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    Subcellular localization of catalase in sea urchin (Tetrapigus niger) gametes
    (1997) Figueroa, C; Kawada, ME; Munizaga, A; González, S; Barros, C; Koenig, C; Santos, MJ
    Peroxisomes are essential subcellular organelles that appear to be derived from pre existing organelles. To test the presence of peroxisomes in sea urchin (Tetrapigus niger) sperm and eggs, we performed biochemical and morphological experiments to evaluate the subcellular distribution of catalase as the typical peroxisomal marker. In sea urchin sperm, we found that catalase is localized in the cell cytosol. In contrast, sea urchin eggs contain sedimentable catalase, presumably contained in peroxisome-like structures detected by immunomicroscopy and by cytochemistry. Our results show, for the first time, evidence for the presence of peroxisome-like structures in sea urchin eggs and provide evidence for the peroxisome biogenesis hypothesis by division of preexisting organelles. (C) 1997 Elsevier Science Inc.