title: [Intracellular localisation of urea-cycle enzymes in liver (author's transl)].
abstract: Enzymes of the Krebs-Henseleit urea-cycle were localized by means of differential centrifugation and fractional tissue extraction in rat liver and in human liver. Argininosuccinatlyase (ASAL) and Argininosuccinatsynthetase (ASAS) represent enzymes of the soluble cytoplasmic fraction. Ornithine-ketoacid-transaminase(OKT), carbamyl-phosphate-synthetase (CPS) and ornithine-carbamyl-transferase (OCT) are localized in the mitochondrial and nuclei fractions of the liver cell. Most of the arginase activity is bound to subcellular structures (probably to nuclei). A small portion of arginase-activity was found in the soluble cytoplasmatic fraction. The enzymes of the Krebs-Henseleit urea-cycle are equally distributed in rat liver and in human liver. Differences in the subcellular localisation of (mitochondrial) enzymes in human liver could be attributed to mitochondrial breakage during tissue preparation and do not represent in-vivo conditions.
mesh_terms: D000818:Animals; D001119:Arginase / Q000032:analysis; D001123:Argininosuccinate Lyase / Q000032:analysis; D001124:Argininosuccinate Synthase / Q000032:analysis; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000032:analysis; D002467:Cell Nucleus / Q000201:enzymology; D002952:Citric Acid Cycle; D003600:Cytosol / Q000201:enzymology; D005260:Female; D006801:Humans; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D008930:Mitochondria, Liver / Q000201:enzymology; D009954:Ornithine Carbamoyltransferase / Q000032:analysis; D009953:Ornithine-Oxo-Acid Transaminase / Q000032:analysis; D051381:Rats; D013045:Species Specificity; D013347:Subcellular Fractions / Q000201:enzymology; D014508:Urea / Q000096:biosynthesis*
chemical_list: D014508:Urea; D009954:Ornithine Carbamoyltransferase; D009953:Ornithine-Oxo-Acid Transaminase; D001119:Arginase; D001123:Argininosuccinate Lyase; D002222:Carbamoyl-Phosphate Synthase (Ammonia); D001124:Argininosuccinate Synthase
vernacular_title: Intrazelluläre Lokalisation von Enzymen des Krebs-Henseleit-Cyclus in der Leber