title: Phosphodiesterase II in epithelial cells from guinea-pig and rat small intestine.
abstract: Phosphodiesterase II activity was determined by using a synthetic substrate, the 2,4-dinitrophenyl ester of thymidine 3'-phosphate. The enzyme activity was determined in fractions obtained by differential centrifugation of homogenates of epithelial cells from the small intestinal mucosa of guinea pigs and rats. In guinea-pig preparations phosphodiesterase II occurred with highest specific activity in those fractions rich in succinate dehydrogenase and acid phosphatase. A lysosomal location for the guinea-pig enzyme was indicated by its structure-linked latency and by its association with particles that under-went a characteristic decrease in equilibrium density when Triton WR-1339 was injected into the animals. With rat preparations a much greater proportion of the phosphodiesterase II activity was found in the soluble fraction after ultracentrifugation. The rat enzyme exhibited a lower degree of latency and administration of Triton WR-1339 had no effect. The rat enzyme further differed from that of the guinea pig in other respects; it was more labile at 60 degrees C, it exhibited a lower pH optimum and it had a higher molecular weight as determined by gel-filtration chromatography.
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells; D004848:Epithelium / Q000201:enzymology; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000201:enzymology*; D007421:Intestine, Small / Q000201:enzymology*; D007700:Kinetics; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000494:pharmacology; D051381:Rats; D013045:Species Specificity; D013347:Subcellular Fractions / Q000201:enzymology; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013942:Thymine Nucleotides
chemical_list: D013942:Thymine Nucleotides; D011092:Polyethylene Glycols; D013385:Succinate Dehydrogenase; D000135:Acid Phosphatase; D005952:Glucose-6-Phosphatase; D010727:Phosphoric Diester Hydrolases