Synthesis of ophthalmic acid in liver and kidney in vivo.

The synthesis of ophthalmic acid, an analogue of glutathione, was studied in vivo in mouse liver and kidney after administration of either L-alpha-aminobutyrate or L-gamma-glutamyl-L-alpha-aminobutyrate as precursor. L-alpha-aminobutyrate accumulated to a much greater extent, and induced a much greater synthesis of ophthalmic acid in the liver than in the kidney. In contrast, L-gamma-glutamyl-L-alpha-aminobutyrate initiated a large and more rapid synthesis of ophthalmic acid in the kidney than in the liver. Experiments with L-gamma-[G(-14)C]glutamyl-L-alpha-aminobutyrate showed that, although part of the dipeptide is degraded to its constituent amino acids, a significant proportion is directly incorporated into kidney ophthalmic acid. In contrast L-gamma-glutamyl-L-alpha-aminobutyrate serves poorly as a direct precursor of liver ophthalmic acid. The present results show that kidney gamma-glutamyl tripeptide synthesis can proceed directly from an exogenous gamma-glutamyl dipeptide precursor.     

Incorporation and intraparticulate hydrolysis of 131 I-albumin by liver and kidney of an amphibian (Bufo arenarum)

After a single injection of formaldehyde-treated 131 I-albumin into the heart, the incorporation of the labelled protein by liver (% of total injected radioactivity/% of body weight of the organ) was far greater than in other organs. In kidney and spleen it was respectively six and three times greater than in lungs, intestine, testis and fatty body. No radioactivity was found in brain. The radioactivity in liver and kidney reached a peak 30 minutes after the injection, and quickly decreased during the following four hours. In the 27,000 g × ten minute particles recovered from liver homogenates of animals sacrificed at various times after injection, the rate of 131 I-albumin hydrolysis in vitro and the percentage of trichloroacetic acid soluble radioactivity at zero time of incubation showed different stages of intraparticulate hydrolytic activity. The incorporation and intraparticulate hydrolysis in toad kidney was very low if compared with that of toad liver or mouse kidney; however the catheptic specific activity in toad kidney doubles that of mouse kidney. Isolated toad liver was perfused with total blood, containing 131 I-albumin, for five hours at 22°C in a special chamber. In this conditions, 16% of the labelled albumin was hydrolyzed by the liver.     

Effects of ischaemia on content of metabolites in rat liver and kidney in vivo

1. The time-course of changes in content of intermediates of glycolysis in rat liver and kidney cortex after severance of blood supply was investigated. 2. The decline in content of ATP was more rapid in kidney (1.7-0.5mumol/g in 30s) than in liver (2.7-1.6mumol/g in 60s). In both tissues AMP and P(i) accumulated. 3. Net formation of lactate was 1.7mumol/g during the second minute of ischaemia in liver from well-fed rats, 1.1mumol/g in liver from 48h-starved rats, and about 1.0mumol/g during the first 30s of ischaemia in kidney. Net formation of alpha-glycerophosphate was rapid, especially in liver. 4. In kidney the concentration of beta-hydroxybutyrate rose, but that of alpha-oxoglutarate and acetoacetate decreased. 5. In both organs the concentrations of fructose diphosphate and triose phosphates increased during ischaemia and those of other phosphorylated C(3) intermediates decreased. 6. The concentration of the hexose 6-phosphates rose rapidly during the first minute of ischaemia in liver, but decreased during renal ischaemia. 7. In kidney the content of glutamine fell after 2min of ischaemia, and that of ammonia and glutamate rose. 8. The redox states of the cytoplasmic and mitochondrial NAD couple in kidney cortex were similar to those in liver. 9. The regulatory role of glycogen phosphorylase, pyruvate kinase and phosphofructokinase is discussed in relation to the observed changes in the concentrations of the glycolytic intermediates.     

The synthesis and degradation of rat liver and kidney fructose bisphosphatase in vivo.

Sedoheptulose 1,7-bisphosphate has been shown to be present in extracts of normal rat liver. Its concentration in this tissue, estimated by colorimetric and enzymatic assays, is in the range of 5–7 nmol/g tissue. The concentration of sedoheptulose 7-phosphate in these extracts was 110 nmol/g tissue. Also present were mono- and bisphosphate esters of d-glycero-d-ido-octulose and d-glycero-d-altro-octulose, in concentrations ranging from 1–10 nmol/g tissue. Sedoheptulose 1,7-bisphosphate may function as a reservoir for erythrose 4-phosphate. The possible origin of the eight-carbon sugars and their function are discussed.     

Metabolism of gamma-glutamyl amino acids and peptides in mouse liver and kidney in vivo.

The metabolism in vivo of gamma-glutamyl amino acids and peptides was studied in the mouse after administration of loading doses of L-gamma-glutamyl-2-aminobutyrate and several other gamma-glutamyl compounds, including glutathione. A great and rapid accumulation of glutamate, glutamine, aspartate and pyrrolidone carboxylate was observed in the kidney. Similarly, after administration of a tracer dose of L-gamma-[14C]glutamyl-L-2-aminobutyrate a rapid incorporation of label into kidney glutamate, glutamine and aspartate was found. These results suggest that both the hydrolytic and gamma-glutamyl transfer reactions catalyzed by gamma-glutamyl transpeptidase are active in the renal handling of gamma-glutamyl compounds. Indirect evidence was obtained that L-gamma-glutamyl-2-aminobutyrate is partially taken up by the kidney cell in an intact form. In contrast to the kidney, administration of several gamma-glutamyl derivatives did not cause an increase in liver glutamate, glutamine and pyrrolidone carboxylate. After administration of L-gamma-glutamyl-2-aminobutyrate only a slight increase in liver aspartate and pyrrolidone carboxylate was observed. Experiments with L-gamma-[14C]glutamyl-L-2-aminobutyrate suggest that this derivative is largely first degraded to its component amino acids (probably in the kidney) before entering into the metabolism of the liver cell. gamma-Glutamyl transpeptidase may function in the metabolism and transport of glutathione and other gamma-glutamyl compounds in a manner analogous to the function of dipeptidases and disaccharidases in the metabolism and transport of dipeptides and disaccharides respectively.     

Degradation of 2-chlorobenzoate by in vivo constructed hybrid pseudomonads

Abstract 5-Chlorosalicylate degrading bacteria were obtained from the mating between Pseudomonas sp. strain WR401 and Pseudomonas sp. strain B13. Further selection of the hybrid organisms for growth on 2-chlorobenzoate allowed the isolation of strains such as JH230. During growth on 2-chlorobenzoate stoichiometric amounts of chloride were released. Steps in the pathway for 2-chlorobenzoate degradation were determined by simultaneous adaptation studies, assays of enzymes in cell extracts and cooxidation of the analogous substrate 2-methylbenzoate. Results indicate that 2-chlorobenzoate was degraded to 3-chlorocatechol. Ring cleavage of 3-chlorocatechol was by a catechol 1,2-dioxygenase to from 2-chloro- cis, cis - muconate. Further degradation runs via 4-carboxymethylenebut-2-en-4-olide.     

Degradation of 3-chlorobiphenyl by in vivo constructed hybrid pseudomonads

Abstract 3-Chlorobiphenyl-degrading bacteria were obtained from the mating between Pseudomonas putida strain BN10 and Pseudomonas sp. strain B13. Strains such as BN210 resulted from the transfer of the genes coding the enzyme sequence for the degradation of chlorocatechols from B13 into BN10, whereas B13 derivatives such as B131 have acquired the biphenyl degradation sequence from BN10. During growth of the hybrid strains on 3-chlorobiphenyl 90% chloride was released. Activities of phenylcatechol 2,3-dioxygenase, benzoate dioxygenase, catechol 1,2-dioxygenase, chloromuconate cyloisomerase and 4-carboxymethyl-enebut-2-en-4-olide hydrolase were found in 3-chlorobiphenyl-grown cells. The hybrid strains were found to convert some congeners of the Aroclor 1221 mixture such as mono- and dichloro-substituted biphenyls.