scholarly journals STUDY ON THE SITE OF BIOSYNTHESIS OF β-GLUCURONIDASE AND ITS APPEARANCE IN LYSOSOME IN NORMAL AND HYPOXIC RATS

1970 ◽  
Vol 18 (8) ◽  
pp. 529-541 ◽  
Author(s):  
JULIEN L. VAN LANCKER ◽  
PATRICK L. LENTZ
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Liver Enzyme ◽  
Rat Liver ◽  
Microsomal Enzymes ◽  
Enzyme Preparations ◽  
Lysosomal Fraction ◽  
Regenerating Rat Liver ◽  
Cell Fractions

For the purpose of investigating the site of synthesis of β-glucuronidase, the enzyme was purified, after injection of labeled amino acids, from various cell fractions of regenerating rat liver. Enzyme preparations purified from microsomal, lysosomal, mitochondrial, nuclear and supernatant fractions had identical catalytic and electrophoretic properties. In nonhypoxic rats, incorporation was detectable only in the microsomal enzymes and maximum labeling occurred 30 min after the injection of the labeled amino acid. No label was detectable in the enzyme purified from the lysosomal fraction of nonhypoxic animals. Labeling of enzyme purified from lysosomal fraction was, however, significant after 2 hr of hypoxia.

The Difference in the Carboxy-Terminal Sequence Is Responsible for the Difference in the Activity of Chicken and Rat Liver Fructose-2,6-Bisphosphatase

2000 ◽  
Vol 381 (12) ◽  
pp. 1195-1202 ◽  
Author(s):  
Zheng Zhu ◽  
Song Ling ◽  
Qi-Heng Yang ◽  
Lin Li
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Liver Enzyme ◽  
Rat Liver ◽  
Amino Acid Sequences ◽  
Kinetic Properties ◽  
Catalytic Core ◽  
Bifunctional Enzymes ◽  
The Difference ◽  
Carboxy Terminal

Abstract The fructose-2,6-bisphosphatase domain of the bifunctional chicken liver enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase shares approximately 95% amino acid sequence homology with that of the rat enzyme. However, these two enzymes are significantly different in their phosphatase activities. In this report, we show that the COOH-terminal 25 amino acids of the two enzymes are responsible for the different enzymatic activities. Although these 25 amino acids are not required for the phosphatase activity, their removal diminishes the differences in the activities between the two enzymes. In addition, two chimeric molecules (one consisting of the catalytic core of the chicken bisphosphatase domain and the rat COOH-terminal 25 amino acids, and the other consisting of most of the intact chicken enzyme and the rat COOH-terminal 25 amino acids) showed the same kinetic properties as the rat enzyme. Furthermore, substitution of the residues Pro456pro457Ala458 of the chicken enzyme with GluAlaGlu, the corresponding sequence in the rat liver enzyme, yields a chicken enzyme that behaves like the rat enzyme. These results demonstrate that the different bisphosphatase activities of the chicken and rat liver bifunctional enzymes can be attributed to the differences in their COOH-terminal amino acid sequences, particularly the three residues.

A SENSITIVE METHOD FOR MEASUREMENT OF AMINO ACYL RIBONUCLEIC ACID SYNTHETASE ACTIVITIES

1962 ◽  
Vol 40 (1) ◽  
pp. 653-666 ◽  
Author(s):  
Murray J. Fraser
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Ehrlich Ascites Carcinoma ◽  
Carcinoma Cells ◽  
Ehrlich Ascites ◽  
Sensitive Method

A sensitive method for the measurement of amino acyl RNA synthetase activities (amino acid activating enzymes) is described. The method is based on measurements of the rates of labelling of soluble ribonucleic acid with14C-amino acids. Determinations of α-glutamyl-RNA, glutaminyl-RNA, and glycyl-RNA synthetase activities in the "pH 5 enzymes" fractions from rat liver and mouse Ehrlich ascites carcinoma cells have been made.

A SENSITIVE METHOD FOR MEASUREMENT OF AMINO ACYL RIBONUCLEIC ACID SYNTHETASE ACTIVITIES

1962 ◽  
Vol 40 (5) ◽  
pp. 653-666 ◽  
Author(s):  
Murray J. Fraser
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Ehrlich Ascites Carcinoma ◽  
Carcinoma Cells ◽  
Ehrlich Ascites ◽  
Sensitive Method

A sensitive method for the measurement of amino acyl RNA synthetase activities (amino acid activating enzymes) is described. The method is based on measurements of the rates of labelling of soluble ribonucleic acid with14C-amino acids. Determinations of α-glutamyl-RNA, glutaminyl-RNA, and glycyl-RNA synthetase activities in the "pH 5 enzymes" fractions from rat liver and mouse Ehrlich ascites carcinoma cells have been made.

scholarly journals Effects of dietary protein or amino acids in the perfusion medium on amino acid metabolism in perfused adult rat liver.

1981 ◽  
Vol 27 (2) ◽  
pp. 149-163 ◽  
Author(s):  
Yoshiaki FUJITA ◽  
Takashi YAMAMOTO ◽  
Toru RIKIMARU ◽  
Hidemichi EBISAWA ◽  
Goro INOUE
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rat Liver ◽  
Dietary Protein ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Perfusion Medium ◽  
Adult Rat

EVIDENCE FOR THE INDUCTION OF URIDINE AND DEOXY-URIDINE PHOSPHORYLASES OF REGENERATING RAT LIVER IN VITRO

1965 ◽  
Vol 43 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Esther W. Yamada
Keyword(s):  
Amino Acids ◽  
Tissue Culture ◽  
Rat Liver ◽  
Culture Medium ◽  
Specific Activity ◽  
Tissue Culture Medium ◽  
Uridine Phosphorylase ◽  
Regenerating Rat Liver ◽  
Specific Activities

Increases in the specific activities of undine and deoxyuridine phosphorylases of slices of regenerating rat liver were found 4 hours after incubation in tissue-culture medium containing uridine or 6-azauridine. These increases were not found when the tissue-culture medium contained either 8-azaguanine or puromycin, or when it lacked amino acids. Although both uridine and 6-azauridine were more effective in increasing the specific activity of uridine phosphorylase than that of deoxyuridine phosphorylase, azauridine was more effective than uridine in increasing the specific activities of both enzymes.In time studies, in which slices of regenerating rat liver were incubated in tissue-culture medium containing optimal concentrations of uridine, the specific activities of the two enzymes reached maximum levels at 3–4 hours. Puromycin prevented these increases.

scholarly journals Inhibitory effect of pH5 enzyme from non-lactating bovine mammary gland on various stages of protein synthesis in the rat liver amino acid-incorporating system

1969 ◽  
Vol 115 (4) ◽  
pp. 671-678 ◽  
Author(s):  
M. D. Herrington ◽  
A. O. Hawtrey
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Amino Acid ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
Inhibitory Effect ◽  
Bovine Mammary Gland ◽  
Free System ◽  
Enzyme Fraction

1. pH5 enzyme from non-lactating bovine mammary gland was found to contain potent inhibitors of protein synthesis in the rat liver cell-free system. These inhibitors affect (a) formation of aminoacyl-tRNA where tRNA represents transfer RNA, (b) transfer of labelled amino acids from rat liver amino[14C]acyl-tRNA to protein in rat liver polyribosomes, and (c) incorporation of 14C-labelled amino acids into peptide by rat liver polyribosomes supplemented with rat liver pH5 enzyme. 2. Increasing amounts of pH5 enzyme from bovine mammary gland progressively inhibited the incorporation of labelled amino acids into protein by a complete incorporating system from rat liver. Approx. 80% inhibition was observed at a concentration of 2mg. of protein of pH5 enzyme from bovine mammary gland. The inhibitory effect of the bovine pH5 enzyme fraction could not be overcome by the addition of increasing amounts of rat liver pH5 enzyme. 3. Fractionation of bovine pH5 enzyme with ammonium sulphate into four fractions showed that all the fractions inhibited the incorporation of 14C-labelled amino acids in the rat liver system, but to varying extents. The highest inhibition observed (90%) was exhibited by the 60%-saturated-ammonium sulphate fraction. 4. Heat treatment of bovine pH5 enzyme at various temperatures caused only a partial loss of its inhibitory effect on labelled amino acid incorporation by the rat liver system. Treatment at 105° for 5min. resulted in the bovine pH5 enzyme fraction losing 30% of its inhibitory activity. 5. pH5 enzyme from bovine mammary gland strongly inhibited the charging of rat liver tRNA in the presence of its own pH5 enzymes. 6. The transfer of labelled amino acids from rat liver amino[14C]acyl-tRNA to protein in a system containing rat liver polyribosomes and pH5 enzyme was almost completely inhibited by bovine pH5 enzyme at a concentration of 2mg. of protein of the enzyme fraction. 7. One of the inhibitors of various stages of protein synthesis in rat liver present in bovine pH5 enzyme was identified as an active ribonuclease, and the second inhibitor present was shown to be tRNA.

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