scholarly journals The mechanism of guanosine triphosphate depletion in the liver after a fructose load. The role of fructokinase

1985 ◽  
Vol 228 (3) ◽  
pp. 667-671 ◽  
Author(s):  
M I Phillips ◽  
D R Davies
Keyword(s):  
Rat Liver ◽  
Intravenous Administration ◽  
Liver Homogenate ◽  
Guanosine Triphosphate ◽  
Phosphate Donor ◽  
Single Enzyme

A Sephadex G-25 filtrate of a 100 000g supernatant of rat liver homogenate was shown to be able to phosphorylate fructose, with GTP as the phosphate donor. Attempts to separate ATP- and GTP-dependent fructokinase activities failed, indicating that there is a single enzyme able to use both nucleotides. With a partially purified enzyme, Km values for fructose of 0.83 and 0.56 mM were found with ATP and GTP as substrates respectively. Km values of 1.53 and 1.43 mM were found for GTP and ATP respectively. Both ADP and GDP inhibited the GTP- and ATP-dependent fructokinase activity. We conclude that the depletion of hepatic GTP caused by intravenous administration of fructose to mice and rats can be explained simply by the utilization of the nucleotide by fructokinase.

A STUDY ON THE "IN VITRO" SYNTHESIS OF CITRULLINE: PART II. EFFECT OF GLUTAMIC ACID AND DERIVATIVES IN THE PRESENCE OF FUMARIC ACID

1964 ◽  
Vol 42 (9) ◽  
pp. 1325-1330 ◽  
Author(s):  
René Charbonneau ◽  
Louis Berlinguet
Keyword(s):  
Glutamic Acid ◽  
Rat Liver ◽  
Fumaric Acid ◽  
Liver Homogenate ◽  
Particulate Fraction ◽  
In Vitro Synthesis ◽  
System L ◽  
Acyl Derivatives

The role of N-carbamyl, N-acetyl, and L-glutamic acids with and without fumaric acid on the "in vitro" synthesis of citrulline was studied by using a particulate fraction obtained from a rat liver homogenate and a partially purified citrulline-synthesizing enzyme system. In the presence of a particulate fraction of rat liver homogenate, N-carbamyl and N-acetyl-L-glutamic acids are unable to replace L-glutamic acid, which is essential for citrulline biosynthesis. However, in the presence of fumaric acid, they both give a better synthesis of citrulline than L-glutamic acid alone. It is postulated that the acyl derivatives serve only in the transport of "activated CO2" whereas fumaric acid enters the citric acid to furnish the essential ATP molecules. Glutamic acid would be able to perform both functions. However, in the presence of a system containing partially purified citrulline-synthesizing enzymes, L-glutamic acid is unable to replace N-carbamyl and N-acetyl-L-glutamic acids with or without fumaric acid. In such a system, L-glutamic acid cannot serve in the transport of "activated CO2". It is postulated that L-glutamic acid must be acetylated prior to its utilization in this respect.With the particulate fraction of rat liver homogenate, N-allyl aspartic acid inhibits totally the synthesis of citrulline both in the presence and absence of fumaric acid with or without glutamic or N-acetyl glutamic acids. It probably interferes with the transport of "activated CO2".

scholarly journals Intermediate reactions in the binding of aminoacyl-transfer ribonucleic acid to rat liver ribosomes. The role of guanosine triphosphate

1972 ◽  
Vol 126 (4) ◽  
pp. 933-943 ◽  
Author(s):  
J. Hradec
Keyword(s):  
Rat Liver ◽  
Ternary Complex ◽  
Cellulose Nitrate ◽  
Stable Complex ◽  
Bacterial Cells ◽  
Guanosine Triphosphate ◽  
Binding Reaction ◽  
Aminoacyl Transfer ◽  
Liver Ribosomes

1. Transferase I from rat liver binds relatively low quantities of GTP when incubated with this nucleotide in the absence of aminoacyl-tRNA. 2. Transferase I reacts with both aminoacyl-tRNA and GTP to form a relatively stable complex that is retained on cellulose nitrate filters. The ternary complex transferase I–aminoacyl-tRNA–GTP is also formed when the transferase I–aminoacyl-tRNA complex is incubated with GTP or during the incubation of the transferase I–GTP complex with aminoacyl-tRNA. Synthesis of this complex does not require the presence of Mg2+. 3. In the presence of Mg2+ the ternary complex becomes readily bound to ribosomes without requirements for any other cofactors. 4. An extensive cleavage of GTP takes place when aminoacyl-tRNA becomes bound to ribosomes. 5. The low interdependence of reactions leading to the formation of transferase I complexes with aminoacyl-tRNA and GTP indicates that the mechanisms of the binding reaction in mammalian systems may be different from those in bacterial cells.

scholarly journals Biotransformation of Timosaponin BII into Seven Characteristic Metabolites by the Gut Microbiota

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3861
Author(s):  
Guo-Ming Dong ◽  
Hang Yu ◽  
Li-Bin Pan ◽  
Shu-Rong Ma ◽  
Hui Xu ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Rat Liver ◽  
Pharmacological Activity ◽  
Liver Homogenate ◽  
Intestinal Flora ◽  
Important Indicator ◽  
Metabolic Characteristics ◽  
Metabolic Behavior ◽  
First Time ◽  
Rat Liver Microsome

Timosaponin BII is one of the most abundant Anemarrhena saponins and is in a phase II clinical trial for the treatment of dementia. However, the pharmacological activity of timosaponin BII does not match its low bioavailability. In this study, we aimed to determine the effects of gut microbiota on timosaponin BII metabolism. We found that intestinal flora had a strong metabolic effect on timosaponin BII by HPLC-MS/MS. At the same time, seven potential metabolites (M1-M7) produced by rat intestinal flora were identified using HPLC/MS-Q-TOF. Among them, three structures identified are reported in gut microbiota for the first time. A comparison of rat liver homogenate and a rat liver microsome incubation system revealed that the metabolic behavior of timosaponin BII was unique to the gut microbiota system. Finally, a quantitative method for the three representative metabolites was established by HPLC-MS/MS, and the temporal relationship among the metabolites was initially clarified. In summary, it is suggested that the metabolic characteristics of gut microbiota may be an important indicator of the pharmacological activity of timosaponin BII, which can be applied to guide its application and clinical use in the future.

Role of nitric oxide in hepatic and pulmonary injury following ischemia-reperfusion of rat liver

2003 ◽  
Vol 124 (4) ◽  
pp. A719-A720
Author(s):  
Yuji Takamatsu ◽  
Kazuo Shimada ◽  
Koji Yamaguchi ◽  
Kazuo Chijiiwa ◽  
Masao Tanaka
Keyword(s):  
Nitric Oxide ◽  
Rat Liver ◽  
Ischemia Reperfusion ◽  
Pulmonary Injury

scholarly journals Role of hepatic lipase in the uptake and processing of chylomicron remnants in rat liver.

1994 ◽  
Vol 35 (4) ◽  
pp. 709-720
Author(s):  
S Shafi ◽  
S E Brady ◽  
A Bensadoun ◽  
R J Havel
Keyword(s):  
Rat Liver ◽  
Hepatic Lipase ◽  
Chylomicron Remnants

scholarly journals A Guanosine Triphosphate-dependent Acyl Coenzyme A Synthetase from Rat Liver Mitochondria

1967 ◽  
Vol 242 (9) ◽  
pp. 2111-2115 ◽  
Author(s):  
Lauro Galzigna ◽  
Carlo R. Rossi ◽  
Lodovico Sartorelli ◽  
David M. Gibson
Keyword(s):  
Rat Liver ◽  
Coenzyme A ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Guanosine Triphosphate ◽  
Acyl Coenzyme A
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