scholarly journals Formation of malate from glyoxylate in animal tissues

1971 ◽  
Vol 121 (3) ◽  
pp. 447-452 ◽  
Author(s):  
Chi-Chin Liang ◽  
Lo-Chang Ou
Keyword(s):  
Rat Liver ◽  
Liver Homogenate ◽  
Animal Tissues

1. Incubation of rat liver homogenate with [1-14C]glyoxylate, ATP and acetate shows a rapid sequential incorporation of radioactivity into malate, oxaloacetate and citrate. 2. In liver from normal rats the rate of the formation of each substance in question is higher than that in liver from thiamin-deficient rats. 3. The net accumulation of malate is greater with liver from thiamin-deficient rats. Its further metabolism is retarded, it is suggested, by inhibitors formed by a condensation of glyoxylate and oxaloacetate.

Recent investigations on the nature of sterol intermediates in the biosynthesis of cholesterol

1972 ◽  
Vol 180 (1059) ◽  
pp. 125-146 ◽  
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Rat Liver ◽  
Liver Homogenate ◽  
Methyl Groups ◽  
Double Bonds ◽  
Animal Tissues ◽  
Methyl Group ◽  
Chromatographic Methods

Lanosterol(4,4,14α-trimethyl-cholesta-8,24-dien-3β-ol) has been proposed as the primary product of the cyclization of 2,3-epoxysqualene in animal tissues. Enzymic conversion of lanosterol to cholesterol requires reduction of the ∆ 24 double bond, removal of the three extra methyl groups, and shift of the nuclear double bond from ∆ 8 position to the ∆ 5 position. Until very recently, all of the proposed sterol intermediates in the biosynthesis of cholesterol possessed nuclear double bonds in the ∆ 8 , ∆ 7 , ∆ 5,7 or ∆ 5 positions. Consideration of possible mechanisms for the removal of the methyl group at carbon atom 14 of sterol precursors led to our demonstration of the presence of cholest-8(14)-en-3β-ol in animal tissues and establishment of the convertibility of this sterol to cholesterol in rat liver homogenate preparations. Reports (from other laboratories) of the stereospecific loss of the 15α-hydrogen of lanosterol upon enzymic conversion to cholesterol led to the demonstration of the convertibility of cholesta-8,14-dien-3β-ol, cholesta-7,14-dien-3β-ol, 14α-methyl-cholest-7-en-3β,15-diol, cholest-8(14)-en-3β,15α-diol, and cholest-8(14)-en-3β,15β-diol to cholesterol in rat liver preparations. We have recently developed chromatographic methods permitting the resolution of all of the C 27 sterols in question. The results of recent experiments directed towards an understanding of the detailed metabolism of these compounds are presented herein.

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.

Purification and partial characterization of cysteine-glutamate transaminase from rat liver

1977 ◽  
Vol 55 (9) ◽  
pp. 958-964 ◽  
Author(s):  
M. P. C. Ip ◽  
R. J. Thibert ◽  
D. E. Schmidt Jr.
Keyword(s):  
Molecular Weight ◽  
Rat Liver ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Liver Homogenate ◽  
Polyacrylamide Gel ◽  
Gel Chromatography ◽  
Labile Hydrogen ◽  
Apparent Homogeneity

Cysteine-glutamate transaminase (cysteine aminotransferase; EC 2.6.1.3) has been purified 149-fold to an apparent homogeneity giving a specific activity of 2.09 IU per milligram of protein with an overall yield of 15%. The isolation procedures involve the preliminary separation of a crude rat liver homogenate which was submitted sequentially to ammonium sulfate fractionation, TEAE-cellulose column chromatography, ultrafiltration, and isoelectrofocusing. The final product was homogenous when examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS). A minimal molecular weight of 83 500 was determined by Sephadex gel chromatography. The molecular weight as estimated by polyacrylamide gel electrophoresis in the presence of SDS was 84 000. The purified enzyme exhibited a pH optimum at 8.2 with cysteine and α-ketoglutarate as substrates. The enzyme is inactivated slowly when kept frozen and is completely inactivated if left at room temperature for 1 h. The enzyme does not catalyze the transamination of α-methyl-DL-cysteine, which, when present to a final concentration of 10 mM, exhibits a 23.2% inhibition of transamination of 30 mM of cysteine. The mechanism apparently resembles that of aspartate-glutamate transaminase (EC 2.6.1.1) in which the presence of a labile hydrogen on the alpha-carbon in the substrate is one of the strict requirements.

Studies of the metabolism of thiazolidine carboxylic acid by rat liver homogenate

1956 ◽  
Vol 22 (3) ◽  
pp. 558-564 ◽  
Author(s):  
D. Cavallini ◽  
C. De Marco ◽  
B. Mondovì ◽  
F. Trasarti
Keyword(s):  
Carboxylic Acid ◽  
Rat Liver ◽  
Liver Homogenate

Effect of adrenalectomy, sham operation or ACTH on the cortisol metabolizing enzymes of rat liver homogenate

Metabolism ◽  
1965 ◽  
Vol 14 (3) ◽  
pp. 264-270 ◽  
Author(s):  
R. Deckx ◽  
P. De Moor ◽  
C. Denef ◽  
J. Raus
Keyword(s):  
Rat Liver ◽  
Liver Homogenate ◽  
Sham Operation ◽  
Metabolizing Enzymes
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