Preparation and galactosyltransferase acceptor activity of derivatives of antifreeze glycoproteins of an Antarctic fish

1977 ◽  
Vol 55 (8) ◽  
pp. 886-893 ◽  
Author(s):  
W. Thomas Shier ◽  
Gary J. Roloson
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
Antarctic Fish ◽  
Helical Structure ◽  
Structural Features ◽  
Rat Liver Microsomes ◽  
Antifreeze Glycoproteins ◽  
Galactosyl Transferase ◽  
Acceptor Activity ◽  
The Antarctic

A series of 12 closely related glycoproteins containing α-linked N-acetyl-D-galactosamine (GalNAc) as the sole carbohydrate moiety have been prepared by degradation of the antifreeze glycoproteins from the serum of the Antarctic fish Trematomus borchgrevinki. The polypeptide moieties of these glycoproteins contain substitutions in the normal -Ala-Ala-Thr- repeating tripeptide sequence which introduce alterations in the amount of α-helical structure and the density of acceptor sites, and theoretically also in the amount of rigidity, polarity, and hydrophobicity of the polypeptide. Of these alterations only density of acceptor sites has a statistically significant effect on the ability of the [Formula: see text] moiety to act as a substrate for galactosyl-transferase (EC 2.4.1.22) activity solubilized from rat liver microsomes. This result suggests that in the biosynthesis of rat liver glycoproteins these structural features of the polypeptide moiety of glycoproteins are not part of the substrate specificity of the galactosyltransferase activity that transfers the second monosaccharide. Hence, these structural features do not play a major role in determining the structure of the threonine-linked oligosaccharide after its synthesis has been initiated.

INHIBITION OF14C-ESTRONE METABOLISM IN RAT LIVER MICROSOMES BY 2-HYDROXYESTROGENS AND RELATED COMPOUNDS

1965 ◽  
Vol 43 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Catherine Lazier ◽  
P. H. Jellinck
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
Structural Features ◽  
Water Soluble ◽  
Rat Liver Microsomes ◽  
Synthetic Estrogen ◽  
Natural Estrogens ◽  
Water Soluble Protein ◽  
Inhibition Studies ◽  
Related Compounds

Inhibition studies with compounds having structural features in common with the natural estrogens have shown that 2-hydroxyestrone and 2-hydroxyestradiol are potent inhibitors of the rat liver microsomal system, which converts estrone to water-soluble protein-bound products. Simple phenols and naphthols hydroxylated in the ortho and para positions were also found to be good inhibitors, but the corresponding meta-hydroxylated compounds, as well as various anthraquinones and estrogens substituted in the 6, 10, or 16 positions, were inactive in this respect. The synthetic estrogen, hexestrol, lost its inhibitory activity on conversion to dihydroxy hexestrol, a nonestrogenic analogue. The type of inhibition produced by 2-hydroxyestrone, equilenin, diethylstilbestrol, and menadione has been determined by the Lineweaver–Burk method and shown to be competitive for the first three of these compounds.

Metabolic Analysis of Triptolide Microspheres in Human, Dog, Rabbit and Rat Liver Microsomes with UPLC-MS/MS Method

2020 ◽  
Vol 17 ◽  
Author(s):  
LiJuan Wang ◽  
Yan Liu ◽  
Rui Li ◽  
DongXian He
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
Internal Standard ◽  
Gradient Elution ◽  
Rat Liver Microsomes ◽  
Good Precision ◽  
Kinetics Parameters ◽  
Measure Concentration ◽  
Standard Curve ◽  
Variation Of Parameters

Objectives: Triptolide (TPL) has been shown to have a good clinical effect on rheumatoid arthritis (RA). We designed TPL microspheres (TPL-MS) and investigated its metabolic behavior in human, dog, rabbit and rat liver microsomes (HLM, DLM, RLM and SDRLM) with UPLC-MS/MS method. Methods: First, a UPLC-MS/MS method was established to measure concentration of TPL in samples. The sample was separated on a C18 column (2.1×100 mm, 1.8μm) and eluted with a gradient elution. The precursor ion/product ion were m/z 378.1/361.0 for TPL and 260.0/116.2 for the internal standard. Then T1/2, Vmax and CLint were calculated from the above data. Finally, the metabolites of TPL-MS were identified by high-resolution UPLC-MS/MS. The sample was separated on a C18 column (2.1×100 mm, 2.2 μm) and eluted with isocratic elution. Mass spectrometric detection was carried out on a thermo Q-exactive mass spectrometer with HESI. The scanning range of precursor ions was from m/z 50 to m/z 750. Result and Discussion: Through several indicators including standard curve, precision, accuracy, stability, matrix effect and recovery rate, the enzymatic kinetics parameters including T1/2, Vmax and CLint were completed. Several metabolites of TPL-MS were identified. Conclusion: UPLC-MS/MS method is an accurate and sensitive method for determination of TPL in liver microsome samples with good precision, accuracy and stability. The variation of parameters indicated that the microspheres can delay the elimination of TPL in liver microsomes. The metabolism of TPL-MS varied among species, but no new metabolites appeared.

scholarly journals The metabolism of gelsevirine in human, pig, goat and rat liver microsomes

2021 ◽  
Author(s):  
Hua‐Hai Zhang ◽  
Wen‐Jia Yang ◽  
Ya‐Jun Huang ◽  
Wen‐Jing Li ◽  
Shuo‐Xin Zhang ◽  
...  
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
Rat Liver Microsomes

scholarly journals Detoxification of the tricyclic antidepressant opipramol and its analog – IS-noh by UGT enzymes before and after activation by phase I enzymes in rat liver microsomes

2021 ◽  
Author(s):  
Anna Mieszkowska ◽  
Koleta Hemine ◽  
Anna Skwierawska ◽  
Ewa Augustin ◽  
Zofia Mazerska
Keyword(s):  
Phase I ◽  
Rat Liver ◽  
Phase Ii ◽  
Oxidation Product ◽  
Liver Microsomes ◽  
Correct Selection ◽  
Rat Liver Microsomes ◽  
Recombinant Enzymes ◽  
Data Set ◽  
Phase I Enzymes

AbstractThe present studies were carried out to evaluate the simultaneous one-pot metabolism of opipramol (IS-opi) and analog (IS-noh) by phase I and phase II enzymes present in rat liver microsomes (RLM) as an alternative to separate testing with recombinant enzymes. This approach allows for more time-saving and cost-effective screening of the metabolism of newly discovered drugs. We also considered that the lack of results for phase II, including UGT, often creates problems in correct selection of valuable compounds. Moreover, microsomes data set is richer in the contest and provides medical scientist to determine also the susceptibility of drugs to undergo phase I and then phase II. In the present work, we have shown that IS-noh was metabolized in vitro by phase I enzymes to the oxidation product, which was next transformed with UGTs to glucuronide. The results showed also that the previously known oxidation product of opipramol was changed to previously no reported glucuronidation product by UDP-glucuronosyltransferases. In addition, unlike IS-noh, opipramol did not prove to be the substrate for UGTs. Therefore, tricyclic antidepressants depending on the structure can trigger a different response after contact with UGT enzymes. Some will metabolize directly with UGTs, others only after activation by phase I enzymes.

scholarly journals Oxidation of docosahexaenoic acid by rat liver microsomes.

1984 ◽  
Vol 259 (9) ◽  
pp. 5776-5783 ◽  
Author(s):  
M VanRollins ◽  
R C Baker ◽  
H W Sprecher ◽  
R C Murphy
Keyword(s):  
Docosahexaenoic Acid ◽  
Rat Liver ◽  
Liver Microsomes ◽  
Rat Liver Microsomes
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