Separation of membrane-bound .gamma.-glutamyl transpeptidase from brush border transport and enzyme activities

Biochemistry ◽  
1980 ◽  
Vol 19 (11) ◽  
pp. 2367-2373 ◽  
Author(s):  
Richard D. Mamelok ◽  
Darlene F. Groth ◽  
Stanley B. Prusiner
Keyword(s):  
Brush Border ◽  
Enzyme Activities ◽  
Gamma Glutamyl Transpeptidase ◽  
Gamma Glutamyl ◽  
Membrane Bound ◽  
Glutamyl Transpeptidase

scholarly journals The effect of azaserine on glutamine uptake by rat renal brush-border membranes

1980 ◽  
Vol 192 (1) ◽  
pp. 119-126 ◽  
Author(s):  
B Y Hsu ◽  
C M Marshall ◽  
P D McNamara ◽  
S Segal
Keyword(s):  
Brush Border ◽  
Membrane Vesicles ◽  
Competitive Inhibitor ◽  
Transport Systems ◽  
Gamma Glutamyl Transpeptidase ◽  
Gamma Glutamyl ◽  
Transport Inhibition ◽  
Renal Brush Border Membrane ◽  
Glutamyl Transpeptidase ◽  
Renal Brush Border

Azaserine added directly to isolated rat renal brush-border membrane vesicles inhibits uptake of L-glutamine. Azaserine acts as a non-competitive inhibitor of the low-Km system for glutamine transport, but has no effect on the high-Km system. Preincubation of the vesicles with azaserine at 37 degrees C min is not required for transport inhibition to occur, although it is a requirement for gamma-glutamyl transpeptidase inhibition. Removal of azaserine from the vesicle preparation by repeated resuspensions in buffer results in a reversal of the transport inhibition but not in reversal of enzyme inhibition. Azaserine also inhibits vesicle uptake of L-proline and alpha-methyl D-glucoside, indicating a generalized effect on membrane transport systems. The data cast doubt on the postulate that gamma-glutamyl transpeptidase might act as the carrier mechanism for glutamine reabsorption by renal cortical cells.

Protein-lipid interactions in human small intestinal brush-border membranes

1989 ◽  
Vol 257 (5) ◽  
pp. G809-G817
Author(s):  
P. K. Dudeja ◽  
J. M. Harig ◽  
K. Ramaswamy ◽  
T. A. Brasitus
Keyword(s):  
Lipid Composition ◽  
Brush Border ◽  
Gamma Glutamyl Transpeptidase ◽  
Lipid Interactions ◽  
Gamma Glutamyl ◽  
Brush Border Membranes ◽  
Lipid Fluidity ◽  
Intestinal Brush Border ◽  
Small Intestinal ◽  
Glutamyl Transpeptidase

Brush-border membranes prepared from proximal and distal human small intestine were characterized with respect to lipid fluidity, lipid composition, and protein-lipid interactions. Steady-state fluorescence polarization and differential polarized phase fluorometry revealed that the "static" and "dynamic" rotational components of fluidity (assessed by r infinity values of 1,6-diphenyl-1,3,5-hexatriene and r values of 12-anthroylstearate, respectively) were greater in the distal membranes compared with their proximal counterparts. The lipid fluidity of distal brush-border membranes was also greater as measured by excimer/monomer fluorescence ratio intensities of pyrene decanoate. A lower molar ratio of cholesterol/phospholipid in the distal membranes was responsible for these regional fluidity differences. Lipid thermotropic transitions were detected at 26-28 degrees C using 1,6-diphenyl-1,3,5-hexatriene in proximal and distal membranes. Arrhenius plots of p-nitrophenylphosphatase and gamma-glutamyl transpeptidase activities demonstrated breakpoints in the vicinity of the lipid thermotropic transition temperatures (28-30 degrees C), whereas maltase and sucrase yielded a single activity slope over the range of 10-40 degrees C. Moreover, 50 mM benzyl alcohol fluidized proximal brush-border membranes and increased p-nitrophenylphosphatase activity in this membrane. This agent also shifted the phase transition temperature of the membrane and breakpoint temperature of this enzymatic activity from approximately 28 degrees C to 19 degrees C. These findings demonstrate that differences in human small intestinal brush-border membrane lipid fluidity and lipid composition exist between proximal and distal regions of this organ. Furthermore, alterations in fluidity and/or lipid composition modulate p-nitrophenylphosphatase and gamma-glutamyl transpeptidase but not sucrase or maltase activities in these membranes.

Relationship Between Gamma-glutamyl Transpeptidase Activity and Inflammatory Response in Lichen Planus

2018 ◽  
Vol 69 (3) ◽  
pp. 739-743 ◽  
Author(s):  
Madalina Irina Mitran ◽  
Ilinca Nicolae ◽  
Corina Daniela Ene ◽  
Cristina Iulia Mitran ◽  
Clara Matei ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Lichen Planus ◽  
Inflammatory Process ◽  
Molecular Mechanisms ◽  
Functional Adaptation ◽  
Physical Factors ◽  
Inflammatory Disorder ◽  
Gamma Glutamyl Transpeptidase ◽  
Gamma Glutamyl ◽  
Glutamyl Transpeptidase

Chemicals used in the manufacture of synthetic fibers have been associated with undesirable side effects such as itching or skin lesions and it seems that they are involved in the induction of pathological processes such as oxidative stress and inflammation. Lichen planus (LP) can be regarded as an inflammatory disorder, chemical and physical factors playing an important role in the perpetuation of the inflammatory process. Gamma-glutamyl transpeptidase (GGT) plays an important role in the preservation of skin architecture and modulation of skin inflammation. In this study, we found that GGT activity is increased in LP patients with mild inflammation, whilst GGT is inactivated under conditions of severe inflammation. Therefore, GGT is involved in the inflammatory process, but there is no a positive correlation between its activity and the intensity of the inflammatory response. This functional adaptation of the enzyme may be due to down-regulation of its synthesis under free radical overload conditions. Understanding the molecular mechanisms involved in the modulation of intracellular redox homeostasis is an important step in the pharmacological management of patients with LP.

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