scholarly journals Histone 2A stimulates glucose-6-phosphatase activity by permeabilization of liver microsomes

2002 ◽  
Vol 367 (2) ◽  
pp. 505-510 ◽  
Author(s):  
Angelo BENEDETTI ◽  
Rosella FULCERI ◽  
Bernard B. ALLAN ◽  
Pamela HOUSTON ◽  
Andrey L. SUKHODUB ◽  
...  
Keyword(s):  
Phosphatase Activity ◽  
Liver Microsomes ◽  
Catalytic Site ◽  
Microsomal Membrane ◽  
Dose Effect ◽  
Free Access ◽  
Microsomal Enzyme ◽  
Inhibitory Effects ◽  
Effect Curve ◽  
Udp Glucuronosyltransferase

Histone 2A increases glucose-6-phosphatase activity in liver microsomes. The effect has been attributed either to the conformational change of the enzyme, or to the permeabilization of microsomal membrane that allows the free access of substrate to the intraluminal glucose-6-phosphatase catalytic site. The aim of the present study was the critical reinvestigation of the mechanism of action of histone 2A. It has been found that the dose-effect curve of histone 2A is different from that of detergents and resembles that of the pore-forming alamethicin. Inhibitory effects of EGTA on glucose-6-phosphatase activity previously reported in histone 2A-treated microsomes have been also found in alamethicin-permeabilized vesicles. The effect of EGTA cannot therefore simply be an antagonization of the effect of histone 2A. Histone 2A stimulates the activity of another latent microsomal enzyme, UDP-glucuronosyltransferase, which has an intraluminal catalytic site. Finally, histone 2A renders microsomal vesicles permeable to non-permeant compounds. Taken together, the results demonstrate that histone 2A stimulates glucose-6-phosphatase activity by permeabilizing the microsomal membrane.

scholarly journals Histone II-A stimulates glucose-6-phosphatase and reveals mannose-6-phosphatase activities without permeabilization of liver microsomes

1995 ◽  
Vol 310 (1) ◽  
pp. 221-224 ◽  
Author(s):  
J F St-Denis ◽  
B Annabi ◽  
H Khoury ◽  
G van de Werve
Keyword(s):  
Substrate Specificity ◽  
Membrane Permeability ◽  
Phosphatase Activity ◽  
Liver Microsomes ◽  
Microsomal Membrane ◽  
Phosphatase Activities ◽  
Phosphate Hydrolysis ◽  
Mannose 6 Phosphate ◽  
Stimulation Of

The effect of histone II-A on glucose-6-phosphatase and mannose-6-phosphatase activities was investigated in relation to microsomal membrane permeability. It was found that glucose-6-phosphatase activity in histone II-A-pretreated liver microsomes was stimulated to the same extent as in detergent-permeabilized microsomes, and that the substrate specificity of the enzyme for glucose 6-phosphate was lost in histone II-A-pretreated microsomes, as [U-14C]glucose-6-phosphate hydrolysis was inhibited by mannose 6-phosphate and [U-14C]mannose 6-phosphate hydrolysis was increased. The accumulation of [U-14C]glucose from [U-14C]glucose 6-phosphate into untreated microsomes was completely abolished in detergent-treated vesicles, but was increased in histone II-A-treated microsomes, accounting for the increased glucose-6-phosphatase activity, and demonstrating that the microsomal membrane was still intact. The stimulation of glucose-6-phosphatase and mannose-6-phosphatase activities by histone II-A was found to be reversed by EGTA. It is concluded that the effects of histone II-A on glucose-6-phosphatase and mannose-6-phosphatase are not caused by the permeabilization of the microsomal membrane. The measurement of mannose-6-phosphatase latency to evaluate the intactness of the vesicles is therefore inappropriate.

The inhibitory effects of vancomycin on rat bone marrow–derived mesenchymal stem cell differentiation

2021 ◽  
pp. 1-5
Author(s):  
Kari Hanson ◽  
Carly Isder ◽  
Kristen Shogren ◽  
Anthony L. Mikula ◽  
Lichun Lu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Alkaline Phosphatase ◽  
Osteogenic Differentiation ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
High Dose ◽  
Inhibitory Effects ◽  
Alizarin Red ◽  
Osteogenic Factors

OBJECTIVE The use of intrawound vancomycin powder in spine surgery has been shown to decrease the rate of surgical site infections; however, the optimal dose is unknown. High-dose vancomycin inhibits osteoblast proliferation in vitro and may decrease the rate of solid arthrodesis. Bone marrow–derived mesenchymal stem cells (BMSCs) are multipotent cells that are a source of osteogenesis in spine fusions. The purpose of this study was to determine the effects of vancomycin on rat BMSC viability and differentiation in vitro. METHODS BMSCs were isolated from the femurs of immature female rats, cultured, and then split into two equal groups; half were treated to stimulate osteoblastic differentiation and half were not. Osteogenesis was stimulated by the addition of 50 µg/mL l-ascorbic acid, 10 mM β-glycerol phosphate, and 0.1 µM dexamethasone. Vancomycin was added to cell culture medium at concentrations of 0, 0.04, 0.4, or 4 mg/mL. Early differentiation was determined by alkaline phosphatase activity (4 days posttreatment) and late differentiation by alizarin red staining for mineralization (9 days posttreatment). Cell viability was determined at both the early and late time points by measurement of formazan colorimetric product. RESULTS Viability within the first 4 days decreased with high-dose vancomycin treatment, with cells receiving 4 mg/mL vancomycin having 40%–60% viability compared to the control. A gradual decrease in alizarin red staining and nodule formation was observed with increasing vancomycin doses. In the presence of the osteogenic factors, vancomycin did not have deleterious effects on alkaline phosphatase activity, whereas a trend toward reduced activity was seen in the absence of osteogenic factors when compared to osteogenically treated cells. CONCLUSIONS Vancomycin reduced BMSC viability and impaired late osteogenic differentiation with high-dose treatment. Therefore, the inhibitory effects of high-dose vancomycin on spinal fusion may result from both reduced BMSC viability and some impairment of osteogenic differentiation.

Adenine-related compounds modulate UDP-glucuronosyltransferase (UGT) activity in mouse liver microsomes

Xenobiotica ◽  
2021 ◽  
pp. 1-25
Author(s):  
Shoji Nakamura ◽  
Ryohei Yamashita ◽  
Yuu Miyauchi ◽  
Yoshitaka Tanaka ◽  
Yuji Ishii
Keyword(s):  
Mouse Liver ◽  
Liver Microsomes ◽  
Udp Glucuronosyltransferase ◽  
Related Compounds

The point of transition on the dose-effect curve as a reference point in the evaluation of in vitro toxicity data

2012 ◽  
Vol 32 (10) ◽  
pp. 843-849 ◽  
Author(s):  
Salomon Sand ◽  
Joakim Ringblom ◽  
Helen Håkansson ◽  
Mattias Öberg
Keyword(s):  
Reference Point ◽  
Dose Effect ◽  
In Vitro Toxicity ◽  
Toxicity Data ◽  
Effect Curve

Antioxidant and Antifungal Properties of Benzimidazole Derivatives

2010 ◽  
Vol 65 (9-10) ◽  
pp. 537-542 ◽  
Author(s):  
Canan Kuş ◽  
Fatma Sözüdönmez ◽  
Benay Can-Eke ◽  
Tülay Çoban
Keyword(s):  
Lipid Peroxidation ◽  
Free Radical ◽  
Radical Scavenging ◽  
Liver Microsomes ◽  
Thiobarbituric Acid ◽  
Benzimidazole Derivatives ◽  
Rat Liver Microsomes ◽  
Inhibitory Effects ◽  
Stable Free Radical ◽  
Radical Scavenging Properties

Antioxidant and radical scavenging properties of a series of 2-[4-(substituted piperazin-/ piperidin-1-ylcarbonyl)phenyl]-1H-benzimidazole derivatives were examined. Free radical scavenging properties of compounds 11-30 and 33 were evaluated for the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide anion radical. In addition the inhibitory effects on the NADPH-dependent lipid peroxidation levels were determined by measuring the formation of 2-thiobarbituric acid reactive substances (TBARS) using rat liver microsomes. Compound 33 which has a p-fluorobenzyl substitutent at position 1 exhibited the strongest inhibition (83%) of lipid peroxidation at a concentration of 10-3 M, while the nonsubstituted analogue 13 caused 57% inhibition. This result is fairly consistent with the antimicrobial activity results against both Staphylococcus aureus and Candida albicans.

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