Search results for "PHOSPHATASE"
showing 10 items of 499 documents
Lysosomal alterations in heart and liver of mice treated with doxorubicin.
1985
This study was carried out to evaluate the influence of long-term treatment with doxorubicin (DXR) (4mg/kg IV for 5 weeks) on heart and liver lysosomes of mice. We evaluated the variations in both total and "sedimentable" enzyme activity of cathepsin D, which is the major endopeptidase of myocites and probably involved in physiologic and pathologic degradation of actomyosin and mitochondria, and that of acid phosphatase, which is more prominent in interstitial cells. Our results show that marked changes occur in both total and sedimentable enzyme activity of cathepsin D in the heart of treated animals and to a lesser extent in the liver. In contrast, no modification of either total or sedim…
Development of hydroxysteroid sulfotransferase-deficient lesions during hepatocarcinogenesis in rats
1993
Rat liver cytosolic hydroxysteroid sulfotransferases form highly reactive sulfuric acid esters from some benzylic alcohols, such as 1-hydroxymethylpyrene. In this study we examined the expression of hydroxysteroid sulfotransferase a (STa) in carcinogen-induced enzyme-altered, presumably preneoplastic, rat liver foci. Female Wistar rats were given a single i.p. injection of diethylnitrosamine (0.15 mumol/g body wt) 1 day after birth to induce the liver foci. After weaning, rats were given 1-hydroxymethylpyrene or phenobarbital continuously in their diet (250 or 500 p.p.m. respectively) for a total of 120 days. Carcinogen-induced liver foci were identified by a change in the marker enzyme ade…
Parthenolide induces superoxide anion production by stimulating EGF receptor in MDA-MB-231 breast cancer cells
2013
The sesquiterpene lactone parthenolide (PN) has recently attracted considerable attention because of its anti-microbial, anti-inflammatory and anticancer effects. However, the mechanism of its cytotoxic action on tumor cells remains scarcely defined. We recently provided evidence that the effect exerted by PN in MDA-MB-231 breast cancer cells was mediated by the production of reactive oxygen species (ROS). The present study shows that PN promoted the phosphorylation of EGF receptor (phospho-EGFR) at Tyr1173, an event which was observed already at 1 h of incubation with 25 µM PN and reached a peak at 8-16 h. This effect seemed to be a consequence of ROS production, because N-acetylcystein…
Ester Hydrolases, ATPases and Carboanhydrases
1994
Many biomolecules are esterified with carbonic acid, phosphoric acid or sulphuric acid. The enzymes responsible for the hydrolytic cleavage of the esters are the carboxylester hydrolases, phosphoesterases and sulphatases. In addition to the phosphomonoesterases, we will also consider the phosphodiesterases and nucleases that are specific for cAMP and cGMP, as well as the ATPases that cleave phosphoric acid anhydride bonds. The ion-transporting ATPases will be discussed together with comparative biochemical data on ion channels. The chapter ends with a discussion of carboanhydrases.
Morphogenetically active scaffold for osteochondral repair (Polyphosphate/alginate/N,O-carboxymethyl chitosan)
2016
Here we describe a novel bioinspired hydrogel material that can be hardened with calcium ions to yield a scaffold material with viscoelastic properties matching those of cartilage. This material consists of a negatively charged biopolymer triplet, composed of morphogenetically active natural inorganic polyphosphate (polyP), along with the likewise biocompatible natural polymers N,O-carboxymethyl chitosan (N,O-CMC) and alginate. The porosity of the hardened scaffold material obtained after calcium exposure can be adjusted by varying the pre-processing conditions. Various compression tests were applied to determine the local (nanoindentation) and bulk mechanical properties (tensile/compressio…
Purification and characterization of two exopolyphosphatases from the marine sponge Tethya lyncurium
1995
Abstract Two exopolyphosphatases (exopolyphosphatase I and II; EC 3.6.1.11) which release orthophosphate from inorganic polyphosphates have been detected and purified for the first time from a marine sponge, Tethya lyncurium . Exopolyphosphatase I has a molecular mass of 45 kDa, a pH optimum of 5.0 and does not require divalent cations for activity, while exopolyphosphatase II has a molecular mass of 70 kDa, a pH optimum of 7.5 and displays optimal activity in the presence of Mg 2+ ions. Final purification of the enzymes could be achieved by affinity chromatography on polyphosphate-modified zirconia. The mode of action of both enzymes was found to be processive. Orthophosphate is the sole p…
Mammalian intestinal alkaline phosphatase acts as highly active exopolyphosphatase.
2001
Recent results revealed that inorganic polyphosphates (polyP), being energy-rich linear polymers of orthophosphate residues known from bacteria and yeast, also exist in higher eukaryotes. However, the enzymatic basis of their metabolism especially in mammalian cells is still uncertain. Here we demonstrate for the first time that alkaline phosphatase from calf intestine (CIAP) is able to cleave polyP molecules up to a chain length of about 800. The enzyme acts as an exopolyphosphatase degrading polyP in a processive manner. The pH optimum is in the alkaline range. Divalent cations are not required for catalytic activity but inhibit the degradation of polyP. The rate of hydrolysis of short-ch…
Bacillus thuringiensis Cry1Ac Toxin-Binding and Pore-Forming Activity in Brush Border Membrane Vesicles Prepared from Anterior and Posterior Midgut R…
2008
ABSTRACT It is generally accepted that Bacillus thuringiensis Cry toxins insert into the apical membrane of the larval midgut after binding to specific receptors, and there is evidence that the distribution of binding molecules along the midgut is not uniform. By use of the voltage-sensitive dye DiSC 3 (5) and 125 I-labeled Cry1Ac, we have measured the effect of Cry1Ac in terms of permeabilization capacity and of binding parameters on brush border membrane vesicles (BBMV) prepared from the anterior and the posterior regions of the larval midgut from two insect species, Manduca sexta and Helicoverpa armigera . The permeabilizing activity was significantly higher with BBMV from the posterior …
Characterization of the Epithelial Permeation Enhancing Effect of Basic Butylated Methacrylate Copolymer—In Vitro Studies
2008
Membrane destabilizing properties and increased efflux of doxorubicin from liposomes caused by basic butylated methacrylate copolymer (BBMC), better known under its commercial trade name EUDRAGIT E, have been described in the scientific literature. Here, we investigated the effect of BBMC on suspended and filter-grown Caco2 cells with respect to apical-to-basal transport and membrane permeabilization using transport assays, trypan blue exclusion assay, measurements of transepithelial electrical resistance (TEER), confocal laser scanning microscopy, and transmission electron microscopy. The effect of inhibiting protein phosphatase 2A (PP2A) by okadaic acid was investigated by measuring TEER,…
Tightly bound to DNA proteins: possible universal substrates for intranuclear processes.
2011
Tightly bound to DNA proteins (TBPs) are a protein group that remains attached to DNA after its deproteinization by phenol, chloroform or salting-out. TBP are bound to DNA with covalent phosphotriester or non-covalent ion and hydrogen bonds. They appear to be a vast protein group involved in numerous intranuclear processes. The TBPs fraction co-purified with DNA deproteinized by mild procedures is extremely heterogeneous, tissue and species-specific. The protein fraction co-purified with DNA after harsh deproteinization procedures appears to be formed from few polypeptides common to different species and tissues. Interaction sites between DNA and TBPs depend on the physiological status of t…