Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Exposure of beta L-crystallin to oxidizing free radicals enhances its susceptibility to transglutaminase activity.

ABSTRACT: 1. The effects of free radicals on the capacity of beta L-crystallin to act as a substrate for the enzyme transglutaminase were investigated. 2. beta L-Crystallin was exposed to defined radical species that were generated radiolytically, and transglutaminase activity, using the modified protein as substrate, was subsequently measured by monitoring the incorporation of [14C]putrescine. 3. Exposure of beta L-crystallin to hydroxyl radicals, thymine peroxyl radicals and acetone peroxyl radicals at concentrations of up to 135 microM increased the capacity of the protein to incorporate putrescine. With higher concentrations of these radicals this capacity of beta L-crystallin to act as a transglutaminase substrate declined to control levels or lower. 4. Superoxide radicals were inactive in this regard; hydroperoxyl radicals were active only at high concentrations. 5. It has previously been suggested that changes in the crystallins that occur during aging and with cataract may be due to oxidative reactions and to transglutaminase activity. This study suggests that these phenomena may be considered together rather than separately.

SUBMITTER: Seccia M

PROVIDER: S-EPMC1149990 | biostudies-other | 1991 Mar

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Exposure of beta H-crystallin to hydroxyl radicals enhances the transglutaminase-susceptibility of its existing amine-donor and amine-acceptor sites.

Project description:beta H-crystallin was exposed to radiolytically generated hydroxyl radicals at defined radical concentrations, and its capacity to act as an amine-acceptor substrate and as an amine-donor substrate for transglutaminase were investigated. [14C]Methylamine was used as a probe for labelling amine-acceptor sites; a novel biotinylated hexapeptide was used to label amine-donor sites. The results demonstrate that both primary amine incorporation and hexapeptide incorporation by transglutaminase are considerably increased after oxidative attack on the crystallin. The identity of the labelled subunits was established, and it is shown that, in both cases, this increased incorporation is not due to the production of new substrates, but that the existing incorporation sites become more susceptible. Moreover, using the newly developed probe, we could identify, for the first time, the major crystallin subunits active as amine-donor substrates (both before and after treatment) to be beta B1-, beta A3- and beta A4-crystallin. These data support the proposal that oxidative stress and transglutaminase activity may be jointly involved in the changes found in lens crystallins with age and in the development of cataract.

| S-EPMC1134895 | biostudies-other

Carnosine scavenging of glucolipotoxic free radicals enhances insulin secretion and glucose uptake.

Project description:The worldwide prevalence of diabetes has risen to 8.5% among adults, which represents a staggering rise in prevalence from 4.7% in 1980. Whilst some treatments work by increasing insulin secretion, over time their effectiveness decreases. We aim to increase insulin secretion by developing strategies that work through mechanisms independent of current treatment options. Isolated CD1 mouse islets, INS-1 pancreatic ?-cells, or C2C12 mouse myotubes were incubated in standard tissue culture media, or media supplemented with 28?mM glucose, 200??M palmitic acid, and 200??M oleic acid as a cellular model of diabetic glucolipotoxicity. Intracellular reactive species content was assayed using 2',7'-dichlorofluorescein diacetate dye, inducible nitric oxide synthase levels determined by Western blot, 3-nitrotyrosine and 4-hydrpxnonenal both assayed by ELISA, insulin secretion quantified using ELISA or radioimmunoassay, and glucose uptake determined through 2-deoxy glucose 6 phosphate luminescence. Our data indicate that carnosine, a histidine containing dipeptide available through the diet, is an effective scavenger of each of the aforementioned reactive species. This results in doubling of insulin secretion from isolated mouse islets or INS-1 ?-cells. Crucially, carnosine also reverses glucolipotoxic inhibition of insulin secretion and enhances glucose uptake into skeletal muscle cells. Thus, carnosine, or non-hydrolysable carnosine analogs, may represent a new class of therapeutic agent to fight type 2 diabetes.

| S-EPMC5645413 | biostudies-literature

Fungus-derived hydroxyl radicals kill hepatic cells by enhancing nuclear transglutaminase.

Project description:We previously reported the importance of induced nuclear transglutaminase (TG) 2 activity, which results in hepatic cell death, in ethanol-induced liver injury. Here, we show that co-incubation of either human hepatic cells or mouse primary hepatocytes derived from wild-type but not TG2-/- mice with pathogenic fungi Candida albicans and C. glabrata, but not baker's yeast Saccharomyces cerevisiae, induced cell death in host cells by enhancing cellular, particularly nuclear, TG activity. Further pharmacological and genetic approaches demonstrated that this phenomenon was mediated partly by the production of reactive oxygen species (ROS) such as hydroxyl radicals, as detected by a fluorescent probe and electron spin resonance. A ROS scavenger, N-acetyl cysteine, blocked enhanced TG activity primarily in the nuclei and inhibited cell death. In contrast, deletion of C. glabrata nox-1, which encodes a ROS-generating enzyme, resulted in a strain that failed to induce the same phenomena. A similar induction of hepatic ROS and TG activities was observed in C. albicans-infected mice. An antioxidant corn peptide fraction inhibited these phenomena in hepatic cells. These results address the impact of ROS-generating pathogens in inducing nuclear TG2-related liver injuries, which provides novel therapeutic targets for preventing and curing alcoholic liver disease.

| S-EPMC5500562 | biostudies-literature

Autoregulation of free radicals via uncoupling protein control in pancreatic beta-cell mitochondria.

Project description:Pancreatic beta-cells sense the ambient blood-glucose concentration and secrete insulin to signal other tissues to take up glucose. Mitochondria play a key role in this response as they metabolize nutrients to produce ATP and reactive oxygen species (ROS), both of which are involved in insulin secretion signaling. Based on data available in the literature and previously developed mathematical models, we present a model of glucose-stimulated mitochondrial respiration, ATP synthesis, and ROS production and control in beta-cells. The model is consistent with a number of experimental observations reported in the literature. Most notably, it captures the nonlinear rise in the proton leak rate at high membrane potential and the increase in this leak due to uncoupling protein (UCP) activation by ROS. The functional forms used to model ROS production and UCP regulation yield insight into these mechanisms, as many details have not yet been unraveled in the experimental literature. We examine short- and long-term effects of UCP activation inhibition and changes in the mitochondrial density on mitochondrial responses to glucose. Results suggest increasing mitochondrial density while decreasing UCP activity may be an effective way to increase glucose-stimulated insulin secretion while decreasing oxidative stress.

| S-EPMC2808483 | biostudies-literature

Ultraviolet Irradiation Enhances the Microbicidal Activity of Silver Nanoparticles by Hydroxyl Radicals.

Project description:It is known that silver has microbicidal qualities; even at a low concentration, silver is active against many kinds of bacteria. Silver nanoparticles (AgNPs) have been extensively studied for a wide range of applications. Alternately, the toxicity of silver to human cells is considerably lower than that to bacteria. Recent studies have shown that AgNPs also have antiviral activity. We found that large amounts of hydroxyl radicals-highly reactive molecular species-are generated when AgNPs are irradiated with ultraviolet (UV) radiation with a wavelength of 365 nm, classified as ultraviolet A (UVA). In this study, we used electron spin resonance direct detection to confirm that UV irradiation of AgNPs produced rapid generation of hydroxyl radicals. As hydroxyl radicals are known to degrade bacteria, viruses, and some chemicals, the enhancement of the microbicidal activity of AgNPs by UV radiation could be valuable for the protection of healthcare workers and the prevention of the spread of infectious diseases.

| S-EPMC7247328 | biostudies-literature

Environmentally persistent free radicals (EPFRs)-2. Are free hydroxyl radicals generated in aqueous solutions?

Project description:A chemical spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), in conjunction with electron paramagnetic resonance (EPR) spectroscopy was employed to measure the production of hydroxyl radical (·OH) in aqueous suspensions of 5% Cu(II)O/silica (3.9% Cu) particles containing environmentally persistent free radicals (EPFRs) of 2-monochlorophenol (2-MCP). The results indicate: (1) a significant differences in accumulated DMPO-OH adducts between EPFR containing particles and non-EPFR control samples, (2) a strong correlation between the concentration of DMPO-OH adducts and EPFRs per gram of particles, and (3) a slow, constant growth of DMPO-OH concentration over a period of days in solution containing 50 μg/mL EPFRs particles + DMPO (150 mM) + reagent balanced by 200 μL phosphate buffered (pH = 7.4) saline. However, failure to form secondary radicals using standard scavengers, such as ethanol, dimethylsulfoxide, sodium formate, and sodium azide, suggests free hydroxyl radicals may not have been generated in solution. This suggests surface-bound, rather than free, hydroxyl radicals were generated by a surface catalyzed-redox cycle involving both the EPFRs and Cu(II)O. Toxicological studies clearly indicate these bound free radicals promote various types of cardiovascular and pulmonary disease normally attributed to unbound free radicals; however, the exact chemical mechanism deserves further study in light of the implication of formation of bound, rather than free, hydroxyl radicals.

| S-EPMC3236504 | biostudies-literature

Environmentally persistent free radicals (EPFRs). 3. Free versus bound hydroxyl radicals in EPFR aqueous solutions.

Project description:Additional experimental evidence is presented for in vitro generation of hydroxyl radicals because of redox cycling of environmentally persistent free radicals (EPFRs) produced after adsorption of 2-monochlorophenol at 230 °C (2-MCP-230) on copper oxide supported by silica, 5% Cu(II)O/silica (3.9% Cu). A chemical spin trapping agent, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), in conjunction with electron paramagnetic resonance (EPR) spectroscopy was employed. Experiments in spiked O(17) water have shown that ?15% of hydroxyl radicals formed as a result of redox cycling. This amount of hydroxyl radicals arises from an exogenous Fenton reaction and may stay either partially trapped on the surface of particulate matter (physisorbed or chemisorbed) or transferred into solution as free OH. Computational work confirms the highly stable nature of the DMPO-OH adduct, as an intermediate produced by interaction of DMPO with physisorbed/chemisorbed OH (at the interface of solid catalyst/solution). All reaction pathways have been supported by ab initio calculations.

| S-EPMC4140529 | biostudies-literature

Fragmentation of proteins by free radicals and its effect on their susceptibility to enzymic hydrolysis.

Project description:Defined radical species generated radiolytically were allowed to attack proteins in solution. The hydroxyl radical (OH.) in the presence of O2 degraded bovine serum albumin (BSA) to specific fragments detectable by SDS/polyacrylamide-gel electrophoresis; fragmentation was not obvious when the products were analysed by h.p.l.c. In the absence of O2 the OH. cross-linked the protein with bonds stable to SDS and reducing conditions. The superoxide (O2-.) and hydroperoxyl (HO2.) radicals were virtually inactive in these respects, as were several other peroxyl radicals. Fragmentation and cross-linking could also be observed when a mixture of biosynthetically labelled cellular proteins was used as substrate. Carbonyl and amino groups were generated during the reaction of OH. with BSA in the presence of O2. Changes in fluorescence during OH. attack in the absence of O2 revealed both loss of tryptophan and changes in conformation during OH. attack in the presence of O2. Increased susceptibility to enzymic proteolysis was observed when BSA was attacked by most radical systems, with the sole exception of O2-.. The transition-metal cations Cu2+ and Fe3+, in the presence of H2O2, could also fragment BSA. The reactions were inhibited by EDTA, or by desferal and diethylenetriaminepenta-acetic acid ('DETAPAC') respectively. The increased susceptibility to enzymic hydrolysis of radical-damaged proteins may have biological significance.

| S-EPMC1146578 | biostudies-other

Free radicals in adolescent varicocele testis.

Project description:We examine the relationship between the structure and function of the testis and the oxidative and nitrosative stress, determined by an excessive production of free radicals and/or decreased availability of antioxidant defenses, which occur in the testis of adolescents affected by varicocele. Moreover, the effects of surgical treatment on oxidative stress were provided. We conducted a PubMed and Medline search between 1980 and 2014 using "adolescent," "varicocele," "free radicals," "oxidative and nitrosative stress," "testis," and "seminiferous tubules" as keywords. Cross-references were checked in each of the studies, and relevant articles were retrieved. We conclude that increased concentration of free radicals, generated by conditions of hypoxia, hyperthermia, and hormonal dysfunction observed in adolescent affected by varicocele, can harm germ cells directly or indirectly by influencing nonspermatogenic cells and basal lamina. With regard to few available data in current literature, further clinical trials on the pre- and postoperative ROS and RNS levels together with morphological studies of the cellular component of the testis are fundamental for complete comprehension of the role played by free radicals in the pathogenesis of adolescent varicocele and could justify its pharmacological treatment with antioxidants.

| S-EPMC4279722 | biostudies-literature

Free radicals promote electrocatalytic nitrogen oxidation.

Project description:In this work, we introduce hydroxyl radicals into the electrocatalytic nitrogen oxidation reaction (NOR) for the first time. Cobalt tetroxide (Co3O4) acts not only as an electrocatalyst, but also as a nanozyme (in combination with hydrogen peroxide producing ˙OH), and can be used as a high-efficiency nitrogen oxidation reaction (NOR) electrocatalyst for environmental nitrate synthesis. Co3O4 + ˙OH shows an excellent nitrogen oxidation reaction (NOR) performance among Co3O4 catalysts in 0.1 M Na2SO4 solution. At an applied potential of 1.7 V vs. RHE, the HNO3 yield of Co3O4 + ˙OH reaches 89.35 μg h-1 mgcat -1, which is up to 7 times higher than that of Co3O4 (12.8 μg h-1 mgcat -1) and the corresponding FE is 20.4%. The TOF of Co3O4 + ˙OH at 1.7 V vs. RHE reaches 0.58 h-1, which is higher than that of Co3O4 (0.083 h-1), demonstrating that free radicals greatly enhance the intrinsic activity. Density functional theory (DFT) demonstrates that ˙OH not only can drive nitrogen adsorption, but also can decrease the energy barrier (rate-determining step) of N2 to N2OH*, thus producing great NOR activity.

| S-EPMC9930917 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data