Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Effect of a transitory ischaemia on the structure-linked latency of rat liver acid phosphatase and beta-galactosidase.

ABSTRACT: The structure-linked latency of acid phosphatase and beta-galactosidase was studied in rat liver lobes made ischaemic for 1 or 2 h and then recirculated with blood for increasing periods. Free activity of acid phosphatase and unsedimentable activity of beta-galactosidase are increased in homogenates of ischaemic livers. When ischaemia had been maintained for 1 h, the recovery of normal latency for both enzymes was observed 1 h after re-establishment of the blood flow. After a 2 h period of ischaemia, unmasked activity markedly decreases during the first 1 h after restoration of blood flow; after that, a large and irreversible secondary rise takes place. Chlorpromazine, injected 30 min before or just after induction of ischaemia, extensively prevents the latency decrease occurring during restoration of blood flow. Modifications of the hydrolase distribution pattern obtained after differential centrifugation are in agreement with the latency changes. These results suggest that a 2 h ischaemia causes an alteration of the liver lysosomes that is largely reversible and that restoration of blood flow induces an irreversible alteration of these organelles. Chlorpromazine treatment prevents the irreversible lesion from taking place.

SUBMITTER: Wattiaux R

PROVIDER: S-EPMC1163108 | biostudies-other | 1981 Jun

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Effect of mercurial compounds on structure-linked latency of lysosomal hydrolases.

Project description:1. A partially purified lysosomal preparation was obtained from adult mouse livers by sucrose-density-gradient centrifugation of a large-granule fraction. 2. This lysosome-enriched subfraction was contaminated approx. 10% by mitochondrial cytochrome c oxidase and malate dehydrogenase. 3. Free acid phosphohydrolase and beta-glucuronidase contributed less than 10% of the total (Triton X-100-solubilized) activity in contrast with approx. 30% free N-acetyl-beta-d-glucosaminidase when assayed in an iso-osmotic incubation system. 4. Exposure of the lysosomal preparation to inorganic Hg(2+) ions and organic mercurials (p-chloromercuribenzoate, phenylmercuric acetate) induced an irreversible loss of structure-linked latency with resulting enzyme activation. 5. Maximal activation was related to log [Hg(2+)] and pH. The response was all-or-none for individual particles; the dose-response curve portrayed the variation in particle resistance within the lysosomal population. 6. l-Cysteine and GSH totally prevented Hg(2+) ion-induced hydrolase activation. Ascorbate provided approx. 50% protection. 7. The three lysosomal hydrolases were differentially activated at constant [Hg(2+)], suggesting a different pattern of binding, unique for each enzyme studied.

| S-EPMC1198364 | biostudies-other

Picomolar inhibition of β-galactosidase (bovine liver) attributed to loop closure.

Project description:In an effort to examine similarities in the active sites of glycosidases within the GH35 family, we performed a structure-activity-relationship study using our recently described library of galactonoamidines. The kinetic evaluation based on UV/Vis spectroscopy disclosed inhibition of β-galactosidase (bovine liver) in the picomolar concentration range indicating significantly higher inhibitor affinity than previously determined for β-galactosidase (A. oryzae). Possible alterations in the secondary protein structure or folding were excluded after further examination of the inhibitor binding using CD spectroscopy. Molecular dynamics studies suggested loop closing interactions as a rationale for the disparity of the active sites in the β-galactosidases under investigation.

| S-EPMC5632213 | biostudies-literature

The Protective Effect of Zinc Against Liver Ischaemia Reperfusion Injury in a Rat Model of Global Ischaemia.

Project description:BackgroundIschaemia-reperfusion injury (IRI) is a major obstacle during liver transplantation and resection surgeries for cancer, with a need for effective and safe drugs to reduce IRI. Zinc preconditioning has been shown to protect against liver IRI in a partial (70%) ischaemia model. However, its efficacy against a clinically relevant Pringle manoeuvre that results in global liver ischaemia (100%) is unknown.AimsThe aim of this study was to test the efficacy of zinc preconditioning in a rat model of global liver ischaemia.MethodsRats were preconditioned via subcutaneous injection of 10 mg/kg of ZnCl2, 24 h and 4 h before ischaemia. Total liver ischaemia (100%) was induced by placing a clamp across the portal triad for 30 min. Liver injury was assessed by serum alanine transaminase (ALT) and aspartate transaminase (AST) levels in blood taken before ischaemia (baseline) and at 1, 2, 4, 24, 48, 72, 96 and 120 hours after ischaemia. Animals were culled after 7 days, and the harvested livers were histologically analysed.ResultsOn a two-way repeated-measures analysis of variance, there was a statistically significant (p = 0.025) difference in the mean ALT levels between saline- and ZnCl2-treated groups. Specifically at 24 h after ischaemia, the ALT (341 ± 99 U/L) and AST (606 ± 78 U/L) in the zinc-treated group were significantly less than the ALT (2863 ± 828 U/L) and AST (3591 ± 948 U/L) values in the saline-treated group. Zinc significantly reduced neutrophil infiltration and necrosis compared with the saline control.ConclusionZinc preconditioning reduces the overall hepatocellular damage from IRI. These results lay the foundation to assess the benefit of zinc preconditioning for clinical applications.

| S-EPMC7212296 | biostudies-literature

Stimulation of rat liver beta-galactosidase activity by ions.

Project description:1. The p-nitrophenyl beta-D-galactosidase asctivity in rat liver homogenates of lysosome-rich fractions was shown to be markedly affected by the ionic composition of the medium. A stimulation of the reaction rate at pH 5 was produced by most of the salts tested, which contained anions such as acetate, SO4(2-) and Cl-, and cations such as Na+, K= and Mg2+. The most pronounced effect was observed with MgCl2. Only potassium glutamate was inhibitory. 2. Five peaks of beta-galactosidase activity obtained by DEAE-cellulose chromatography were equally sensitive to changes in the ionic composition of the medium. In the presence of added NaC1, the whole rate-pH curve was displaced towards higher pH values, the optimum being shifted from 2.0-2.5 to 3.5. The stimulation at pH 5.0 appeared to be mainly due to changes in Vmax., whereas the apparent Km was slightly modified. 3. Unlike the total, the free beta-galactosidase activity remained unchanged or even declined when KC1 was added to the reaction medium.

| S-EPMC1172404 | biostudies-other

Structural basis of protein phosphatase 2A stable latency.

Project description:The catalytic subunit of protein phosphatase 2A (PP2Ac) is stabilized in a latent form by ?4, a regulatory protein essential for cell survival and biogenesis of all PP2A complexes. Here we report the structure of ?4 bound to the N-terminal fragment of PP2Ac. This structure suggests that ?4 binding to the full-length PP2Ac requires local unfolding near the active site, which perturbs the scaffold subunit binding site at the opposite surface via allosteric relay. These changes stabilize an inactive conformation of PP2Ac and convert oligomeric PP2A complexes to the ?4 complex upon perturbation of the active site. The PP2Ac-?4 interface is essential for cell survival and sterically hinders a PP2A ubiquitination site, important for the stability of cellular PP2Ac. Our results show that ?4 is a scavenger chaperone that binds to and stabilizes partially folded PP2Ac for stable latency, and reveal a mechanism by which ?4 regulates cell survival, and biogenesis and surveillance of PP2A holoenzymes.

| S-EPMC3644067 | biostudies-literature

An Optimized Protocol for Histochemical Detection of Senescence-associated Beta-galactosidase Activity in Cryopreserved Liver Tissue.

Project description:Senescence-associated beta-galactosidase (SA-β-gal) activity assay is commonly used to evaluate the increased beta-galactosidase (β-gal) activity in senescent cells related to enhanced lysosomal activity. Although the optimal pH for β-gal is 4.0, this enzymatic activity has been most commonly investigated at a suboptimal pH by using histochemical reaction on fresh tissue material. In the current study, we optimized a SA-β-gal activity histochemistry protocol that can also be applied on cryopreserved hepatic tissue. This protocol was developed on livers obtained from control rats and after bile duct resection (BDR). A significant increase in β-gal liver activity was observed in BDR rats vs controls after 2 hr of staining at physiological pH 4.0 (6.98 ± 1.19% of stained/total area vs 0.38 ± 0.22; p<0.01) and after overnight staining at pH 5.8 (24.09 ± 6.88 vs 0.12 ± 0.08; p<0.01). Although we noticed that β-gal activity staining decreased with cryopreservation time (from 4 to 12 months of storage at -80C; p<0.05), the enhanced staining observed in BDR compared with controls remained detectable up to 12 months after cryopreservation (p<0.01). In conclusion, we provide an optimized protocol for SA-β-gal activity histochemical detection at physiological pH 4.0 on long-term cryopreserved liver tissue.

| S-EPMC7132825 | biostudies-literature

1.8 A resolution structure of β-galactosidase with a 200 kV CRYO ARM electron microscope.

Project description:We report the determination of the structure of Escherichia coli β-galactosidase at a resolution of ∼1.8 Å using data collected on a 200 kV CRYO ARM microscope equipped with a K3 direct electron detector. The data were collected in a single 24 h session by recording images from an array of 7 × 7 holes at each stage position using the automated data collection program SerialEM. In addition to the expected features such as holes in the densities of aromatic residues, the map also shows density bumps corresponding to the locations of hydrogen atoms. The hydrogen densities are useful in assigning absolute orientations for residues such as glutamine or asparagine by removing the uncertainty in the fitting of the amide groups, and are likely to be especially relevant in the context of structure-guided drug design. These findings validate the use of electron microscopes operating at 200 kV for imaging protein complexes at atomic resolution using cryo-EM.

| S-EPMC7340270 | biostudies-literature

Crystal structure of human β-galactosidase: structural basis of Gm1 gangliosidosis and morquio B diseases.

Project description:G(M1) gangliosidosis and Morquio B are autosomal recessive lysosomal storage diseases associated with a neurodegenerative disorder or dwarfism and skeletal abnormalities, respectively. These diseases are caused by deficiencies in the lysosomal enzyme β-d-galactosidase (β-Gal), which lead to accumulations of the β-Gal substrates, G(M1) ganglioside, and keratan sulfate. β-Gal is an exoglycosidase that catalyzes the hydrolysis of terminal β-linked galactose residues. This study shows the crystal structures of human β-Gal in complex with its catalytic product galactose or with its inhibitor 1-deoxygalactonojirimycin. Human β-Gal is composed of a catalytic TIM barrel domain followed by β-domain 1 and β-domain 2. To gain structural insight into the molecular defects of β-Gal in the above diseases, the disease-causing mutations were mapped onto the three-dimensional structure. Finally, the possible causes of the diseases are discussed.

| S-EPMC3265862 | biostudies-literature

LacZ β-galactosidase: structure and function of an enzyme of historical and molecular biological importance.

Project description:This review provides an overview of the structure, function, and catalytic mechanism of lacZ β-galactosidase. The protein played a central role in Jacob and Monod's development of the operon model for the regulation of gene expression. Determination of the crystal structure made it possible to understand why deletion of certain residues toward the amino-terminus not only caused the full enzyme tetramer to dissociate into dimers but also abolished activity. It was also possible to rationalize α-complementation, in which addition to the inactive dimers of peptides containing the "missing" N-terminal residues restored catalytic activity. The enzyme is well known to signal its presence by hydrolyzing X-gal to produce a blue product. That this reaction takes place in crystals of the protein confirms that the X-ray structure represents an active conformation. Individual tetramers of β-galactosidase have been measured to catalyze 38,500 ± 900 reactions per minute. Extensive kinetic, biochemical, mutagenic, and crystallographic analyses have made it possible to develop a presumed mechanism of action. Substrate initially binds near the top of the active site but then moves deeper for reaction. The first catalytic step (called galactosylation) is a nucleophilic displacement by Glu537 to form a covalent bond with galactose. This is initiated by proton donation by Glu461. The second displacement (degalactosylation) by water or an acceptor is initiated by proton abstraction by Glu461. Both of these displacements occur via planar oxocarbenium ion-like transition states. The acceptor reaction with glucose is important for the formation of allolactose, the natural inducer of the lac operon.

| S-EPMC3575911 | biostudies-literature

ARRB1 ameliorates liver ischaemia/reperfusion injury via antagonizing TRAF6-mediated Lysine 6-linked polyubiquitination of ASK1 in hepatocytes.

Project description:Hepatic ischaemia/reperfusion (I/R) injury is a major clinical problem during liver surgical procedures, which usually lead to early transplantation failure and higher organ rejection rate, and current effective therapeutic strategies are still limited. Therefore, in-depth exploring of the molecular mechanisms underlying liver I/R injury is key to the development of new therapeutic methods. ?-arrestins are multifunctional proteins serving as important signalling scaffolds in numerous physiopathological processes, including liver-specific diseases. However, the role and underlying mechanism of ?-arrestins in hepatic I/R injury remain largely unknown. Here, we showed that only ARRB1, but not ARRB2, was down-regulated during liver I/R injury. Hepatocyte-specific overexpression of ARRB1 significantly ameliorated liver damage, as demonstrated by decreases in serum aminotransferases, hepatocellular necrosis and apoptosis, infiltrating inflammatory cells and secretion of pro-inflammatory cytokines relative to control mice, whereas experiments with ARRB1 knockout mice gotten opposite effects. Mechanistically, ARRB1 directly interacts with ASK1 in hepatocytes and inhibits its TRAF6-mediated Lysine 6-linked polyubiquitination, which then prevents the activation of ASK1 and its downstream signalling pathway during hepatic I/R injury. In addition, inhibition of ASK1 remarkably abolished the disruptive effect result from ARRB1 deficiency in liver I/R injury in vivo, indicating that ASK1 was required for ARRB1 function in hepatic I/R injury. In conclusion, we proposed that ARRB1 is a novel protective regulator during liver I/R injury, and modulation of the regulatory axis between ARRB1 and ASK1 could be a novel therapeutic strategy to prevent this pathological process.

| S-EPMC7348167 | 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