Browse
Submit Data
Databases
API
Help

Dataset Information

23 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Membrane-associated pyruvate kinase in developing guinea-pig liver.

ABSTRACT: During analysis of pyruvate kinase distribution in developing guinea-pig liver it was observed that a substantial proportion of the activity remained associated with the microsomal membrane fraction ('microsomes'). Although some of this could be removed by washing with sucrose, the majority required detergent treatment for liberation, and even then at least one-half remained attached to the microsomes. Estimates of the contribution of this fraction to total cell pyruvate kinase activity indicated that it was more than 50% of the total, and this is likely to be an underestimate because of the continued latency of the enzyme even in the presence of detergent. The susceptibility of the microsomal enzyme, whether released by detergent or sucrose washing, to inactivation by Triton X-100 suggested it to be different from the cytosolic enzyme, which was stable under such conditions. (The microsomal enzyme required the presence of additional protein, such as bovine serum albumin, to maintain stability.) This view was confirmed by DEAE-cellulose chromatography and particularly isoelectric focusing, where the microsomal enzyme was shown to consist of at least four forms, which were distinctly different from those in the cytosol. Those data and the kinetic properties of the four forms in the membrane fraction indicate that the microsomal pyruvate kinase could consist of four counterparts to the cytosolic isoenzyme forms. These results are discussed in relation to the two possible explanations for the phenomenon (not mutually exclusive): that the more hydrophobic membrane forms are precursors of the cytosolic enzyme and that they may be part of functional glycolytic pathway in the microsomes of developing liver.

SUBMITTER: Farrow SM

PROVIDER: S-EPMC1146655 | biostudies-other | 1986 Apr

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Wavelength-specific optoacoustic-induced vibrations of the guinea pig tympanic membrane.

Project description:Optoacoustic-induced vibrations of the hearing organ can potentially be used for a hearing device. To increase the efficiency of such a hearing device, the conversion of the light energy into vibration energy within each type of irradiated tissue has to be optimized. To analyze the wavelength-dependency of optoacoustic-induced vibrations within the tympanic membrane (TM), and to define the most efficient and best-suited optical stimulation parameters for a novel auditory prosthesis. Single nanosecond laser pulses, continuously tunable in a range of visible to near-infrared, were used to excite the guinea pig TM. The induced vibrations of the hearing organ were recorded at the malleus using a laser Doppler vibrometer. Our results indicate a strong wavelength-dependency of the vibration's amplitude correlating with the superposition of the absorption spectra of the different specific tissue components. We investigated the spectrum of the vibrations of the hearing organ that were induced optoacoustically within a biological membrane embedded in air, in an animal model. First applications for these results can be envisioned for the optical stimulation of the peripheral hearing organ as well as for research purposes.

| S-EPMC7934890 | biostudies-literature

A kinetic study of pig liver pyruvate kinase activated by fructose diphosphate.

Project description:The paper reports a study of the reaction between phosphoenolpyruvate, ADP and Mg(2+) catalysed by pig liver pyruvate kinase when activated by fructose diphosphate and K(+). The experimental results are consistent with two non-sequential mechanisms in which the substrates and products of the reaction are phosphoenolpyruvate, ADP, Mg(2+), pyruvate and MgATP. Pyruvate release occurs before ADP binding. Two Mg(2+) ions are involved, though the two Mg(2+)-binding sites cannot be occupied simultaneously. An isomerized enzyme complex forms before release of MgATP. Values were determined for the Michaelis constants of the reaction. Apparent MgATP inhibition constants are also given.

| S-EPMC1166314 | biostudies-other

Benchmarking predictions of allostery in liver pyruvate kinase in CAGI4.

Project description:The Critical Assessment of Genome Interpretation (CAGI) is a global community experiment to objectively assess computational methods for predicting phenotypic impacts of genomic variation. One of the 2015-2016 competitions focused on predicting the influence of mutations on the allosteric regulation of human liver pyruvate kinase. More than 30 different researchers accessed the challenge data. However, only four groups accepted the challenge. Features used for predictions ranged from evolutionary constraints, mutant site locations relative to active and effector binding sites, and computational docking outputs. Despite the range of expertise and strategies used by predictors, the best predictions were marginally greater than random for modified allostery resulting from mutations. In contrast, several groups successfully predicted which mutations severely reduced enzymatic activity. Nonetheless, poor predictions of allostery stands in stark contrast to the impression left by more than 700 PubMed entries identified using the identifiers "computational + allosteric." This contrast highlights a specialized need for new computational tools and utilization of benchmarks that focus on allosteric regulation.

| S-EPMC5561472 | biostudies-literature

In vivo transcriptomic responses to thioacetamide exposure in guinea pig liver tissue

Project description:In this study we tested the ability to predict organ injury from transcriptomic data in Hartley guinea pigs at early time points after exposure to thioacetamide (9 and 33 hours). We selected thioacetamide, a compound extensively used in animal studies for its ability to cause liver damage.

2021-03-25 | GSE169545 | GEO

Electrophysiological properties of anion exchangers in the luminal membrane of guinea pig pancreatic duct cells.

Project description:The pancreatic duct epithelium secretes the HCO3--rich pancreatic juice. The HCO3- transport across the luminal membrane has been proposed to be mediated by SLC26A Cl--HCO3- exchangers. To examine the electrophysiological properties of Cl--HCO3- exchangers, we directly measured HCO3- conductance in the luminal membrane of the interlobular pancreatic duct cells from guinea pigs using an inside-out patch-clamp technique. Intracellular HCO3- increased the HCO3- conductance with a half-maximal effective concentration value of approximately 30 mM. The selectivity sequence based on permeability ratios was SCN- (1.4)?>?Cl- (1.2)?=?gluconate (1.1)?=?I- (1.1)?=?HCO3- (1.0)?>?methanesulfonate (0.6). The sequence of the relative conductance was HCO3- (1.0)?>?SCN- (0.7)?=?I- (0.7)?>?Cl- (0.5)?=?gluconate (0.4)?>?methanesulfonate (0.2). The current dependent on intracellular HCO3- was reduced by replacement of extracellular Cl- with gluconate or by H2DIDS, an inhibitor of Cl--HCO3- exchangers. RT-PCR analysis revealed that the interlobular and main ducts expressed all SLC26A family members except Slc26a5 and Slc26a8. SLC26A1, SLC26A4, SLC26A6, and SLC26A10 were found to be localized to the luminal membrane of the guinea pig pancreatic duct by immunohistochemistry. These results demonstrate that these SLC26A Cl--HCO3- exchangers may mediate the electrogenic HCO3- transport through the luminal membrane and may be involved in pancreatic secretion in guinea pig ducts.

| S-EPMC5945753 | biostudies-literature

Regulation of gluconeogenesis and lipogenesis. The regulation of mitochondrial pyruvate metabolism in guinea-pig liver synthesizing precursors for gluconeogenesis.

Project description:1. The carboxylation of pyruvate to oxaloacetate by pyruvate carboxylase in guinea-pig liver mitochondria was determined by measuring the amount of (14)C from H(14)CO(3) (-) fixed into organic acids in the presence of pyruvate, ATP, Mg(2+) and P(i). The main products of pyruvate carboxylation were malate, fumarate and citrate. Pyruvate utilization, metabolite formation and incorporation of (14)C from H(14)CO(3) (-) into these metabolites in the presence and the absence of ATP were examined. The synthesis of phosphoenolpyruvate from pyruvate and bicarbonate is minimal during continued oxidation of pyruvate. Larger amounts of phosphoenolpyruvate are formed from alpha-oxoglutarate than from pyruvate. Addition of glutamate, alpha-oxoglutarate or fumarate did not appreciably increase formation of phosphoenolpyruvate when pyruvate was used as substrate. With alpha-oxoglutarate as substrate addition of fumarate resulted in increased formation of phosphoenolpyruvate, whereas addition of succinate inhibited phosphoenolpyruvate formation. In the presence of added oxaloacetate guinea-pig liver mitochondria synthesized phosphoenolpyruvate in amount sufficiently high to play an appreciable role in gluconeogenesis. 2. Addition of fatty acids of increasing carbon chain length caused a strong inhibition of pyruvate oxidation and phosphoenolpyruvate formation, and greatly promoted carbon dioxide fixation and malate, citrate and acetoacetate accumulation. The incorporation of (14)C from H(14)CO(3) (-), [1-(14)C]pyruvate and [2-(14)C]pyruvate into organic acids formed was examined. 3. It is concluded that guinea-pig liver pyruvate carboxylase contributes significantly to gluconeogenesis and that fatty acids and metabolites play an important role in its regulation.

| S-EPMC1187731 | biostudies-other

Gluconeogenesis by isolated guinea-pig liver parenchymal cells.

Project description:1. Guinea-pig hepatocytes were prepared by collagenase digestion of the perfused liver. 2. The highest rates of gluconeogenesis were obtained from fructose, followed by pyruvate, xylitol and lactate, glycerol and propionate in that order. Maximum rates of gluconeogenesis were attained at 6-10mm substrate. 3. An initial 15-min lag period occurred during gluconeogenesis from lactate. This lag was abolished by preincubating the cells or by preincubation plus the addition of NH(4)Cl or lysine. 4. The lactate/pyruvate and 3-hydroxybutyrate/acetoacetate ratios were increased during the lag and adjusted to values favouring rapid gluconeogenesis from lactate after 15min. 5. The data suggest that the low glucose synthesis during the lag resulted from a limitation of the glutamate-aspartate shuttle and from the unusual redox state of the NAD(+) couple prevailing during this period. 6. At 0.1mm, amino-oxyacetate, a transaminase inhibitor, decreased gluconeogenesis from lactate by 80%, but had a negligible effect on glucose production from pyruvate. Gluconeogenesis from lactate was also inhibited (20%) by 10mm-dl-3-hydroxybutyrate.

| S-EPMC1172483 | biostudies-other

Motion of tympanic membrane in guinea pig otitis media model measured by scanning laser Doppler vibrometry.

Project description:Otitis media (OM) is an inflammatory or infectious disease of the middle ear. Acute otitis media (AOM) and otitis media with effusion (OME) are the two major types of OM. However, the tympanic membrane (TM) motion differences induced by AOM and OME have not been quantified in animal models in the literature. In this study, the guinea pig AOM and OME models were created by transbullar injection of Streptococcus pneumoniae type 3 and lipopolysaccharide, respectively. To explore the effects of OM on the entire TM vibration, the measurements of full-field TM motions were performed in the AOM, OME and untreated control ears by using scanning laser Doppler vibrometry (SLDV). The results showed that both AOM and OME generally reduced the displacement peak and produced the traveling-wave-like motions at relatively low frequencies. Compared with the normal ear, OME resulted in a significant change of the TM displacement mainly in the inferior portion of the TM, and AOM significantly affected the surface motion across four quadrants. The SLDV measurements provide more insight into sound-induced TM vibration in diseased ears.

| S-EPMC5018450 | biostudies-literature

Pyruvate dehydrogenase kinase activity of pig heart pyruvate dehydrogenase (E1 component of pyruvate dehydrogenase complex).

Project description:The pyruvate dehydrogenase (E1) and acetyltransferase (E2) components of pig heart and ox kidney pyruvate dehydrogenase (PDH) complex were separated and purified. The E1 component was phosphorylated (alpha-chain) and inactivated by MgATP. Phosphorylation was mainly confined to site 1. Addition of E2 accelerated phosphorylation of all three sites in E1 alpha and inactivation of E1. On the basis of histone H1 phosphorylation, E2 is presumed to contain PDH kinase, which was removed (greater than 98%) by treatment with p-hydroxymercuriphenylsulphonate. Stimulation of ATP-dependent inactivation of E1 by E2 was independent of histone H1 kinase activity of E2. The effect of E2 is attributed to conformational change(s) induced in E1 and/or E1-associated PDH kinase. PDH kinase activity associated with E1 could not be separated from it be gel filtration or DEAE-cellulose chromatography. Subunits of PDH kinase were not detected on sodium dodecyl sulphate/polyacrylamide gels of E1 or E2, presumably because of low concentration. The activity of pig heart PDH complex was increased by E2, but not by E1, indicating that E2 is rate-limiting in the holocomplex reaction. ATP-dependent inactivation of PDH complex was accelerated by E1 or by phosphorylated E1 plus associated PDH kinase, but not by E2 plus presumed PDH kinase. It is suggested that a substantial proportion of PDH kinase may accompany E1 when PDH complex is dissociated into its component enzymes. The possibility that E1 may possess intrinsic PDH kinase activity is considered unlikely, but may not have been fully excluded.

| S-EPMC1152782 | biostudies-other

Pig liver pyruvate carboxylase. The reaction pathway for the carboxylation of pyruvate.

Project description:1. The reaction pathway for the carboxylation of pyruvate, catalysed by pig liver pyruvate carboxylase, was studied in the presence of saturating concentrations of K(+) and acetyl-CoA. 2. Free Mg(2+) binds to the enzyme in an equilibrium fashion and remains bound during all further catalytic cycles. MgATP(2-) binds next, followed by HCO(3) (-) and then pyruvate. Oxaloacetate is released before the random release, at equilibrium, of P(i) and MgADP(-). 3. This reaction pathway is compared with the double displacement (Ping Pong) mechanisms that have previously been described for pyruvate carboxylases from other sources. The reaction pathway proposed for the pig liver enzyme is superior in that it shows no kinetic inconsistencies and satisfactorily explains the low rate of the ATP[unk][(32)P]P(i) equilibrium exchange reaction. 4. Values are presented for the stability constants of the magnesium complexes of ATP, ADP, acetyl-CoA, P(i), pyruvate and oxaloacetate.

| S-EPMC1166286 | biostudies-other

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