PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “GLYCEROPHOSPHATES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed1982

Characterization of reconstituted partially purified glycerophosphate acyltansferase from Escherichia coli.

A modification of the method of Snider and Kennedy (J. Bacteriol. (1977) 130, 1072-1083) was worked out to solubilize sn-glycero-3-phosphate acyltransferase from whole cells by Triton X-100. The solubilized preparation was used for a systematic study of the reconstitution of enzymatic activity as observed by addition of phospholipid vesicles. Although enzymatic activity was regained by addition of vesicles and not by addition of multilayered liposomes, subsequent Sepharose 4B chromatography revealed the enzyme to be incorporated in large lipid aggregates of undefined structures. Incorporation of glycerophosphate acyltransferase in single bilayer vesicles composed of phosphatidylcholine and phosphatidylglycerol (4:1) was obtained after removal to Triton X-100 from the enzyme solution, co-dispersion of enzyme and phospholipids with cholate and Sephadex G-50 gel filtration of this mixture to remove cholate. The optimal conditions for this reconstitution procedure with respect to phospholipid/protein and phosphatidylcholine/phosphatidylglycerol ratio were established. The active site of glycero-3-phosphate acyltransferase in the reconstituted system was localized for at least 90% at the outside surface of the vesicle, as revealed by proteolysis experiments under conditions of vesicle intactness as shown by C-NMR experiments. The reconstituted systems produced only lysophosphatidate from sn-[14C]glycero-3-phosphate and palmitoyl-CoA and showed identical apparent Km for sn-glycero-3-phosphate and identical pH- and temperature-dependencies as the enzyme in isolated Escherichia coli membranes.

Acyltransferases↗
PubMed1994

Effects of dietary fatty acid composition on glycerophosphate acyltransferase activity in rat adipose tissue and liver.

1. How source of dietary fat influences glycerophosphate acyltransferase (GPAT) activity in homogenates of adipose tissue and liver was determined using 5 rats per diet that contained 12% fat from either corn- (CO), high-oleate-safflower (HOSO), palm- or high-stearate-oils. 2. Activity was greatest in adipose tissue homogenates of rats fed HOSO and CO whereas no treatment effects were observed in liver homogenates. 3. No differences in fat pad weights were observed; thus HOSO- and CO-diets likely depressed other lipid synthetic rates. 4. Data indicate that mono- and diunsaturated fatty acid diets supported greater adipose tissue GPAT activity than did saturated fat diets when fed to rats.

Adipose Tissue↗
PubMed1993

Expression of alpha-glycerophosphate dehydrogenase during the development and aging of malaria vector Anopheles stephensi (Diptera: Culicidae).

alpha-Glycerophosphate dehydrogenase (GPDH) expression during the complete development and aging of Anopheles stephensi has been studied by electrophoretic and spectrophotometric techniques. Single gene locus seems to govern the developmental expression of three isozymes numbered from GPDH-1 to GPDH-3 in order of decreasing mobility. GPDH-3 was present in all the stages of development. GPDH-1 disappeared during senescence. GPDH-2, the band of intermediate mobility, was adult specific. GPDH-1 has been indicated to be more suitable for energy metabolism and GPDH-3 for lipid biosynthesis. Three codominant alleles control the four electrophoretic variants revealed in the laboratory strain. Quantitatively, the activity of GPDH continuously increased during development and showed its peak on day-4 adults of both sexes. However, the activity decreased during senescence. Tissue and sex specific differences in isozymes pattern have also been analysed. Changes in isozymes and specific activity have been correlated with the various physiological and morphological events occurring during development.

Animals↗
PubMed1996

FAD-glycerophosphate dehydrogenase activity in lymphocytes of type-2 diabetic patients and their relatives.

The activities of FAD-linked glycerophosphate dehydrogenase (m-GDH), glutamate dehydrogenase (GlDH), glutamate-pyruvate transaminase (GPT) and glutamate-oxalacetate transaminase (GOT) were measured in purified populations of CD3+ lymphocytes from 55 control subjects, 62 type-2 diabetics and 50 non-diabetic relatives of the latter patients. The activity of m-GDH was measured by both a radioisotopic procedure and colourimetric technique. As judged from these measurements and relative to the paired value for GlDH, the incidence of abnormally low m-GDH activity was significantly higher in type-2 diabetics than in control subjects. Moreover, the paired ratio in reaction velocity between the colourimetric and radioisotopic assay of m-GDH was abnormally high in patients with low m-GDH activity. Low m-GDH activity often coincided with increased GPT activity in plasma or high GPT/GOT ratio in lymphocytes. No obvious clustering of these anomalies was found in relatives of diabetic patients. These findings suggest that an inherited or acquired genomic defect of m-GDH in lymphocytes, and possibly in pancreatic B-cells, may participate to the pathogenesis of non-insulin-dependent diabetes mellitus.

Adult↗
PubMed1978

Mitochondrial alpha-glycerophosphate dehydrogenase activity in active and torpid ground squirrels, Spermophilus richardsoni.

1. Mitochondrial alpha-glycerophosphate dehydrogenase (GPD) activity was assayed in liver homogenates from active and torpid ground squirrels. 2. Arrhenius plots of GPD activity were linear in non-hibernating animals and discontinuous in hibernators. Compared with non-hibernators, the energy of activation in hibernators was reduced between 37 and 25 degrees C, but increased between 25 and 6 degrees C. 3. A dose-response relation between GPD activity and injected thyroxine was determined in active animals. No correlation was found between enzyme activity at 37 or 6 degrees C and circulating titres of thyroid hormones, in ground squirrels sampled during the preparative and hibernating phases.

Animals↗
PubMed1987

Seasonal changes in hepatic activity of G-6-phosphate and alpha-glycerophosphate dehydrogenase in farmed polecats and raccoon dogs.

Liver weight of both male and female polecats was significantly higher in winter than in summer. There were no seasonal or sex differences in the liver weight of raccoon dogs. Body weight of male polecats was highest in winter. No marked seasonal changes in body weight of female polecats, or raccoon dogs of both sexes were found. Total hepatic glucose-6-phosphate dehydrogenase activity of polecats and raccoon dogs was higher in winter than in summer. Specific activity of alpha-glycerophosphate dehydrogenase was highest in summer, but total hepatic activity did not show any seasonal changes.

Adipose Tissue↗
PubMed1990

A mutant of Mycoplasma mycoides subsp. mycoides lacking the H2O2- producing enzyme L-alpha-glycerophosphate oxidase.

Cells of Mycoplasma mycoides subsp. mycoides grown without stirring or aeration in batch culture, and resuspended in a salts solution, oxidised a range of carbohydrates including glycerol. The rate of glycerol oxidation was not reduced when cells were passaged more than 20 times in batch culture. However, in cells grown in stirred and aerated chemostat culture for 100 generations the ability to oxidise glycerol, but not other carbohydrates, was lost or greatly reduced. A mutant strain isolated from chemostat even after several passages in batch culture. The growth rate and growth-yield of the mutant strain in batch culture were similar to those of the parent strain. The mutant possessed activity for glycerol kinase but had lost that for the hydrogen peroxide-producing enzyme, L-alpha-glycerophosphate oxidase. The selection pressure in favour of the mutant strain in chemostat culture may be a decreased production of hydrogen peroxide.

Culture Media↗
PubMed2005

Time-course of hormonal induction of mitochondrial glycerophosphate dehydrogenase biogenesis in rat liver.

Thyroid hormones are important regulators of mitochondrial metabolism. Due to their complex mechanism of action, the timescale of different responses varies from minutes to days. In this work, we studied selective T3 induction of the inner mitochondrial membrane enzyme-glycerophosphate dehydrogenase (mGPDH) in liver of euthyroid rats. We correlated the kinetics of the T3 level in blood, the mRNA level in liver, the activity and amount of mGPDH in liver mitochondria after a single dose of T3. The T3 level reached maximum after 1 h (80 nmol/l) and subsequently rapidly decreased. mGPDH mRNA increased also relatively fast, reaching a maximum after 12 h and fell to the control level after 72 h. An increase of mGPDH activity could be already found after 6 h and reached a maximum after 24 h in accordance with the increase in mGPDH content (2.4-fold vs. 2.7-fold induction). After 72 h, the mGPDH activity showed a significant 30% decrease. When the rats received three subsequent doses of T3, the increase of mGPDH activity was 2-fold higher than after a single T3 dose. The results demonstrate that mGPDH displays rapid induction as well as decay upon disappearance of a hormonal stimulus, indicating a rather short half-life of this inner mitochondrial membrane enzyme.

Animals↗
PubMed1996

Stimulation of phospholipid synthesis in HeLa cells by epidermal growth factor and insulin: activation of choline kinase and glycerophosphate acyltransferase.

The cultivation of HeLa cells in the absence of growth factors reduced proliferation with a considerable decrease in the phospholipid content. A single addition of EGF or insulin was not enough to stimulate proliferation, but still sufficient to efficiently restore the phospholipid content to the level of serum-grown cells. Both EGF and insulin stimulated the synthesis of major phospholipids in HeLa cells. Irrespective of whether cells were stimulated or not, the phospholipid composition and the phospholipid/protein ratio remained constant, suggesting the existence of a mechanism that keeps them constant under varying conditions. The degradation of phosphatidylcholine was not affected by EGF or insulin. Both EGF and insulin increased choline kinase activity equally and promoted the conversion of choline to cholinephosphate, accompanied by an expansion of the cholinephosphate pool in treated cells. The level of glycerophosphate acyltransferase was enhanced by EGF and insulin but EGF was more effective than insulin. The present results provide evidence that one of the roles of EGF and insulin during cell growth is to stimulate the synthesis of phospholipids.

Choline↗
PubMed2002

Casein kinase II stimulates rat liver mitochondrial glycerophosphate acyltransferase activity.

Rat liver mitochondrial glycerophosphate acyltransferase (mtGAT) possesses 14 consensus sites for casein kinase II (CKII) phosphorylation. To study the functional relevance of phosphorylation to the activity of mtGAT, we treated isolated rat liver mitochondria with CKII and found that CKII stimulated mtGAT activity approximately 2-fold. Protein phosphatase-lambda treatment reversed the stimulation of mtGAT by CKII. Labeling of both solubilized and non-solubilized mitochondria with CKII and [gamma-32P]ATP resulted in a 32P-labeled protein of 85kDa, the molecular weight of mtGAT. Our findings suggest that CKII stimulates mtGAT activity by phosphorylation of the acyltransferase. The significance of this observation with respect to hormonal control of the enzyme is discussed.

Adenosine Triphosphate↗
PubMed1991

A lysophosphatidic acid-binding cytosolic protein stimulates mitochondrial glycerophosphate acyltransferase.

Rat liver cytosolic fraction caused up to five fold stimulation of mitochondrial glycerophosphate acyltransferase apparently by removing the lysophosphatidic acid formed by the acyltransferase. When mitochondria were incubated with palmityl-CoA, [2-3H]-sn-glycerol 3-phosphate and the cytosolic fraction and the supernatant fluid of the incubated mixture was passed through a Sephadex G-100 column, labeled lysophosphatidic acid eluted in three peaks with Mrs (i) 60-70 kDa, (ii) 10-20 kDa, and (iii) less than 5 kDa. Proteins, responsible for binding of lysophosphatidic acid in peaks (i) and (ii), were purified to near homogeneity as judged by electrophoretic analysis. The lysophosphatidic acid binding protein in peak (i) appears to be serum albumin and peak (iii) represents largely unbound lysophosphatidic acid. The 15 kDa protein, purified from peak (ii), bound lysophosphatidic acid, stimulated the acyltransferase and export of lysophosphatidic acid from mitochondria.

Animals↗
PubMed1994

Enzyme activity patterns of myosin ATPase, alpha-glycerophosphate dehydrogenase and succinate dehydrogenase within different muscle fibre types.

Muscle fibre compositions of five different rabbit muscles were determined by combining two enzyme-histochemical reactions (NADH tetracolium oxidoreductase and myosin ATPase after alkaline preincubation). The differentiation into the fibre types, fast twitch glycolytic (FTG), fast twitch oxidative (FTO), and slow twitch oxidative (STO) was possible by a reliable staining classification. Aim of the study was the estimation of enzyme activity patterns within the three different fibre types. For this purpose, four serial cross-sections with several enzyme histochemical reactions were performed: alkaline combination method for fibre type determination, the reactions of myosin ATPase, alpha-glycerophosphate dehydrogenase (GPDH), and succinate dehydrogenase (SDH). The measurement procedure for the estimation of enzyme activities was based on the proportionality between the intensity of the enzyme histochemical staining reaction and the degree of enzyme activity. The activities of GPDH (indicator for glycolytic metabolism) and SDH (oxidative metabolism) were inverse. The calcium-activated myosin ATPase showed only little activity in slow twitch fibres after alkaline preincubation. In contrast to slow twitch fibres, ATPase activity in fast twitch fibres was relatively high. The results showed that the classification of muscle fibre types due to their myosin ATPase activities and their main metabolisms (oxidative and glycolytic respectively) is justified.

Animals↗
PubMed1982

Topographic and quantitative characteristics of glutamate dehydrogenase of the hippocampus formation during the postnatal development of the rat brain. Comparative studies on succinate and alpha-glycerophosphate dehydrogenase with special reference to putatively glutamatergic structures.

As topochemically demonstrated, glutamate dehydrogenase is present within the dendritic layers of the rat hippocampus formation. Its activity increased in parallel to the postnatal maturation of synaptic structures. The results point to a contribution of glutamate dehydrogenase in the synthesis of transmitter glutamate. concomitantly, the activity of succinate and alpha-glycerophosphate dehydrogenase increased in the hippocampal dendritic areas during the postnatal development which is discussed expressing of metabolic activity. The results of the formazan elution technique reflect the topochemical findings in a quantitative manner.

Animals↗
PubMed1997

Autoantibodies against mitochondrial glycerophosphate dehydrogenase in patients with IDDM.

The mitochondrial enzyme FAD-linked glycerophosphate dehydrogenase (mGDH) plays a key role in the recognition of D-glucose as a stimulus for insulin release from the pancreatic islet B-cell. This study reveals that autoantibodies against this enzyme are not uncommonly found in patients with insulin-dependent diabetes mellitus (IDDM) examined at the onset of the disease. Antibodies reacting with a recombinant mGDH fragment product were observed in the serum of four out of 15 type-1 diabetics, but in none of 15 control subjects. The serum of patients positive for the recombinant mGDH fragment also recognized native mGDH in a rat testis extract, provided that the enzymatic protein was first exposed to an anti-mGDH rabbit serum. Antibodies against mGDH were also found in four out 12 patients with autoimmune thyroiditis. These findings reveal that a mitochondrial enzyme, that represents an essential component of the islet B-cell glucose-sensing device, may act as an antigenic determinant in patients with IDDM or other autoimmune diseases.

Adolescent↗
PubMed2000

Vitamin B12-induced alterations in activities of alpha-glycerophosphate dehydrogenase and malic enzyme in brain of singi fish, Heteropneustes fossilis (Bloch).

Different doses of vitamin B12 (0.25, 0.5, 1, 2 and 4 micrograms/g, injected intraperitoneally for three consecutive days) altered the activities of mitochondrial-alpha-glycerophosphate dehydrogenase (alpha-GPD) and NADP-dependent cytosolic malic enzyme (ME) in the brain of singi fish. The alpha-GPD activity increased at doses of 0.5, 1, 2 and 4 micrograms/g vitamin B12. A dose of 0.5 microgram/g vitamin B12 induced less activity than higher doses. ME activity increased with 1, 2 and 4 micrograms/g of vitamin B12/g. The mitochondrial and cytosolic protein content remained unchanged after vitamin B12 administration. Cycloheximide treatment inhibited the vitamin B12-induced increase in alpha-GPD and ME activity. Thus, vitamin B12 is involved in the induction of some enzymes in fish brain.

Animals↗
PubMed1979

Tri-iodothyronine-induced increase in rat liver nuclear thyroid-hormone receptors associated with increased mitochondrial alpha-glycerophosphate dehydrogenase activity.

The effect of tri-iodothyronine injection on the nuclear tri-iodothyronine receptor (putative thyroid-hormone receptor) was examined in rat liver. Nuclear receptors were extracted from isolated nuclei with 0.4 M-KCl, and their association constants (Ka) and maximal binding capacities (Cmax.) were determined by Scatchard analyses with and without correction for the endogenous hormone. The amount of endogenous tri-iodothyronine bound to non-histone protein was estimated on the basis of the specific radio-activity of [125I]tri-iodothyronine injected 2 h before the rats were killed. It was demonstrated that Cmax. of the nuclear receptors was 2.5-fold higher in severely hyperthyroid than in hypothyroid rats. However, irrespective of the thyroid status, the Ka of the receptors remained unchanged when corrected for endogenous tri-iodothyronine bound to non-histone protein. The validity of the correction was supported by experiments in vitro in which nuclear receptors were preincubated with unlabelled tri-iodothyronine. The increase in Cmax. of nuclear receptors was directly related to mitochondrial alpha-glycerophosphate dehydrogenase activity. These results suggest a hormonal modulation of the nuclear receptors which is associated with hormonal action.

Animals↗
PubMed1983

Thyroxine action on the rat liver nuclear thyroid-hormone receptors. Binding of thyroxine to the nuclear non-histone protein and induction of mitochondrial alpha-glycerophosphate dehydrogenase activity.

The possibility that thyroxine (T4) itself exerts the hormonal effect in vivo on the rat liver nuclear receptor was studied with the aid of iopanoic acid (IOP), an inhibitor of the conversion of T4 into tri-iodothyronine (T3). After administration of 2.4 micrograms of T4/100 g body weight to hypothyroid rats for 7 days, T4 and T3 concentrations in serum and in the liver nuclear non-histone protein (NHP) were all increased to the hyperthyroid range. Hepatic mitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD) activity and DNA content increased significantly. The equilibrium association constant (Ka) of the nuclear T3 receptor was unchanged and the maximal binding capacity (Cmax.) increased 1.4-fold. Simultaneous administration of IOP (5 mg/100 g body weight) to the rats given 2.4 micrograms of T4/100 g body weight completely blocked the conversion into T3. The serum T4 was even more increased, whereas the serum T3 decreased to the hypothyroid range. Although the NHP-bound T4 was at a concentration comparable with the rats given T4 alone, no NHP-bound T3 was detected. Yet the alpha-GPD activity was elevated 2.8-fold and the DNA content increased to the same extent as observed in the rats given T4 alone. The Ka and Cmax. of the nuclear receptor were significantly decreased. After administration of 48 or 480 micrograms of T4/100 g body weight for 3 days, serum T4 and T3 were markedly increased. The NHP-bound T3 was also increased, but no NHP-bound T4 was detected. The alpha-GPD activity was markedly elevated, but the DNA content was unchanged. The Cmax. per g of liver was increased, whereas the Ka remained unchanged. Simultaneous administration of IOP to these animals could not completely block the T4 conversion. The observed hormonal effects in the absence of nuclear T3 indicate that T4 possesses the intrinsic hormonal activities on the rat liver. T4 is less potent in induction of alpha-GPD activity but as potent in increment of hepatic DNA as T3. Although the binding site for T4 is not fully characterized, it appears to be acidic NHP. T4 is an active hormone, yet is also a prohormone of T3, offering the closest analogy with testosterone.

Animals↗