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High activity of alpha-glycerophosphate oxidation by human placental mitochondria.

Human term placental mitochondria oxidize alpha-glycerophosphate at an unusually high rate as compared to other substrates. The apparent Km both for oxidation and alpha-glycerophosphate dehydrogenase (EC 1.1.99.5) activity of DL-alpha glycerophosphate determined in a medium containing 2mM EDTA and 5 mM MgSO4 was approx. 0.7 mM. EDTA inhibited the alpha-glycerophosphate oxidation if the later was used at low concentrations. A subsequent addition of MgSO4 or CaCl2 restored the original activity. EDTA had no effect on mitochondrial respiration at high concentration of alpha-glycerophosphate. Possible physiological role of relatively high activity of human placental mitochondrial alpha-glycerophosphate dehydrogenase is discussed.

Carbonyl Cyanide m-Chlorophenyl Hydrazone↗

Structure of the Escherichia coli K2 capsular antigen. Stereochemical configuration of the glycerophosphate and distribution of galactopyranosyl and galactofuranosyl residues.

The Escherichia coli K2 capsular antigen is known to be composed of alpha-D-galactopyranosyl(1--2)glycerophosphate and alpha-D-galactofuranosyl(1--2)glycerophosphate units which are connected by phosphodiester bonds to C-4 of the galactopyranosyl and C-5 or C-6 of the galactofuranosyl moieties. In the present study the glycerophosphates were released by two different procedures and shown to have the sn-glycero-3-phosphate stereochemical configuration. In the first, the chain was fragmented by Smith degradation to glycerophosphothreitol from which the glycerophosphate was released by alkali hydrolysis. The structure-dependent low recovery of alpha-glycerophosphate (less than 10%) initiated the development of another degradative sequence which consisted of periodate oxidation, beta elimination, hydrazinolysis, and alkaline treatment. This way, approximately 90% of the glycerophosphate was released as sn-glycero-3-phosphate. beta elimination revealed in addition that most of the galactofuranosyl residues carry the phosphodiester bond at position 5. Separation by gel permeation chromatography and analysis of the fragments obtained by beta elimination showed that pyranosidic and furanosidic galactosyl residues alternate in the same chain and suggested the sequences Galf(p)GroP-(GalpGroP)n-Galf- and -GalfGroP-(GalpGroP)n-Galf-, where n is 6, 4, and 3, respectively.

Antigens↗

Acylation of carnitine and glycerophosphate in suspensions of rat liver mitochondria at varying levels of palmitate and coenzyme A.

Rates of acylation of carnitine and glycerophosphate in suspensions of isolated rat liver mitochondria were measured at varying levels of palmitate and coenzyme A in the presence of ATP. Addition of glycerophosphate caused considerable reduction in carnitine acylation at low, but not at high palmitate levels. Glycerophosphate acylation was less reduced by added carnitine. These results can be explained by a lower Km(acyl-CoA) in glycerophosphate acylation than in carnitine acylation. High levels of free coenzyme A caused inhibition of carnitine acylation, while the inhibitory effect of glycerophosphate acylation was small. Competition between palmitate and acyl-CoA for binding sites on protein (e.g., albumine added to the mitochondrial suspensions) was indicated by stimulation of carnitine acylation by palmitate with palmityl-CoA added as substrate in the absence of ATP. Refeeding a carbohydrate-rich diet to previously fasted rats resulted in increased glycerophosphate acylation and decreased carnitine acylation in isolated liver mitochondria.

Acylation↗

On the basic structure of poly(glycerophosphate) lipoteichoic acids.

Poly(glycerophosphate) lipoteichoic acids from 24 Gram-positive bacteria of the genera Bacillus, Enterococcus, Lactobacillus, Lactococcus, Listeria, Staphylococcus, and the streptococcal pyogenic and oral group were analyzed. The 1,3-linked poly(glycerophosphate) structure was proved by analysis of glycerol and glycerophosphates after acid and alkaline hydrolysis. Using the molar ratios of glycolipid to phosphorus (A) and phosphomonoester to phosphorus after periodate oxidation followed by hydrazinolysis (B) or beta-elimination (C), we show that all lipoteichoic acids contain a single unbranched poly(glycerophosphate) chain and that the chain is uniformly phosphodiester-linked to C-6 of the nonreducing hexopyranosyl residue of the glycolipid moiety. On some chains minor phosphate-containing substituents were detected whose structure remains to be clarified. The lipoteichoic acids of enterococci and listeria strains were separated by hydrophobic interaction chromatography into glycolipid- and phosphatidylglycolipid-containing molecular species. The phosphatidylglycolipid moieties were structurally characterized after liberation from lipoteichoic acids with moist acetic acid. After periodate oxidation of lipoteichoic acids beta-elimination released both phosphatidic acid and the poly(glycerophosphate) chain. This indicates together with the sequence analysis of the released phosphatidylglycolipid that the phosphatidyl residue is located at C-6 of the reducing hexosyl residue of the glycolipid moiety and the poly(glycerophosphate) chain at C-6 of the nonreducing one. Together with earlier observations these results complete the evidence for the structural and possibly biosynthetic relationship between lipoteichoic acids and glycerophosphoglycolipids.

Carbohydrate Sequence↗

Rapid stimulation of liver palmitoyl-CoA synthetase, carnitine palmitoyltransferase and glycerophosphate acyltransferase compared to peroxisomal beta-oxidation and palmitoyl-CoA hydrolase in rats fed high-fat diets.

Key enzymes involved in oxidation and esterification of long-chain fatty acids were investigated in male rats fed different types and amounts of oil in their diet. A diet with 20% (w/w) fish oil, partially hydrogenated fish oil (PHFO) and partially hydrogenated soybean oil (PHSO) was shown to stimulate the mitochondrial and microsomal palmitoyl-CoA synthetase activity (EC 6.2.1.3) compared to soybean oil-fed animals after 1 week of feeding. Rapeseed oil had no effect. Partially hydrogenated oils in the diet resulted in significantly higher levels of mitochondrial glycerophosphate acyltransferase compared to unhydrogenated oils in the diet. Rats fed 20% (w/w) rapeseed oil had a decreased activity of this mitochondrial enzyme, whereas the microsomal glycerophosphate acyltransferase activity was stimulated to a comparable extent with 20% (w/w) rapeseed oil, fish oil or PHFO in the diet. Increasing the amount of PHFO (from 5 to 25% (w/w)) in the diet for 3 days led to increased mitochondrial and microsomal palmitoyl-CoA synthetase and microsomal glycerophosphate acyltransferase activities with 5% of this oil in the diet. The mitochondrial glycerophosphate acyltransferase was only marginally affected by increasing the oil dose. Administration of 20% (w/w) PHFO increased rapidly the mitochondrial and microsomal palmitoyl-CoA synthetase, carnitine palmitoyltransferase and microsomal glycerophosphate acyltransferase activities almost to their maximum value within 36 h. In contrast, the glycerophosphate acyltransferase and palmitoyl-CoA hydrolase (EC 3.1.2.2) activities of the mitochondrial fraction and the peroxisomal beta-oxidation reached their maximum activities after administration of the dietary oil for 6.5 days. This sequence of enzyme changes (a) is in accordance with the proposal that an increased cellular level of long-chain acyl-CoA species act as metabolic messages for induction of peroxisomal beta-oxidation and palmitoyl-CoA hydrolase, i.e., these enzymes are regulated by a substrate-induced mechanism, and (b) indicates that, with PHFO, a greater part of the activated fatty acids are directed from triacylglycerol esterification and hydrolysis towards oxidation in the mitochondria. It is also conceivable that the mitochondrial beta-oxidation is proceeding before the enhancement of peroxisomal beta-oxidation.

Acyltransferases↗

Hexose metabolism in pancreatic islets. Glucose-induced and Ca(2+)-dependent activation of FAD-glycerophosphate dehydrogenase.

A rise in extracellular D-glucose concentration causes in pancreatic islets a preferential stimulation of aerobic, relative to total, glycolysis. The possible participation in such a phenomenon of a glucose-induced and Ca(2+)-dependent activation of FAD-glycerophosphate dehydrogenase was investigated. In islet homogenates, the activity of the mitochondrial and Ca(2+)-responsive FAD-glycerophosphate dehydrogenase was about two orders of magnitude lower than that of the cytosolic and Ca(2+)-insensitive NAD-glycerophosphate dehydrogenase. In islet mitochondria, Ca2+ increased the affinity of the FAD-glycerophosphate dehydrogenase for L-glycerol 3-phosphate, but did not affect the maximal reaction velocity. In the presence of 0.1 mM-L-glycerol 3-phosphate, the Ka for Ca2+ was close to 0.1 microM. When intact islets were preincubated in the presence of both D-glucose and Ca2+, the activity of FAD-glycerophosphate dehydrogenase measured in intact mitochondria incubated in the presence of 1.2 microM-Ca2+ was higher than that recorded under the same conditions in islets preincubated in the absence of D-glucose and/or Ca2+. These findings support the view that, in islets exposed to a high concentration of D-glucose, a Ca(2+)-induced activation of mitochondrial FAD-glycerophosphate dehydrogenase favours the transfer of reducing equivalents by the glycerol phosphate shuttle, and hence accounts, in part at least, for the preferential stimulation of aerobic glycolysis.

Animals↗

The soluble alpha-glycerophosphate oxidase from Enterococcus casseliflavus. Sequence homology with the membrane-associated dehydrogenase and kinetic analysis of the recombinant enzyme.

The soluble flavoprotein alpha-glycerophosphate oxidase from Enterococcus casseliflavus catalyzes the oxidation of a "non-activated" secondary alcohol, in contrast to the flavin-dependent alpha-hydroxy- and alpha-amino acid oxidases. Surprisingly, the alpha-glycerophosphate oxidase sequence is 43% identical to that of the membrane-associated alpha-glycerophosphate dehydrogenase from Bacillus subtilis; only low levels of identity (17-22%) result from comparisons with other FAD-dependent oxidases. The recombinant alpha-glycerophosphate oxidase is fully active and stabilizes a flavin N(5)-sulfite adduct, but only small amounts of intermediate flavin semiquinone are observed during reductive titrations. Direct determination of the redox potential for the FAD/FADH2 couple yields a value of -118 mV; the protein environment raises the flavin potential by 100 mV in order to provide for a productive interaction with the reducing substrate. Steady-state kinetic analysis, using the enzyme-monitored turnover method, indicates that a ping-pong mechanism applies and also allows the determination of the corresponding kinetic constants. In addition, stopped-flow studies of the reductive half-reaction provide for the measurement of the dissociation constant for the enzyme. alpha-glycerophosphate complex and the rate constant for reduction of the enzyme flavin. These and other results demonstrate that this enzyme offers a very promising paradigm for examining the protein determinants for flavin reactivity and mechanism in the energy-yielding metabolism of alpha-glycerophosphate.

Amino Acid Sequence↗

Glycerophosphate as a phosphorus source in a defined medium for Pichia pastoris fermentation.

Pichia pastoris has emerged as a commercially important yeast for the production of a vast majority of recombinant therapeutic proteins and vaccines. The organism can be grown to very high cell densities using a defined basal salts media (BSM). However, BSM contains bi-cation or tri-cation phosphate, which precipitates out of the medium at pH above 5.5, although the optimal fermentation pH of most recombinant protein fermentation varies between 5.5 and 7.0. In this article, the application of glycerophosphates was investigated as a substitute phosphate source in an effort to eliminate precipitation. The solubility of BSM containing sodium or potassium glycerophosphates was examined before and after autoclaving at various pHs. Sodium glycerophosphate was found stable at autoclave temperature but formed complexes with coexisting magnesium and calcium ions that were insoluble above pH 7.0. Medium where sodium glycerophosphate was autoclaved separately and then added to the growth medium did not produce any precipitate up to pH 10.5. The performance of P. pastoris fermentations expressing alpha-galactosidase and ovine interferon-tau using a glycerolphosphate-based medium was found to be comparable to a conventional BSM. The results from this work demonstrate that sodium glycerophosphate can be assimilated by the P. pastoris strains and can be employed as a reliable phosphorus source for both cell growth and recombinant protein production.

Biomass↗

Effects of chronic beta-glycerophosphate administration on growth rate and serum, liver and bile lipid composition in the rat--a toxicity study.

The possible toxic effects of a high dose of orally administered disodium beta-glycerophosphate to the rat for a period of 33 weeks has been investigated. The studies revealed taht beta-glycerophosphate administration had no effect on either survival rat, body weight, hematological and liver function tests or on serum and liver lipids concentrations. All organ weights were similar in the control and experimental rats excepts for the kidneys which were significantly heavier in the beta-glycerophosphate-fed rats. The biliary phospholipids concentrations was significantly increased in the treated group as observed previously during short-term treatments. Histological examination of liver and kidneys did not reveal any pathological findings. These results suggest that long-term administration of beta-glycerophosphate did not induce any toxic manifestations. The observed hyperplasia of the kidneys was attributed to the effect of the sodium content of beta-glycerophosphate.

Animals↗

Abnormal septation and inhibition of sporulation by accumulation of L- -glycerophosphate in Bacillus subtilis mutants.

Accumulation of l-alpha-glycerophosphate, in cells of Bacillus subtilis mutants lacking the nicotinamide adenine dinucleotide-independent glycerophosphate dehydrogenase activity, suppresses both growth and sporulation. After growth has stopped, the cells slowly develop one and later more asymmetric septa that are thicker than normal prespore septa and apparently contain too much cell wall material to allow further membrane development into forespores or spores. l-Malate prevents accumulation of glycerophosphate and restores sporulation of the mutant. Glucose or gluconate cannot resotre sporulation, because they still effect glycerophosphate accumulation via de novo synthesis. If that accumulation is blocked in a double mutant, which is unable to make glycerophosphate from or to metabolize it into Embden-Meyerhof compounds, then nonsuppressing amounts of glucose or gluconate can restore sporulation.

Bacillus subtilis↗

Effects of alpha-glycerophosphate and of palmityl-coenzyme A on lipid synthesis in yeast extracts.

White, David (Ames Research Center, Moffett Field, Calif.), and Harold P. Klein. Effects of alpha-glycerophosphate and of palmityl-coenzyme A on lipid synthesis in yeast extracts. J. Bacteriol. 91:1218-1223. 1966.-The incorporation of acetate into fatty acids, but not into nonsaponifiable lipids, was stimulated by alpha-glycerophosphate in a supernatant fraction of Saccharomyces cerevisiae, obtained after centrifugation at 86,000 x g for 60 min. There was a pronounced effect at concentrations below 2 mm, but at concentrations above 5 mm alpha-glycerophosphate was relatively less stimulatory. alpha-Glycerophosphate markedly increased the percentage of esterified fatty acids among the products, and the formation of both saturated and unsaturated fatty acids was stimulated. Palmityl-coenzyme A inhibited fatty acid synthesis, affecting the formation of unsaturated acids more severely than saturated acids. In the presence of sufficient alpha-glycerophosphate to alleviate these inhibitions, palmityl-coenzyme A still reduced the formation of certain unsaturated fatty acids.

Acetates↗

Development of glycerophosphate acyltransferase in guinea pig lung mitochondria and microsomes.

Development of mitochondrial and microsomal glycerophosphate acyltransferase in the fetal guinea pig lung was investigated. Mitochondrial and microsomal enzyme activity gradually increased from 45 days to 55 days of gestation. The specific activity in the microsomal fraction (8.2 nmol/min per mg protein) then declined until term, but increased again in the 24-h newborn from 2.5 to 6.1 nmol/min per mg protein. Glycerophosphate acyltransferase activity in the mitochondrial fraction declined after 55 days (3.5 nmol/min per mg) to a minimum level at 60 days (1.8 nmol/min per mg), but increased again in the 24-h newborn (4.0 nmol/min per mg). The specific activity of both mitochondrial and microsomal enzyme declined after 24 h after birth until adult levels were attained. Glycerophosphate acyltransferase activity in mitochondria and microsomes from adult lung was 0.8 and 2.0 nmol/min per mg, respectively. Microsomal enzyme activity was consistently inhibited (over 95%) throughout gestation and adulthood by exposure to any one of several proteinases: trypsin, chymotrypsin, papain, bromelain, pronase and nagarse. Although mitochondrial enzyme activity was also inhibited by these proteinases, there was a continuous increase in proteinase-resistant glycerophosphate acyltransferase activity between 45 days of gestation and term. In contrast, adult mitochondrial enzyme activity was stimulated by all the proteinases studied. These results suggest that early in gestation, glycerophosphate acyltransferase lies more exposed on the cytoplasmic side of the mitochondrial outer membrane and as gestation progresses it becomes embedded into the phospholipid bilayer.

Acyltransferases↗

Regulation of palmitate esterification/oxidation by glucagon in isolated hepatocytes: the role of alpha-glycerophosphate concentration.

Lipolysis was measured as the disappearance of [3H]glycerol previously incorporated into triacylglycerol, diacylglycerol and phosphatidic acid. There was no effect of glucagon on the lipolysis of any of these lipids. A transient increase in cellular alpha-glycerophosphate was induced by addition of glycerol during incubation. This resulted in an immediate and temporary decrease in oxidation and increase in esterification of palmitate while the uptake of palmitate from the incubation medium was unchanged. The change in alpha-glycerophosphate was also correlated with a transient drop in acyl-CoA and acylcarnitine. The lactate/pyruvate ratio was increased by the glycerol addition, but was still elevated for some while after the transient change in alpha-glycerophosphate. Similar effects were obtained by addition of dihydroxyacetone instead of glycerol. It is concluded that fatty acid esterification/oxidation can be changed by variations in the concentration of alpha-glycerophosphate, and that glucagon acts on lipid metabolism by decreasing the level of this metabolite.

Animals↗

Effect of glycerophosphate on lithogenic bile. A new approach to treatment of cholelithiasis.

Previous studies in animals showed a twofold increase of bile-phospholipids when glycerophosphate, a precursor of phospholipids, was incorporated in chow diet. The present study evaluates the effect of short-term administration of beta-glycerophosphate on bile composition in patients with lithogenic bile. 10 patients with lithogenic bile were selected for study; 9 had cholelithiasis. Fasting hepatic and gallbladder bile before and after treatment with beta-glycerophosphate (6 g. daily for six days) was analysed for molar ratios of cholesterol (Ch.), total bile-salts (B.S.), and total phospholipids (P.L.). The molar ratios of Ch. divided by B.S. + P.L. in hepatic bile decreased in 9 of the 10 patients (P less than 0.01). Thus in all but 1 of the 10 patients the hepatic bile became less lithogenic. This observation was confirmed by plotting the molar percentages on triangular coordinates. The results suggest no change in cholesterol concentrations but an increase of phospholipid and bile-salt concentrations. The composition of the gallbladder bile did not change. These preliminary studies indicate that beta-glycerophosphate should be evaluated as a potential new therapeutic agent for dissolution of cholesterol gallstones in man.

Administration, Oral↗

The alpha-glycerophosphate cycle in Drosophila melanogaster. IV. Metabolic, ultrastructural, and adaptive consequences of alphaGpdh-l "null" mutations.

"Null" mutations previously isolated at the alphaGpdh-1 locus of Drosophila melanogaster, because of disruption of the energy-producing alpha-glycerophosphate cycle, severely restrict the flight ability and relative viability of affected individuals. Two "null" alleles, alphaGpdh-1(BO-1-4), and alphaGpdh-1(BO-1-5,) when made hemizygous with a deficiency of the alphaGpdh-1 locus, Df(2L)GdhA, were rendered homozygous by recombination with and selective elimination of the Df(2L)GdhA chromosome. After over 25 generations, a homozygous alphaGpdh-1(BO-1-4) stock regained the ability to fly despite the continued absence of measurable alphaGPDH activity. Inter se heterozygotes of three noncomplementing alphaGpdh-1 "null" alleles and the "adapted" alphaGpdh-1(BO-1-4) homozygotes were examined for metabolic enzymatic activities related to the energy-producing and pyridine nucleotide-regulating functions of the alpha-glycerophosphate cycle in Drosophila. The enzyme functions tested included glyceraldehyde-3-phosphate dehydrogenase, cytoplasmic and soluble malate dehydrogenase, lactate dehydrogenase, mitochondrial NADH oxidation, oxidative phosphorylation, and respiratory control with the substrates alpha-glycerophosphate, succinate, and pyruvate. These activities in any of the mutant genotypes in early adult life were indistinguishable from those in the wild type. There was, however, a premature deterioration and atrophy of the ultrastructural integrity of flight muscle sarcosomes observed by electron microscopy in the "null" mutants. These observations were correlated with a decrease in state 3 mitochondrial oxidation with alpha-glycerophosphate, succinate, and pyruvate, as well as with loss of respiratory control in adults as early as 2 wk after eclosion. Such observations, which normally are seen in aged dipterans, were accompanied by premature mortality of the mutant heterozygotes. The adapted alphaGpdh-1(BO-1-4) was identical with wild type in each of the aging characters with the single exception of lowered rates of mitochondrial oxidative phosphorylation.

Adaptation, Biological↗

Calcium glycerophosphate and caries: a review of the literature.

AIM: To review studies in the dental literature regarding the anti-caries mode of action of glycerophosphate with special reference to calcium glycerophosphate. The cariostatic properties of calcium glycerophosphate have been demonstrated during numerous in vivo and in vitro studies. Several mechanisms have been suggested and these include plaque-pH buffering, elevation of plaque calcium and phosphate levels and direct interaction with dental mineral. There is credible evidence that calcium glycerophosphate has the potential to reduce the progression of caries via all of these mechanisms if it is applied frequently and at a sufficiently high concentration. Reduction of plaque mass has also been proposed as a cariostatic mechanism but this seems less likely. Animal studies have shown that the calcium glycerophosphate/sodium monofluorophosphate system can have a greater anti-caries effect than sodium monofluorophosphate alone and this was subsequently confirmed in a caries clinical trial. We conclude that elevation of calcium levels in plaque is the most likely explanation and that any means of enhancing this effect has significant promise as a means to further increase in anti-caries potential of the calcium glycerophosphate/sodium monofluorophosphate system compared to sodium monofluorophosphate alone.

Animals↗

Coenzyme Q releases the inhibitory effect of free fatty acids on mitochondrial glycerophosphate dehydrogenase.

Data presented in this paper show that the size of the endogenous coenzyme Q (CoQ) pool is not a limiting factor in the activation of mitochondrial glycerophosphate-dependent respiration by exogenous CoQ(3), since successive additions of succinate and NADH to brown adipose tissue mitochondria further increase the rate of oxygen uptake. Because the inhibition of glycerophosphate-dependent respiration by oleate was eliminated by added CoQ(3), our data indicate that the activating effect of CoQ(3) is related to the release of the inhibitory effect of endogenous free fatty acids (FFA). Both the inhibitory effect of FFA and the activating effect of CoQ(3) could be demonstrated only for glycerophosphate-dependent respiration, while succinate- or NADH-dependent respiration was not affected. The presented data suggest differences between mitochondrial glycerophosphate dehydrogenase and succinate or NADH dehydrogenases in the transfer of reducing equivalents to the CoQ pool.

Adipose Tissue, Brown↗

Glycerophosphate-dependent hydrogen peroxide production by rat liver mitochondria.

We studied the extent to which hormonally-induced mitochondrial glycerophosphate dehydrogenase (mGPDH) activity contributes to the supply of reducing equivalents to the mitochondrial respiratory chain in the rat liver. The activity of glycerophosphate oxidase was compared with those of NADH oxidase and/or succinate oxidase. It was found that triiodothyronine-activated mGPDH represents almost the same capacity for the saturation of the respiratory chain as Complex II. Furthermore, the increase of mGPDH activity induced by triiodothyronine correlated with an increase of capacity for glycerophosphate-dependent hydrogen peroxide production. As a result of hormonal treatment, a 3-fold increase in glycerophosphate-dependent hydrogen peroxide production by liver mitochondria was detected by polarographic and luminometric measurements.

Animals↗