Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The high oxygen affinity of fetal blood in rabbits is due to a very low concentration of 2,3-diphosphoglycerate (2,3-DPG) in the red cells. In order to gather informations on the factors responsible for this characteristic we have studied synthesis and break-down of 2,3-DPG in fetal and adult rabbit red cells in vitro and examined possible regulative pathways which may lead to the low 2,3-DPG concentration in vivo. 2. Under conditions where 2,3-DPG and 3-phosphoglycerate (3-PGA) accumulate in adult erythrocytes, i.e. in a solution containing inosine, pyruvate and inorganic phosphate, the amount of 2,3-DPG synthetized in fetal red cells was only 40% of the adult value and 3-PGA was not measurable. Upon inhibition of enolase by NaF, however, both 2,3-DPG and 3-PGA increased to a similar extent in fetal and adult red cells. These findings point towards differences in the pyruvate kinase (PK) reaction which is one of the rate limiting steps of glycolysis. Direct measurements revealed an over tenfold higher PK activity in fetal compared to adult red cells. This higher activity of PK will lead to a decreased concentration of 3-PGA with a consecutive fall in 2,3-DPG concentration. 3. Other factors, like a decreased glucose utilization, a decreased activity of 2,3-DPG mutase or an increased 2,3-DPG phosphatase activity could be excluded as a cause for the low 2,3-DPG concentration in fetal red blood cells. The same holds for extraerythrocytic factors like glucose concentration or pH value in fetal blood. 4. During the postnatal development of rabbits the PK activity decreased. 50 days after birth, PK activity was 20% of the fetal value but still somewhat higher than in adult erythrocytes. This change is paralleled by an increase in 2,3-DPG concentration and half saturation oxygen pressure. With respect to the synthesis of 2,3-DPG and ATP, the fetal rabbit red cell is comparable to hereditary high PK activity in human erythrocytes.
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PMID:High pyruvate kinase activity causes low concentration of 2,3-diphosphoglycerate in fetal rabbit red cells. 2 78

The property of the neuronal membrane to be permeable to metabolic modifiers of two regulatory enzymes has been utilized to manipulate the spike activity of inspiratory (I) and expiratory-inspiratory (EI) neurons of the bulbar respiratory centre. The neurons have been classified according to their response to lung distention or collapse (alpha- or beta-type) and to hyperventilation (tonic firing denoted by "+", cessation of activity by "-"). Using extracellular microelectrodes for single unit recording, the medulla oblongata was superfused with a metabolite-containing CSF. The various neuronal sub-types exhibited a differential activating or inhibitory response to one or several metabolic effectors. For example Ialpha+ units were activated by 5 mM glucose-6-phosphatase (G-6-P) and 3.5 mM 3-phosphoglycerate (3-PGA), which both inhibited Ibeta+ neurons, while 5 mM AMP inhibited Ialpha+ much more strongly than Ibeta+ cells. The spike density of Ialpha- and Ibeta- neurons was increased in the presence of 2.5 mM fructose-6-phosphate and 3.5--5 mM AMP, but became reduced by G-6-P. In contrast, 3 mM fructose-1,6-diphosphate and 5 mM 3-PGA activated the Ialpha- but inhibited the Ibeta- neurons. The EIbeta units were characteristically activated by 10 mM citrate, which inhibited all I-type neurons. Activations of the Ialpha and Ibeta neurons led to an accelerated respiratory rate and a higher tidal volume, while the opposite was true for EIbeta neurons. Intravenous injection of metabolites could not duplicate the striking effects under local applications.
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PMID:Metabolic control of respiratory neuronal activity and the accompanying changes in breathing movements of the rabbit. 1. Mainpulation of inspiratory and expiratory-inspiratory neurons. 18 80

Ten tryptophan residues per one protein molecule were found to be present in the enolase from human and swine muscle. In Tris buffer, N-bromosuccinimide (NBS) inactivated the enolases after oxidation of all 10 tryptophan residues. The presence of 2-phosphoglycerate (2-PGA) partially protected the activity, and in the presence of 2-PGA together with Mg2+ full protection was observed. In phosphate buffer, only 6 tryptophan residues could be oxidized, but the enzyme was fully inactivated. 2-PGA made possible the oxidation of all 10 tryptophan residues, concomitant with full inactivation. In either case, Mg2+ had no effect. The Km values and pH optima were the same for the native and partially NBS-modified enolases.
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PMID:The reaction of N-bromosuccinimide with enolase. 61 Feb 83

It may be concluded that the conversion of PGA to DPGA plays a key role in induction and in the regulation of cycle activity. The high concentrations of PGA in actively photosynthesizing chloroplasts reflect this role and the control exerted by adenylate ratios. Thus the cycle can operate at its maximum rate only in the presence of high PGA and low ribulose 5-phosphate concentrations. Once induction is complete, the reductive pentose phosphate pathway will continue to function at its maximum rate if sink activity within the cytoplasm makes available sufficient Pi to support rapid export of triose phosphate. If triose phosphate tends to build up in the straoma, it will favor pentose monophosphate accumulation. A relative excess of ribulose 5-phosphate would, in turn, inhibit PGA reduction (and hence its own formation) by drawing too heavily on the available ATP.
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PMID:Regulation of photosynthetic carbon assimilation. 74 10

1. Incubation of rabbit choroid plexus, anterior uvea (iris-ciliary body complex) or slices of kidney cortex in a medium containing tritium-labelled prostaglandin F(2alpha) ([3H]PGF(2alpha) or E1 ([3H]PGE1) results in a four- to thirteenfold concentrative accumulation of 3H activity. 2. Addition of PGF(2alpha, PGF(1) or PGA(1), any one of five PG analogues or a PG precursor, arachidonic acid, at a concentration of 10(-4) M reduced the active accumulation of [3H]PGs by 47-97%. Octanoic acid, at the same concentration, had only a moderate effect on the choroid plexus and no significant inhibitory effect on [3H]PFG(2alpha) accumulation by anterior uvea or kidney cortex. 3. Inhibition was also obtained with 2 mM iodoacetate (under anaerobic conditions) and with 10(-4) M diploretin phosphate, probenecid, iodipamide, indomethacin or dinitrophenol. Perchlorate (10(-4) M) and iodide (10(-4) or 10(-3) M) had no inhibitory effect while 10(-4) M p-aminohippuric acid had a significant inhibitory effect on the kidney cortex at a concentration of 10(-4) M and on the anterior uvea at 10(-3) M. 4. It is concluded that the apparent carrier mediated PG transport systems of the choroid plexus, anterior uvea and kidney cortex are not related to the iodide transport system, but may represent a subcomponent of the iodipamide transport system of these tissues. 5. These results suggest that the systemic distribution and the rate of renal excretion of PGs could be altered by high concentrations of PGs, pharmacologically less active PG analogues, some inhibitors of organic acid transport, and by some inhibitors of PG synthesis and PG action.
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PMID:Inhibition of in vitro concentrative prostaglandin accumulation by prostaglandins, prostaglandin analogues and by some inhibitors of organic anion transport. 93 72

Fermentation parameters for the production of penicillin G acylase by Escherichia coli NCIM 2400 have been evaluated. The bacterium produced the enzyme intracellularly when grown in nutrient broth containing PAA. PAA stimulated the enzyme synthesis by 8-10 fold and reduced the lag period. The optimum concentration of PAA for induction was 20 mM and addition of PAA prior to inoculation gave maximum production of PGA. Glucose, lactose, sorbitol, acetate and lactate even at 0.1% concentration catabolically repressed the enzyme formation. Peptone was the best utilised 'N' source for the enzyme production. Phosphate and yeast extract were found to be essential for both the growth and for enzyme biosynthesis. Temperature between 22-24 degrees C was optimum and under ideal condition E. coli NCIM 2400 produced 0.45-0.55 U/ml of penicillin G acylase.
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PMID:Biosynthesis of benzylpenicillin acylase by Escherichia coli NCIM-2400. 269 12

The Langmuir affinity constant and adsorptive capacity for the adsorption of citrate anion or cholate anion by colestipol hydrochloride at pH 7.5, 37 degrees C, were similar. Prior exposure of colestipol hydrochloride to citrate anion caused the adsorption of cholate anion to decrease slightly in comparison to a control utilizing only cholate anion. The concentration of citrate anion was found to be directly related to the decrease in cholate anion adsorption. Simultaneous exposure of colestipol hydrochloride to citrate and cholate anions at pH 7.5, 37 degrees C, resulted in the same adsorption of cholate anion as sequential exposure to citrate anion followed by cholate anion. Sequential exposure of colestipol hydrochloride to simulated gastric fluid and simulated intestinal fluid containing cholate anion resulted in a small decrease in cholate adsorption which was attributed to competition with phosphate anion in simulated intestinal fluid. Pepsin in the simulated gastric fluid did not affect adsorption of cholate anion from simulated intestinal fluid. Preexposure to components of tomato juice and orange juice also slightly reduced the adsorption of cholate anion by colestipol hydrochloride.
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PMID:Effect of anions on adsorption of bile salts by colestipol hydrochloride. 281 76

The purpose of this research was to examine the effect of annealing treatments on the mechanical properties of polyglycolic acid sutures, and their subsequent influence on PGA degradation properties. An attempt was made to develop a better understanding of the degradation mechanism of synthetic absorbable sutures, including the relationship of their structure, morphology, and mechanical properties. PGA sutures were annealed under selected axial strain (freely hung, 0%, 1%, 10%), at four temperatures (150 degrees C, 170 degrees C, 180 degrees C, 190 degrees C), and two times (5 and 20 min). The annealed PGA specimens were then subjected to hydrolysis in phosphate-buffer solutions (pH = 7.4) for up to 28 days at 37 degrees C. Tensile properties were used to evaluate the effect of annealing treatments. The data were subjected to statistical analysis using the SAS system. All of the one-, and many of the two- and three-factor interactions were found to be statistically significant. Annealing treatments did alter the mechanical properties of PGA sutures, as well as their degradation properties. Except for the increase in tenacity of samples with increasing percent extension, all other respects of the annealing treatments resulted in lower tenacity and breaking elongation when compared with the control samples. Sutures that have been exposed to any level of axial tension during annealing, however, exhibited a lower rate of hydrolytic degradation than the freely hung suture samples. The reduction of the characteristics of fiber structure due to the tendency of the tie-chain molecules to acquire the less constrained conformations and thus to bring the crystal blocks they connect back to the original arrangement before drawing is believed to be responsible for the freely hung specimens to behave quite differently from the clamped and stressed PGA samples.
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PMID:The effect of annealing treatments on the tensile properties and hydrolytic degradative properties of polyglycolic acid sutures. 301 8

Pepsin-solubilized bovine dermal collagen was reconstituted in 0.02 M sodium phosphate (pH 7.2), concentrated to 30-40 mg/ml, and adjusted to physiological ionic strength by addition of sodium chloride. These preparations, at 4-15 degrees C, are fibrillar suspensions composed of fibrils of varying diameters and nonassociated molecules. Addition of heparin to these suspensions promoted a dose-dependent increase in average fibril diameter as measured by turbidimetry and electron microscopic analyses. These effects were relatively specific for heparin and heparin-like glycosaminoglycans. Chondroitin sulfate and hyaluronic acid had little or no effect on fibrillar diameters under these conditions, whereas dermatan sulfate had an intermediate effect on fibrillar reorganization. Differential scanning calorimetry revealed that addition of optimal concentrations of heparin generated fibrils of higher stability and that this effect was associated with the disappearance of structures of lower stability, including nonassociated molecules and thin fibrils. Light microscopic analyses of the fibrillar collagen/heparin matrix showed it to be a more open network of distinct collagen fibers than was observed with the fibrillar collagen preparation alone. Binding experiments indicated that heparin bound to fibrillar collagen in a saturable fashion with a Kd of approximately 4 X 10(-7) M. Creep experiments provided evidence that the addition of heparin to fibrillar collagen suspensions greatly reduces the gelation phenomenon that is normally observed when such suspensions are warmed to 37 degrees C. These differences in fibrillar architecture may be in part responsible for differences noted in the biological response to fibrillar collagen and fibrillar collagen/heparin implants in vivo (McPherson et al., 1988).
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PMID:The effects of heparin on the physicochemical properties of reconstituted collagen. 312 21

We have studied the effects of 2,3-diphosphoglycerate (2,3-DPG), 3-phosphoglycerate (3-PG), 3-phosphoglyceraldehyde (3-PGA), 2-phosphoglycerate (2-PG) and beta-glycerol phosphate (beta-GP) on platelet aggregation and on thromboxane B2 (TXB2) formation. The results show that 2,3-DPG, 3-PG, and 3-PGA inhibited platelet aggregation and TXB2 formation induced by norepinephrine, ADP, epinephrine, and collagen; but they also induced platelet aggregation and TXB2 formation in the presence of subthreshold concentrations of Na arachidonate. 2-PG and beta-GP were inactive. The results also show that there is a structure-function relationship between 2,3-DPG, 3-PG, and 3-PGA with platelet aggregation phenomena and prostaglandin synthesis.
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PMID:Structure-function relationship of 3-phosphoglycerate analogues with platelet aggregation and thromboxane A2 formation. 359 60


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