scholarly journals Glutamine metabolism in the gastrointestinal tract of the rat assessed by the relative activities of glutaminase (EC 3.5.1.2) and glutamine synthetase (EC 6.3.1.2)

1998 ◽  
Vol 79 (4) ◽  
pp. 365-372 ◽  
Author(s):  
L. A. James ◽  
P. G. Lunn ◽  
M. Elia
Keyword(s):  
Small Intestine ◽  
Glutamine Synthetase ◽  
Complete Information ◽  
Total Activity ◽  
External Source ◽  
Glutamine Metabolism ◽  
Gi Tract ◽  
Glutamine Synthesis ◽  
Low Levels ◽  
Glutaminase Activity

The activities of the two key enzymes involved in glutamine metabolism, glutaminase (EC 3.5.1.2) and glutamine synthetase (EC 6.3.1.2), have been measured in the various tissues of the gastrointestinal (GI) tract of the rat, from the mouth to the rectum. Glutaminase activity was particularly high in the mucosa of the small intestine, where its activity accounted for more than 80% of the total activity of the GI tract. In contrast, the mouth and oesophagus had very low activities, accounting for less than 2% of the total. Glutamine synthetase was mainly confined to the lower part of the stomach, which accounted for almost 90% of the total activity of the GI tract. Activity in the small intestine was very low, accounting for less than 2% of the total, and similarly low levels were found in the mouth and oesophagus. The data provide the most complete information on the distribution of these enzymes in the GI tract of the rat and suggest: (a) that the mucosa of the small intestine has the highest capacity for glutamine breakdown but the lowest capacity for its synthesis, and so requires an external source of this amino acid; (b) that there is little potential for glutamine synthesis or breakdown in the mouth and oesophagus; and (c) that the lower stomach has a substantial capacity to synthesize glutamine, in contrast to the rest of the GI tract. The results of the investigation are relevant to sites of glutamine metabolism in therapeutic studies involving glutamine administration discussed with reference to reports of the effects of glutamine administration on GI tract injury.

scholarly journals The regulation of phosphate-activated glutaminase activity and glutamine metabolism in the streptozotocin-diabetic rat

1984 ◽  
Vol 224 (1) ◽  
pp. 207-214 ◽  
Author(s):  
M Watford ◽  
E M Smith ◽  
E J Erbelding
Keyword(s):  
Drinking Water ◽  
Small Intestine ◽  
Glutamine Metabolism ◽  
Diabetic Rat ◽  
Complete Suppression ◽  
Chemically Induced ◽  
Phosphate Activated Glutaminase ◽  
Kidney Liver ◽  
Nh4cl Solution ◽  
Glutaminase Activity

The activity of phosphate-activated glutaminase was increased in the kidney, liver and small intestine of rats made diabetic for 6 days with injection of streptozotocin (75 mg/kg body wt.). Insulin prevented this increase in all three tissues. Treatment with NaHCO3, to correct the acidosis that accompanies diabetes, prevented the increase in renal glutaminase activity, but not that in liver or small intestine. Chemically induced acidosis (NH4Cl solution as drinking water) or alkalosis (NaHCO3 solution as drinking water) increased and decreased, respectively, glutaminase activity in the kidney, but were without significant effect on the activity in liver and small intestine. The increase in glutaminase activity in the small intestine during diabetes was due to an overall increase in the size of this organ, and was only detectable when activity was expressed in terms of whole organ, not mucosal scrapings or isolated enterocytes. Prolonged diabetes (40 days) resulted in an even greater increase in the size and glutaminase activity of the small intestine. Despite this marked increase in capacity for glutamine catabolism, arteriovenous-difference measurements showed a complete suppression of plasma glutamine utilization by the small intestine during diabetes, confirming the report by Brosnan, Man, Hall, Colbourne & Brosnan [(1983) Am. J. Physiol. 235, E261-E265].

Glutamate and glutamine metabolism in the ovine placenta

1983 ◽  
Vol 101 (2) ◽  
pp. 275-281 ◽  
Author(s):  
Jennifer M. Pell ◽  
Marjorie K. Jeacock ◽  
D. A. L. Shepherd
Keyword(s):  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Placental Transfer ◽  
Umbilical Vein ◽  
Maternal Blood ◽  
Glutamine Metabolism ◽  
Arterial Blood ◽  
Foetal Circulation ◽  
Glutamine Synthesis ◽  
Glutamyl Transferase

SUMMARYThe concentration of glutamate and of glutamine was measured in whole blood obtained from a maternal artery, a uterine vein, a foetal artery and an umbilical vein of chronically catherized ewes and foetuses from 100 to 140 days after conception. The activities of glutamate dehydrogenase, phosphate-dependent glutaminase, phosphateindependent glutaminase, glutamine synthetase, γ-glutamyl transferase and glutamine-oxo-acid aminotransferase were measured in placentomes obtained from ewes during a similar period of gestation.The concentrations of glutamate in blood from maternal vessels remained constant, whereas there was a significant decline (P < 0·001) in the concentration of glutamate in foetal blood. Glutamine concentrations declined significantly (P < 0·05) in maternal blood and in foetal arterial blood (P < 0·001), whereas the concentration of glutamine in umbilical venous blood remained constant.Mean arterio-venous differences for glutamate indicated that there was no net uptake from or release into maternal blood by the uterus. However, there was a significant (P < 0·02) uptake of glutamate by the placenta from the foetal circulation. Glutamine release from the placenta into the foetal circulation increased as the foetus matured.Significant activities of glutamate dehydrogenase, γ-glutamyl transferase, glutamine synthetase and phosphate-dependent glutaminase were found in the placenta but there was no significant relationship between the activities of these enzymes and the gestational age of the foetus. The enzyme profile indicated that the placenta has a substantial potential for net glutamine synthesis.It is concluded that, for a 140-day foetus, the release of glutamine from the placenta accounts for more than half of its nitrogen requirement. Direct placental transfer of glutamine from maternal blood accounts for only one-third of the glutamine released by the placenta into the foetal circulation of a 140-day foetus. Therefore, the remainder of the glutamine is synthesized in the placenta from glutamate. Only one-third of the glutamate required for this placental glutamine synthesis is from the glutamate released by the foetus. The remainder must be derived either from 2-oxoglutarate, as the result of aminotransferase or glutamate dehydrogenase activities, or from glutathione by the action of γ-glutamyl transferase.

Distribution of Glutaminase and Glutamine Synthetase Activities in the Human Gastrointestinal Tract

1998 ◽  
Vol 94 (3) ◽  
pp. 313-319 ◽  
Author(s):  
L. A. James ◽  
P. G. Lunn ◽  
S. Middleton ◽  
M. Elia
Keyword(s):  
Gastrointestinal Tract ◽  
Glutamine Synthetase ◽  
Large Intestine ◽  
Specific Activity ◽  
Complete Information ◽  
Duodenal Mucosa ◽  
Glutamine Metabolism ◽  
Duodenal Juice ◽  
Human Gastrointestinal Tract ◽  
Wet Weight

1. The activities of the two key enzymes involved in glutamine metabolism, glutaminase and glutamine synthetase, were measured in mucosal biopsies taken from different sites throughout the human gastrointestinal tract, from oesophagus to rectum. 2. The specific activity of glutamine synthetase was highest in the stomach (4.5 nmol glutamine formed per minute per mg of protein), but both small and large intestine and the oesophagus had little synthesizing capacity (less than 0.3 nmol of glutamine formed per minute per mg of protein). 3. Glutaminase specific activity was highest in the small intestine (53 nmol glutamate formed per minute per mg of protein by duodenal mucosa), intermediate in the large intestine and lowest in the oesophagus and stomach (less than 13 nmol of glutamate formed per minute per mg of protein). 4. The glutamine concentration in the mucosa was lower in the duodenum than in the colon (0.62 and 0.95 mmol/kg wet weight respectively), but both were much lower than the measured Km values of glutaminases obtained from these sites (3.8 and 4.0 mmol/kg wet weight respectively). 5. The concentration of glutamine in saliva, stomach juice, bile and duodenal juice suggests that very little glutamine passes into the gastrointestinal tract via these secretions. 6. The study provides the most complete information on the distribution of glutamine synthetase and glutaminase along the human gastrointestinal tract, and suggests that (i) both the small and large intestines have a high potential for glutamine metabolism, but little synthesizing capacity, thus both must derive their glutamine from other sources, and (ii) neither the stomach nor the oesophagus have a high glutaminase activity, although the stomach has substantial capacity to synthesize glutamine. The distribution of the enzymes along the gastrointestinal tract may help rationalize the use of glutamine for treating diseases that affect different parts of the gastrointestinal tract.

Glutamine metabolism in rat skeletal muscle wounded with lambda-carrageenan

1987 ◽  
Vol 252 (1) ◽  
pp. E49-E56
Author(s):  
J. E. Albina ◽  
W. Henry ◽  
P. A. King ◽  
J. Shearer ◽  
B. Mastrofrancesco ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glutamine Synthetase ◽  
Inflammatory Infiltrate ◽  
Marked Decrease ◽  
Glutamine Metabolism ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Rat Skeletal Muscle ◽  
Glutamine Synthesis ◽  
Cellular Components

Wounding with lambda-carrageenan results in a marked decrease in the intracellular-free glutamine content of rat skeletal muscle. The potential mechanisms for this finding, including alterations in glutamine release, glutamine utilization, and glutamine synthesis, were investigated in rats under pentobarbital anesthesia. Wounding did not increase glutamine release from muscle during incubation or isolated hindlimb perfusion. Wounded muscle utilized more glutamine than nonwounded muscle, as measured both by the production of [14C]O2 and of -glutamate from labeled glutamine. Maximal glutamine synthetase activity was increased by wounding. The increase in glutamine synthetase activity in wounded muscle was prevented by adrenalectomy and restored by replacement doses of corticosterone in wounded adrenalectomized animals. The decrease in muscle free glutamine induced by wounding is therefore not mediated by an increase in the release of this amino acid, nor by a reduction in the tissue capacity for glutamine synthesis, but by an increase in glutamine utilization at the site of injury. This difference is apparently determined by the utilization of glutamine by the cellular components of the inflammatory infiltrate, which were shown to be capable of active glutaminolysis.

scholarly journals Metabolic engineering of Escherichia coli for efficient production of L-alanyl-L-glutamine

2020 ◽  
Author(s):  
Jiangming Zhu ◽  
Wei Yang ◽  
Bohua Wang ◽  
Qun Liu ◽  
Xiaotong Zhong ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Glutamic Acid ◽  
Water Solubility ◽  
Glutamine Metabolism ◽  
Cell Factory ◽  
Efficient Production ◽  
Microbial Cell Factory ◽  
Good Thermal Stability ◽  
Glutamine Synthesis ◽  
Engineered Strain

Abstract Background: L-alanyl-L-glutamine (AQ) is a functional dipeptide with high water solubility, good thermal stability and high bioavailability. It is widely used in clinical treatment, post-operative rehabilitation, sports health care and other fields. AQ is mainly produced via chemical synthesis which is complicated, time-consuming, labor-intensive, and have a low yield accompanied with the generation of by-products. It is therefore highly desirable to develop an efficient biotechnological process for the industrial production of AQ.Results: A metabolically engineered E. coli strain for AQ production was developed by over-expressing L-amino acid α-ligase (BacD) from Bacillus subtilis, and inactivating the peptidases PepA, PepB, PepD, and PepN, as well as the dipeptide transport system Dpp. In order to use the more readily available substrate glutamic acid, a module for glutamine synthesis from glutamic acid was constructed by introducing glutamine synthetase (GlnA). Additionally, we knocked out glsA-glsB to block the first step in glutamine metabolism, and glnE-glnB involved in the ATP-dependent addition of AMP/UMP to a subunit of glutamine synthetase, which resulted in increased glutamine supply. Then the glutamine synthesis module was combined with the AQ synthesis module to develop the engineered strain that uses glutamic acid and alanine for AQ production. The expression of BacD and GlnA was further balanced to improve AQ production. Using the final engineered strain p15/AQ10 as a whole-cell biocatalyst, 71.7 mM AQ was produced with a productivity of 3.98 mM/h and conversion rate of 71.7 %.Conclusion: A metabolically engineered strain for AQ production was successfully developed via inactivation of peptidases, screening of BacD, introduction of glutamine synthesis module, and balancing the glutamine and AQ synthesis modules to improve the yield of AQ. This work provides a microbial cell factory for efficient production of AQ with industrial potential.

scholarly journals The regulation of glutamine and ketone-body metabolism in the small intestine of the long-term (40-day) streptozotocin-diabetic rat

1987 ◽  
Vol 242 (1) ◽  
pp. 61-68 ◽  
Author(s):  
M Watford ◽  
E J Erbelding ◽  
E M Smith
Keyword(s):  
Small Intestine ◽  
Ketone Body ◽  
Ketone Bodies ◽  
Streptozotocin Diabetes ◽  
Diabetic Rats ◽  
Glutamine Metabolism ◽  
Diabetic Rat ◽  
Coa Transferase ◽  
Glutaminase Activity

The small intestine is the major site of glutamine utilization in the mammalian body. During prolonged (40-day) streptozotocin-diabetes in the rat there is a marked increase in both the size and the phosphate-activated glutaminase activity of the small intestine. Despite this increased capacity, intestinal glutamine utilization ceases in diabetic rats. Mean arterial glutamine concentration fell by more than 50% in diabetic rats, suggesting that substrate availability is responsible for the decrease in intestinal glutamine use. When arterial glutamine concentrations in diabetic rats were elevated by infusion of glutamine solutions, glutamine uptake across the portal-drained viscera was observed. The effect of other respiratory fuels on intestinal glutamine metabolism was examined. Infusions of ketone bodies did not affect glutamine use by the portal-drained viscera of non-diabetic rats. Prolonged diabetes had no effect on the activity of 3-oxoacid CoA-transferase in the small intestine or on the rate of ketone-body utilization in isolated enterocytes. Glutamine (2 mM) utilization was decreased in enterocytes isolated from diabetic rats as compared with those from control animals. However, glutaminase activity in homogenates of enterocytes was unchanged by diabetes. In enterocytes isolated from diabetic rats the addition of ketone bodies or octanoate decreased glutamine use. It is proposed that during prolonged diabetes ketone bodies, and possibly fatty acids, replace glutamine as the major respiratory fuel of the small intestine.

scholarly journals Unusual case of amyloidosis presenting as a jejunal mass

2021 ◽  
Vol 14 (5) ◽  
pp. e240226
Author(s):  
Sachin Mohan ◽  
Elliot Graziano ◽  
James Campbell ◽  
Irshad H Jafri
Keyword(s):  
Small Intestine ◽  
Light Chain ◽  
Protein Misfolding ◽  
Unusual Case ◽  
Gi Tract ◽  
Organ Systems ◽  
Light Chain Disease ◽  
Wide Range ◽  
Amyloid Light Chain ◽  
Possible Cause

Amyloidosis constitutes a heterogeneous group of disorders of protein misfolding that can involve different organ systems. The disease can occur either in a systemic or localised manner that is well known to involve the gastrointestinal (GI) tract. GI amyloidosis can present with a wide range of symptoms including diarrhoea, bleeding and obstruction. This case illustrates a patient with localised jejunal amyloid light chain disease that was diagnosed serendipitously during a workup for haematuria. Our patient was otherwise asymptomatic, but this case underscores the importance of considering amyloidosis as a possible cause of isolated masses of the small intestine.

Regulation of Glutaminase Activity and Glutamine Metabolism

1995 ◽  
Vol 15 (1) ◽  
pp. 133-159 ◽  
Author(s):  
Norman P. Curthoys ◽  
Malcolm Watford
Keyword(s):  
Glutamine Metabolism ◽  
Glutaminase Activity

Carbohydrase activity in the pancreatic tissue and small intestine mucosa of sheep fed dried-grass or ground maize-based diets

1985 ◽  
Vol 104 (2) ◽  
pp. 435-443 ◽  
Author(s):  
A. N. Janes ◽  
T. E. C. Weekes ◽  
D. G. Armstrong
Keyword(s):  
Small Intestine ◽  
Amylase Activity ◽  
Total Activity ◽  
Pancreatic Tissue ◽  
Proximal Region ◽  
Small Intestinal Mucosa ◽  
Intestine Mucosa ◽  
Ruminant Animals ◽  
Specific Activities ◽  
Small Intestinal

SummaryTwo groups of six sheep were fed either dried-grass or ground maize-based diets for at least 4 weeks before slaughter. Samples of the small intestinal mucosa and spancreatic tissue were assayed for a-amylase, glucoamylase, maltase and oligo-l,6-glucosidase.The pancreatic tissue contained high activities of α-amylase and much lower activities of glucoamylase, maltase and oligo-1,6-glucosidase. There was no effect of diet on the specific activities of any of these enzymes in the pancreatic tissue.The activity of α-amylase adsorbed on to the mucosa of the small intestine was greatest in the proximal region of the small intestine, the activity generally declining with increasing distance away from the pylorus. There was no diet effect on the absorbed α-amylase activity.Similar patterns of distribution along the small intestine were observed for maltase, glucoamylase and oligo-1,6-glucosidase with the highest activities in t he jejunum. There was no overall effect of diet on glucoamylase or maltase specific activities and glucoamylase total activity, although the total activities of maltase and oligo-1,6-glucosidase were significantly greater for the sheep fed the ground maize-based diet (P < 0·05).It is suggested that ruminant animals may be capable of digesting large amounts of starch in the small intestine through an adaptation in the activity of the host carbohydrases.

Conversion of xanthine dehydrogenase to oxidase in ischemic rat intestine: a reevaluation

1988 ◽  
Vol 254 (5) ◽  
pp. G768-G774 ◽  
Author(s):  
D. A. Parks ◽  
T. K. Williams ◽  
J. S. Beckman
Keyword(s):  
Small Intestine ◽  
Oxygen Radicals ◽  
Total Activity ◽  
Xanthine Dehydrogenase ◽  
Oxygen Radical ◽  
Morphological Evidence ◽  
Cellular Injury ◽  
Rat Intestine ◽  
Entire Small Intestine ◽  
Ischemic Intestine

Oxygen radicals derived from xanthine oxidase (XO) are important mediators of the cellular injury associated with reperfusion of ischemic intestine, stomach, liver, kidney, and pancreas. XO exists in nonischemic tissue predominantly as xanthine dehydrogenase (XDH) and converts to oxygen radical-producing XO with ischemia. Grinding intestine under liquid nitrogen and placing the powder in phosphate buffer (pH 7.0) containing thiol reductants and protease inhibitors adequately preserved total XDH + XO activity and the percentage in the oxidase form (%XO) for 24 h. Total activity in nonischemic intestine ranged from 374 nmol.min-1.g-1 in duodenum to 138 nmol.min-1.g-1 in ileum, while XO activity was approximately 19% of total activity throughout the entire small intestine. The rate of XDH conversion to XO during normothermic ischemia varied only slightly throughout the intestine, increasing 13% per hour to 34, 46, and 61% XO after 1, 2, and 3 h of ischemia, respectively. Our results contrast with previous reports where XDH conversion to XO occurred within 60 s ischemia but are consistent with physiological and morphological evidence of ischemic injury and provide further support for involvement of XO in intestinal injury associated with ischemia.

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