Gamma Glutamyl Transpeptidase: Measurement and Development in Guinea Pig Small Intestine

Cohen, Michael I.; Gartner, Lawrence M.; Blumenfeld, Olga O.; Arias, Irwin M.

doi:10.1203/00006450-196901000-00001

Cited by 33 publications

(18 citation statements)

References 21 publications

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“…It has been suggested that GGTP activity may play a role in the intestinal hydrolysis of peptides and proteins containing y-glutamyl bonds, such as glutathion, folic acid, collagen, or gluten [8], but the presence of this bond in proteins has been questioned recently [5].…”

Section: Discussionmentioning

confidence: 99%

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Enzymatic Activity Hydrolyzing γ-Glutamyl-β-Naphthylamide in Human Intestine during Adult and Fetal Life

et al. 1973

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ExtractThe enzymatic activity hydrolyzing 7-glutamyl-/3-naphthylamide (7-glutamyltranspeptidase, GGTP) was studied in the small intestine of human adults and fetuses. Surgical biopsies taken from the proximal jejunum approximately 10 cm from the ligament of Treitz served as the source of the enzyme for adult subjects. The entire small bowel was obtained from fetuses of different ages and divided into three thirds for enzymatic assay. All samples were frozen immediately and used within 1-4 months. It was shown that enzymatic activities stored at -20° are stable for that period.The GGTP activity was enhanced by the presence of glycylglycine in the incubation mixture, the maximal activation being 5.2-fold ± 0.65-fold (mean db 1 SD) when the dipeptide concentration was 40 HIM. The pH optimum for GGTP activity was 9.0 both in the presence and in the absence of glycylglycine. Glycylglycine activation and pH activity curves were similar for the proximal jejunum of adults and of two fetuses (17 and 20 weeks old).The specific activity of GGTP significantly increased from the proximal to the distal third at every fetal age (P = 0.01-0.001). The specific GGTP activity (U/g protein) of the proximal jejunum of the adult was 2.2 ± 0.5 (mean ± 1 SD). It was thus approximately one-eighth that found in the proximal third of the fetal small bowel (18.4 ± 7.7 U/g protein).In order to investigate the subcellular localization of GGTP activity, isolated brush borders and brush border membranes were prepared from surgical biopsies of adult proximal jejunum. The GGTP-and sucrase (EC. 3.2.1.26)-specific activities increased in a parallel way from the brush border to the membrane fraction. This result indicates that at least part of the GGTP activity is located in this membrane.

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Section: Discussionmentioning

confidence: 99%

“…several animal tissues [8], as well as in human intestine Peptidase activity able to split y-glutamyl peptides (y- [12]. In this paper the enzymatic activity hydrolyzing yglutamyl-/?-naphthylamide was studied in human intestine during adult and fetal life.…”

Section: Introductionmentioning

confidence: 99%

Enzymatic Activity Hydrolyzing γ-Glutamyl-β-Naphthylamide in Human Intestine during Adult and Fetal Life

et al. 1973

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“…The oligoaminopeptidase and the y-glutamyltranspeptidase are the only brush border peptidases whose developmental pattern has been studied in human (4,18), rat (26), and guinea pig (8) intestine.…”

Section: Speculationmentioning

confidence: 99%

“…Dipeptides and tripeptides, as well as larger peptides, may also be hydrolyzed in the brush border membrane, where the following peptidases are present: (1) the oligoaminopeptidase (15,16,20,36), which is able to hydrolyze di-and oligopeptides up to at least octapeptides (20); (2) a dipeptidylamino-peptidase IV (1, 3,5,38), which is able to release N-terminal dipeptides from peptides that have penultimate proline, alanine, or leucine residues (40); (3) the aminopeptidase A (1, 2, 3, 5), probably involved in the digestion of oligopeptides containing glutamic (and aspartic) acid (19); (4) a carboxypeptidase (1, 3, 5), which is probably able to hydrolyze the C-terminal residue from a large series of oligopeptides that have proline as the C-penultimate aminoacid (1 1); (5) the yglutamyltranspeptidase (2,4,6,8), presumed to be involved in the transport of amino acids and dipeptides across the brush border (14,39). Suitable substrates for the assay of these five brush border peptidases are: L-leucyl-, glycyl-L-prolyl-, a-L-glutamyl-P-naphthylamide, N-CBZ-L-prolyl-L-leucine, and y-L-glutamyl-P-naphthylamide, respectively.…”

Section: Speculationmentioning

confidence: 99%

Development of Brush Border Peptidases in Human and Rat Small Intestine during Fetal and Neonatal Life

1981

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Pediatr. Res. 15: 991-995 (1981) SummaryThe cytosol peptidase activities hydrolyzing glycyl-L-leucine and L-leucyl-glycyl-glycine as well as the activities of the brush border peptidases (oligoaminopeptidase, aminopeptidase A, y-glutamyltranspeptidase, dipeptidyl-aminopeptidase IV, and carboxypeptidase) are present in rat fetuses during the early differentiation of the intestine (17th to 19th days of fetal life); they increase then at a different rate, reaching a maximum at various times, in the second and third wk after birth, and then decrease to the adult values during the first month of postnatal life. Only the oligoaminopeptidase activity increases steadily after birth, reaching maximal activity in the last decade of the first month.In human fetuses aged between 8 and 22 wk, the y-glutamyltranspeptidase was the only brush border peptidase found to be higher than in adults and children. On the other hand, the arninopeptidase A is remarkably reduced. The dipeptidylaminopeptidase IV and the carboxypeptidase are already at adult level in the youngest fetuses, and the oligoaminopeptidase increases during the period of fetal life studied; at the end of this period, the enzyme activity does not differ from the values found in children and adults.

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“…This transport mechanism may function in the kidney tubules, at the brain-cerebral spinal fluid barrier (23), intestine (2,4), and possibly also in hepatocytes of fetal animals, of rat hepatomas (12), and man. It could be speculated that the rapid growth of fetal liver as well as the underlying processes leading to the changes observed in hepatomas and after P C S create the need for a augmented amino acid transport.…”

Section: Groupmentioning

confidence: 99%

γ-Glutamyltranspeptidase in the Rat Liver after Portacaval Shunt

et al. 1976

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Extractweight have been re~orted (I. 15). The metabolism of bile salts and y-Glutamyltranspeptidase (GGTP) activity was studied in livers of rats submitted to an end-to-side portacaval shunt (PCS) and in developing animals. To correlate the evolution of the enzymatic activity measured in vitro, histochemical techniques were used to localize enzyme activity in liver tissue. The GGTP activity in the adult rats was low and amounted to 2.0 =k 0.1 pmol/min/g. During fetal development the enzyme activity rose beginning on the 15th gestational day from 630 A 97 to 1,058 + 20 on the first postnatal day. I'hen the values declined and reached nearly adult values from the 10th postnatal day.After PCS the GGTP activity exhibited a three-to sixfold increase (130 + 69 to 371 + 131) as compared with uneperated adult controls (53 & 13). The highest levels corresponded to those observed between the 3rd and 5th postnatal day in the developing rats. The histochemistry of GGTP in the fetal and newborn liver showed a regular distribution of the enzyme as a fine deposit in the hepatocytes throughout the whole tissue. Ten days after birth the activity was low, at the same level as in the adult rat. In the period after P C S hepatocytes began to show signs of enzymatic activity at the periphery of the hepatic lobules, which subsequently spread through the whole lobules. The increase of GGTP activity after P C S equaled the activity found in fetal animals. That correlated well in both groups with the reappearance of histologically demonstrable enzyme activity in hepatocytes. SpeculationThe consequences of portacaval shunt might be associated with the derepression of an enzyme normally present only in fetal and neonatal rat liver. Since GGTP plays a role in the y-glutamyl cycle, and is responsible, supposedly, for the transport of amino acids into the cell, it may be that in fetal liver and after P C S augmented cellular amino acid transport is an expression of growth and transformation processes.The end-to-side PCS in the rat represents an appropriate model to study experimental hyperammonemia (7, 15) because of the shunting of portal blood to the systemic circulation. In addition to hyperammonemia, portacaval shunting leads to marked changes of the quantity and composition of the blood reaching the liver. The consequences of the shunt operation are therefore multiple. Encephalopathy, testicular atrophy, and changes in body and liver of certain amino ac'ids seeks to'be affected as well (14,(24)(25)(26).These significant morphologic and functional changes are likely to be interpreted as a consequence of shunt-induced alterations in the metabolic stimulation of the liver. Despite considerable work in this field, no common denominator has been found to define the underlying hepatic process of the transformations induced by PCS. To our knowledge the specific hypothesis has not been tested of whether some of the consequences of PCS on hepatic metabolism might be considered as a regression of the liver cell function to a more immature or embr...

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Gamma Glutamyl Transpeptidase: Measurement and Development in Guinea Pig Small Intestine

Cited by 33 publications

References 21 publications

Enzymatic Activity Hydrolyzing γ-Glutamyl-β-Naphthylamide in Human Intestine during Adult and Fetal Life

Enzymatic Activity Hydrolyzing γ-Glutamyl-β-Naphthylamide in Human Intestine during Adult and Fetal Life

Development of Brush Border Peptidases in Human and Rat Small Intestine during Fetal and Neonatal Life

γ-Glutamyltranspeptidase in the Rat Liver after Portacaval Shunt

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