Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.32 (bromelain)
 1,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human kidney gamma-glutamyl transpeptidase has been purified by a procedure involving Lubrol extraction, acetone precipitation, treatment with bromelain, and column chromatography on DEAE-cellulose and Sephadex G-150. The final preparation is a glycoprotein (molecular weight of approximately 84,000) composed of two nonidentical glycopeptides (molecular weights of 62,000 and 22,000). The isozymic forms, separable by isoelectric focusing, have different contents of sialic acid. The utilization of L-glutamine (which is both a gamma-glutamyl donor and acceptor) is stimulated about 3-fold by maleate in contrast to 10-fold stimulation of glutamine utilization by the rat kidney enzyme. The gamma-glutamyl analogs, 6-diazo-5-oxo-L-norleucine (DON) and L-azaserine inactivate the human kidney enzyme with respect to its transpeptidase and hydrolase activities. Inactivation is prevented by gamma-glutamyl substrates (but not by acceptor substrates) and is accelerated by maleate. [14C]DON reacts covalently and stoichiometrically at the gamma-glutamyl site, which was localized to the light subunit of the enzyme. The light subunit of human transpeptidase closely resembles that of rat kidney enzyme in having the gamma-glutamyl binding site, and similar molecular weight and amino acid composition. The heavy subunits of the two enzymes are markedly different in both molecular weight and amino acid content; this may account for differences observed in acceptor amino acid specificity and in the magnitude of the maleate effect.
 ...
PMID:Human kidney gamma-glutamyl transpeptidase. Catalytic properties, subunit structure, and localization of the gamma-glutamyl binding site on the light subunit. 1 63

Gamma-Glutamyl transpeptidase was purified from rat kidney by a procedure involving Lubrol extraction, acetone precipitation, ammonium sulfate fractionation, treatment with bromelain, and column chromatography on DEAE-cellulose and Sephadex G-100. The final preparation (enzyme III), which exhibits a specific activity about 8-fold higher than that of the purified rat kidney transpeptidase previously obtained in this laboratory (enzyme I), was apparently homogeneous on polyacrylamide gel electrophoresis. Enzyme III is a glycoprotein containing 10% hexose, 7% aminohexose, and 1.5% sialic acid; a tentative molecular weight value of about 70,000 was obtained by gel filtration. Enzyme III has a much lower molecular weight and a different amino acid and carbohydrate content than the less active rat kidney transpeptidase preparation previously obtained, but obtained, but the catalytic properties of these preparations are virtually identical. It is suggested that bromelain treatment may liberate the transpeptidase from a brush border complex that contains other proteins. An improved method is described for the isolation of the higher molecular weight form of the enzyme (enzyme I) in which affinity chromatography on concanavalin A-Sephrose is employed. The purified transpeptidase (enzyme III) is similar to the phosphate-independent maleate-stimulated glutaminase preparation obtained from rat kidney by Katunuma and colleagues with respect to amino acid and carbohydrate content, apparent molecular weight, and relative transpeptidase and maleate-stimulated "glutaminase" activities. Both of these enzyme preparations are much more active in transpeptidation reactions with glutathione and related gamma-glutamyl compounds than with glutamine. In the absence of maleate, the enzyme catalyzes the utilization of glutamine (by conversion to gamma-glutamylglutamine, glutamate, and ammonia) at about 2% of the rate observed for catalysis of transpeptidation between glutathione and glycylglycine; the utilization of glutamine occurs about 8 times more rapidly in the presence of 0.1 M maleate. The transpeptidation and maleate-stimulated glutaminase reactions catalyzed by both enzyme preprations are inhibited by 5 mM L-serine in the presence of 5 mM sodium borate. Studies on gamma-glutamyl transpeptidase and maleate-stimulated glutaminase in the kidneys of fetal rats, newborn rats, and rats after weaning showed parallel development of these activities. The evidence reported here and earlier work in this laboratory strongly support the conclusion that maleate-stimulated glutaminase activity is a catalytic function of gamma-glutamyl transpeptidase. The studies on the ontogeny of gamma-glutamyl transpeptidase and other data are considered in relation to the proposal that this enzyme is involved in amino acid and peptide transport. Its possible role in renal formation of ammonia is also discussed.
 ...
PMID:Identity of maleate-stimulated glutaminase with gamma-glutamyl transpeptidase in rat kidney. 23 5

Four pancreatocholangiocarcinoma cell lines (HPC-Y1, HPC-YT, MIA PaCa-2, and HChol-Y1) were established to propagate in a protein-free, chemically defined medium. High gamma-glutamyl transpeptidase (GGTP) activities were showed in their spent media (designated as the secreted (GGTP). Their GGTP activities in the spent media were 125, 85, 110, and 153 IU/L/mg of lyophilized spent media, whereas GGTP activities extracted from their cancer cell lines with bromelain were 105, 37, 86, and 112 IU/L/1 x 10(6) cells, respectively. The chemical characteristics of the GGTPs in the spent media from these cell lines resembled one of the GGTPs, sialic acid-rich GGTP, extracted from normal human pancreas with bromelain treatment as follows: the GGTPs secreted from the cancer cell lines bound to an anion exchange column moved fast on electrophoresis and then showed decreased electrophoretic mobility with neuraminidase treatment, showed a high affinity for concanavalin A and lentil lectin columns, and had an acidic isoelectric point. However, the elution patterns of erythroagglutinating phytohemagglutinin (E-PHA) column chromatography and thermostability tests demonstrated clear differences between the carcinoma GGTPs both in the spent media and cell lines and the sialic acid-rich GGTP of normal pancreas, namely the carcinoma GGTPs treated with neuraminidase showed affinity to E-PHA columns, and, in addition, the GGTPs in the spent media showed an apparent heat resistance at 56 degrees C. These findings indicate that the carcinoma GGTPs have a different oligosaccharide structure from that in normal pancreatic GGTPs.
 ...
PMID:Characterization of variant gamma-glutamyl transpeptidase produced by pancreatocholangiocarcinoma cell lines in a protein-free, chemically defined medium. 256 34

Two different types of gamma-glutamyl transpeptidase (gamma-GTP) were extracted from human pancreas by protease treatments such as bromelain. Furthermore, human pancreatic gamma-GTP, extracted with trypsin, was separated into two different components by additional treatment with bromelain. One component displayed fast electrophoretic mobility during polyacrylamide gel electrophoresis and an apparent affinity for an anion-exchange column, while the other showed slow electrophoretic mobility and passed through the anion-exchange column with starting buffer. In addition, the percentage affinity to concanavalin A (Con A) of the former was 52.2% and of the latter only 7.2%. On heat stability, the former was more sensitive than the latter at 56 degrees C. These results indicate the existence of two types of gamma-GTP in human pancreas.
 ...
PMID:Two types of human pancreatic gamma-glutamyl transpeptidase. 285 33

A cDNA hybridizable to that of rat gamma-glutamyl transpeptidase (GGT) was cloned from a cDNA library of human fetal liver. The insert of the cDNA clone contained 1866 bp consisting of an open reading frame (ORF) of 1709 bp (569 amino acids (aa), N-terminal portion truncated) and a 135-bp 3'-untranslated region followed by a polyadenylated tail. In parallel, amino acid sequences of N-terminal portions of heavy and light chains of a purified human GGT were determined. Two stretches of amino acid sequences identical to the N-terminal sequences of heavy and light chains were found in the ORF. We therefore concluded that the clone is a cDNA for human GGT. From the amino acid sequence deduced from cDNA, the heavy and the light chains of the purified enzyme are estimated to be composed of 351 aa (Mr 38,336) and of 189 aa (Mr 20,000), respectively. The heavy chain is preceded by a signal peptide of at least 29 aa presumed to be cleaved by bromelain treatment. Six putative N-glycosylation sites are present in the heavy subunit region and one in the light subunit region. Primary structure and hydrophobicity profile are closely similar to those of rat GGT.
 ...
PMID:The primary structure of human gamma-glutamyl transpeptidase. 290 98

Recent evidence suggests that gamma-glutamyl transpeptidase may be involved in the transport of amino acids into the lactating mammary gland. The enzyme also is secreted in milk and is associated mainly with milk membranes. The objective of this study was to purify and characterize gamma-glutamyl transpeptidase from milk membranes. The enzyme has been purified from milk membranes by solubilization with Lubrol WX; treatment with acetone, deoxylcholate, and bromelain; and chromatography on ion exchange and molecular-sieving resins. gamma-Glutamyl transpeptidase was purified over 11,000-fold from milk. Electrophoresis on sodium dodecyl sulfate polyacrylamide gels indicates that the enzyme is composed of two subunits with molecular weights of 57,000 and 25,500. Both subunits are glycoproteins and have been identified in the sodium dodecyl sulfate polyacrylamide gel electrophoresis patterns of whole milk membrane. Kinetic characteristics of the purified enzyme are similar to those determined for intact milk membranes and lactating mammary tissue indicating that the purified enzyme has not been modified functionally by the purification procedure.
 ...
PMID:Purification and identification of gamma-glutamyl transpeptidase of milk membranes. 610 10