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)

gamma-Glutamyl transpeptidase is associated with the membranes of a number of epithelial and lymphoid cells. When the enzyme is isolated from rat kidney by a method involving detergent extraction and affinity chromatography, an aggregate of molecular weight greater than 200,000 (heavy form) is obtained. Treatment of the heavy form with bromelain yields a light form of the enzyme (molecular weight of approximately 68,000), which is separable by isoelectric focusing into 12 enzymatically active isozymes which are very similar with respect to catalytic behavior, content of amino acids, hexoses, and aminohexoses, but which differ significantly in sialic acid content. Treatment with neuraminidase converts the acidic isozymes to more basic forms. Each isozyme dissociates in sodium dodecyl sulfate into two nonidentical glycopeptides (molecular weights of 46,000 and 22,000) which can be cross-linked with dimethylsuberimidate to yield a species with an apparent molecular weight of 70,000, which indicates that the isozymes are dimers. Physical and immunological studies indicate that the heavy form of the enzyme contains the dimeric light form as well as other membrane proteins.
 ...
PMID:Subunit structure and isozymic forms of gamma-glutamyl transpeptidase. 0 76

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

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

Gamma-glutamyl transpeptidase (gamma-GTP) was partially purified from human normal pancreas, pancreatic carcinoma and a human pancreatic cancer cell line, HPC-Y1. The characteristics of gamma-GTP from all three samples appeared to be identical. The estimated molecular weight of samples solubilized with Triton X-100 was 210K and that of bromelain-solubilized gamma-GTP was 110K. On polyacrylamide gel electrophoresis, the main band in both the Triton- and the bromelain-solubilized gamma-GTP of these samples had similar electrophoretic mobility. The percentages binding with concanavalin A were 52%-62%, while on isoelectric focusing the pI values were 3.40-3.45. It was concluded that the heterogeneity of the gamma-GTP isoenzyme could not be identified by either gel filtration or polyacrylamide gel electrophoresis, and it is necessary to investigate the modification of carbohydrate structure on tumor.
 ...
PMID:Characterization of gamma-GTP in a human pancreatic cancer cell line. 614 49

gamma-Glutamyl transpeptidase (GGT) was extracted from squamous cell carcinoma tissues of human skin (SCC) by Triton X-100 and bromelain treatment, and some of its biochemical properties were compared with those of GGT extracted from eccrine gland-rich tissue and normal kidney. GGT activity significantly increased in SCC, but there was no definitive differences in enzymological properties between GGT of SCC and normal tissue enzyme. However, GGT of SCC was distinguishable from those of normal tissues by isoelectric point, electrophoretic mobility, and sensitivity to neuraminidase treatment. These results indicate that GGT of SCC has some variant properties which may be related to skin carcinogenesis.
 ...
PMID:Properties of gamma-glutamyl transpeptidase in squamous cell carcinoma. 809 48