Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have examined the pattern of synthesis of the glycoprotein form of invertase and of the smaller carbohydratefree from in synchronous culture to obtain further infromation concerning their biosynthetic relationship. Saccharomyces mutant 1710 was chosen since its invertase production is almost completely derepressed during growth in 0.1 M mannose medium. The large enzyme, unlike the small form, binds to concanavalin A-Sepharose, and on this basis the two types can conveniently be separated for analysis. Large invertase was produced throughout the cell cycle. Synthesis of the small invertase was periodic; the single burst occurred at or close to the budding stage. Tunicamycin, which inhibits the sypthesis of external glycoproteins, halted formation of the large enzyme but not of the small form, and there was no accumulation of invertase activity with the properties of the small enzyme. Hence, it is unlikely that the small form is a precursor of the large one. Despite marked differences in their amino acid compositions, the two enzymes have many similarities. They are probably, in part, the products of the same gene(s), and the differences between them may largely reflect differences in post-translational processing.
 ...
PMID:Large and small invertases and the yeast cell cycle. Pattern of synthesis and sensitivity to tunicamycin. 32 Oct 22

Invertase formation in the yeast Saccharomyces cerevisiae is subject to repression by hexoses in the growth medium. Mutagen-induced (ethyl methanesulfonate or N-methyl-N-nitro-nitrosoguanidine) invertase hyperproducer mutants have been derived from the SUC3 MAL3 strain EK-6B by selecting for their ability to grow on media containing the sugar raffinose plus 2-deoxy-D-glucose (2DG). Raffinose like sucrose is a betta-fructoside which can be hydrolyzed by yeast invertase (beta-fructoside which can be hydrolyzed by yeast invertase (beta-fructofuranoside fructohydrolase). These mutants, designated dgr, produce higher levels of invertase (pi-glucosidase levels are also elevated but to a lesser extent) under conditions normally repressing invertase biosynthesis in the parent. Invertases of mutants dgr2 and dgr3 are indistinguishable from that of EK-6B with respect to their Km's for sucrose and thermal labilities. Genetic studies revealed that dgr2 and dgr3 are recessive and unlinked to the SUC3 gene.
 ...
PMID:Genetic control of invertase formation in Saccharomyces cerevisiae. II. Isolation and characterization of mutants conferring invertase hyperproduction in strain EK-6B carrying the SUC3 gene. 36 57

Concanavalin A (Con A) was utilized free, bound to Sepharose 4 B or cross-linked to glutaraldehyde to investigate the possibility of binding this lectin to radish beta-fructosidase (E.C.3.2.1.26). The choice of cross-linked Con A as affinoadsorbent is discussed and standard conditions for binding are defined. Specificity of precipitation of this enzyme by the lectin was especially investigated. Thus, the possibility of binding was tested in the presence of high ionic strength, ethylene glycol, alpha-methyl mannoside, alpha-methyl glucoside and during periodate oxidation of the enzyme. Based on the interactions observed between beta-fructosidase and Con A under these conditions it is concluded that the saccharide binding site of the lectin is primarily involved with a secondary contribution from the hydrophobic site. The specificity of binding and the complete precipitation of beta-fructosidase activity by the insolubilized lectin imply that all beta-fructosidase activity measured in Raphanus sativus seedling extracts is linked to (a) glycoprotein form(s) of this enzyme.
 ...
PMID:Evidence for the glycoprotein nature of radish beta-fructosidase. 43 59

Teratocarcinoma stem cells maintained in the undifferentiated state express a carbohydrate-binding component that recognizes oligomannosyl residues. This cell surface molecule is detected by a rosetta assay in which the stem cells form rosettes with glutaraldehyde-fixed trypsinized rabbit erythrocytes. Addition of simple sugars to the assay mixture has little effect, but rosette formation is inhibited by a series of mannose-rich glycoproteins (yeast invertase, yeast mannans and horseradish peroxidase). Periodate oxidation eliminates the inhibitory activity of invertase whereas pronase digestion has little effect, indicating that carbohydrate moieties are essential for inhibition. Invertase and its glycopeptide derivatives also inhibit the reaggregation of dispersed stem cells and promote the dissociation of preformed aggregates. These results suggest that intercellular adhesion of teratocarcinoma stem cels may be the consequence of the interaction of a lectin-like component detected in the rosette assay with a complementary oligosaccharide receptor on adjacent cells.
 ...
PMID:Teratocarcinoma stem cells have a cell surface carbohydrate-binding component implicated in cell-cell adhesion. 47 26

Brush border sucrase and alkaline phosphatase activities are considerably enhanced in the intestine of ascorbic acid deficient guinea-pigs. Similar increase in the uptake of D-glucose and L-alanine also occurs in chronic vitamin C deficiency. However the permeability of D-glucose and L-alanine in the intestine of animals fed with large doses of vitamin C is severely depressed, with a reduction in the levels of sucrase and alkaline phosphatase activities.
 ...
PMID:Effect of chronic hypo and hypervitaminosis C on the brush border enzymes and the intestinal uptake of glucose and alanine. 47 73

A modified Roux-en-y repositioning of rat proximal small intestine resulted in a gut segment (A) exposed only to digestive secretions, but not to food and a gut segment (B) exposed to food, stomach juice and by reflux only to digestive secretions, and a third segment (C) exposed to both, food and digestive secretions. The changes in segment A were qualitatively very similar to those occurring after removal of luminal nutrition (intravenous feeding, self-emptying blind loop, and Thiry Vella loop). These findings support the hypothesis that the presence of luminal nutrition is a major factor regulating mucosal mass and enzyme activity in rat proximal small intestine. The changes in the luminal environment in segment B caused an increase in mucosal mass (in the proximal half only), an increase in sucrase activity which paralleled the increase in mucosal mass, and no change in activity of alkaline phosphatase which in fact was a decrease in activity ;at the cellular level'. Later on the net absorption of sodium and potassium was improved and the disappearance of galactose was unchanged when referred to unit length of small intestine.In segment C there was a small increase in mucosal mass, an increase in activity only for alkaline phosphatase, and an improvement of the net absorption of sodium without changes in the disappearance of galactose. These changes were compatible with a more proximal promotion of a distal gut segment.
 ...
PMID:Analysis of the effects of food and of digestive secretions on the small intestine of the rat: III. Mucosal mass, activity of brush border enzymes, and in vivo absorption of galactose, sodium, and potassium. 68 Jun 2

The functional and structural characteristics of the ileal remnant of rat intestine were examined four weeks after 45%, 70% or 95% proximal resection. The increase in villus height in the ileal remnant had alfread reached its maximum after a resection of 45%, whereas a further increment in the length of the crypts occurred after 70% resection. There was an increase in the number of enterocytes per unit length of villus and a rise in the DNA content per unit weight of mucosal scrapings, which testifies to the development of mucosal hyperplasia in this situation. The specific activities of sucrase, measured biochemically, and of nonspecific esterase, determined histochemically, were reduced in proportion to the extent of the resection. Similarly, the uptakes of L-phenylalanine and of beta-methyl-D-glucoside by intestinal rings in vitro were progressively diminished in the ileal remnant. There was an increase in the rate of disappearance of glucose from a perfused loop in vivo, when expressed in terms of unit intestinal length. Galactose absorption remained unchanged, but when expressed in terms of unit dry tissue, was significantly reduced, in agreement with the diminished transport of both amino-acids and monosaccharides in vitro.
 ...
PMID:The relationship between the functional and structural alterations in the rat small intestine following proximal resection of varying extents. 68 86

Carboxypeptidase Y from Saccharomyces cerevisiae contains 14% mannose, the only neutral sugar present. An antiserum can be raised in rabbits which reacts with both the protein and the sugar moieties of the enzyme. This antiserum also precipitates yeast invertase and yeast cell wall mannan. Thus carboxypeptidase Y, which is known to be localized in yeast vacuoles, is very probably a mannoprotein. Tunicamycin inhibits the apparent formation of carboxypeptidase Y to a similar extent as that of the externally localized mannoprotein, invertase. No accumulation of an inactive nonglycosylated or partly glycosylated carboxypeptidase Y occurs as determined by the immunoprecipitation technique. Tunicamycin also inhibits the apparent formation of proteinase A, whereas it does not affect the increase in the activities of a number of other enzymes. It is suggested that in the synthesis of glycoproteins there exists a regulatory link between the synthesis of their polypeptide chains and the reactions involved in their glycosylation.
 ...
PMID:Inhibition of the apparent rate of synthesis on the vacuolar glycoprotein carboxypeptidase Y and its protein antigen by turicamycin in Saccharomyces cerevisiae. 79 Oct 99

1. The alpha-galactosidase of Saccharomyces carlsbergensis in an inducible enzyme which is localized mainly outside the cell membrane and which is secreted into the culture medium in increasing amounts during the growth cycle. 2. The soluble form of alpha-galactosidase localized inside the cell appears to have the same characteristics as the external one, contrasting with the different forms found in the case of invertase. Although some activity is membrane-bound, this activity, when solubilized with detergent, has the same characteristics as the external form of the enzyme. 3. A procedure has been developed by which the enzyme has been purified using batch adsorption with DEAE-Sephadex and column chromatography in DEAE-Sephadex, DEAE-cellulose and Sephadex G-200, using the supernatant of a culture of Saccharomyces carlsbergensis grown in yeast/nitrogen base complemented with galactose. 4. The purified enzyme, which is homogeneous by chromatographic criteria and polyacrylamide gel electrophoresis, appears to be glycoprotein. 5. Invertase copurifies with the alpha-galactosidase but because of its lower stability, together with the fact that the synthesis of both enzymes can be controlled separately, it was possible to obtain preparations in which the contaminant activity was approximately 1%.
 ...
PMID:alpha-Galactosidase from Saccharomyces carlsbergensis. Cellular localization, and purification of the external enzyme. 89 41

At an average of 32 days after a modified Roux-en-y repositioning of rat small intestine, the mucosal mass, mucosal composition, in vivo absorption of galactose and the activity of maltase, sucrase and alkaline phosphatase were measured. In the gut segment with digestive secretions but without food (A) the only change was a decrease of sucrase activity which occurred most probably at the cellular level. In the gut segment with food and gastric juice and a reflux of digestive secretions (B) complex changes took place. An increase in mucosal mass was not accompanied by an increase in galactose absorption. There was a high increase of sucrase activity, a moderate increase of maltase activity and a tendency of the alkaline phosphatase activity to decrease. The changes (increase in mucosal mass and total enzyme activity, but no changes in activity at the cellular level) in the segment exposed to both digestive secretions and food (C) were compatible with a more proximal promotion of a distal gut segment.
 ...
PMID:An experimental model for studies on the effects of food and digestive secretions on the digestive-absorptive capacity of rat small intestine. 89 9


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>