Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Soybean soluble polysaccharides (SSPS) extracted from soybean cotyledons are acidic polysaccharides and have a pectin-like structure. The results of a structural analysis of SSPS by using polygalacturonase (PGase) and rhamnogalacturonase (RGase) clarified that the main backbone consisted of galacturonan (GN) and rhamnogalacturonan (RG), which were composed of the diglycosyl repeating unit, -4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-. The side chains of beta-1,4-galactans, branched with fucose and arabinose residues, were linked to the C-4 side of rhamnose residues in the RG regions. The degree of polymerization (dps) of GN, which linked the RG regions together, was estimated to be about 4-10 residues, and some were modified with xylose residues on the C-3 side of the galacturonates. The dps of GN at the reducing end of SSPS was estimated to be about 7-9 residues. Moreover, the fragment of the basic structure of the RG region, -[4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-]2-, some of which had long-chain beta-1,4-galactans branched on the C-4 side of rhamnose residues, were liberated from SSPS by the RGase treatment. The dps of the galactan side chain was estimated to be about 43-47 residues by an analysis of the digestion products from the beta-galactosidase treatment.
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PMID:Structural studies by stepwise enzymatic degradation of the main backbone of soybean soluble polysaccharides consisting of galacturonan and rhamnogalacturonan. 1216 53

Larval and adult Psacothea hilaris feed on mulberry wood and leaves, respectively. High levels of endogenous activity against the major dietary carbohydrates, cellulose, hemicellulose, starch and soluble sugars were secreted in the gut of larvae and adults. Activity against pectin was also high and multiple polygalacturonase (EC 3.2.1.15) components were secreted in the gut of larvae. One glycanase component, beta-EG1, which was primarily an endo-beta-1,4-glucanase (EC 3.2.1.4) and another, beta-EG2, which was mostly an endo-beta-1,4-xylanase (EC 3.2.1.8), were also secreted, while at least four additional components hydrolysed laminarin, lichenin and crystalline cellulose. The beta-glycosidase component beta-GD1 was associated with most of the beta-mannosidase (EC 3.2.1.25) and beta-xylosidase (EC 3.2.1.37) activity secreted in the gut of larvae, while another, beta-GD2, was a beta-glucosidase (EC 3.2.1.21), the activity of which was directed against cellobiose and other beta-linked disaccharides, and a beta-fucosidase (EC 3.2.1.38). A beta-galactosidase (EC 3.2.1.23), which did not hydrolyse lactose, was also secreted, as were distinct beta-N-acetylhexosaminidase (EC 3.2.1.52), trehalase (EC 3.2.1.28), alpha-L-arabinosidase (EC 3.2.1.55), alpha-galactosidase (EC 3.2.1.22) and a minimum of four alpha-glucosidase (EC 3.2.1.20) components, one of which was also likely to be associated with a peak of alpha-mannosidase (EC 3.2.1.24) activity. The alpha-glucosidase components varied in their specificity for alpha-linked disaccharides, but none was active against sucrose, which was hydrolysed by a beta-fructofuranosidase (EC 3.2.1.26) component. Overall average levels of activity in larvae were twice those of adults, but the secretion of individual carbohydrases in both was not regulated in response to the relative abundance of particular carbohydrate components in their respective diets.
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PMID:Diet and carbohydrate digestion in the yellow-spotted longicorn beetle Psacothea hilaris. 1277 Apr 76

Watermelon fruit exhibit acute softening and placental-tissue water soaking following short exposure to exogenous ethylene. Experiments were performed to address transcript abundance and activities of cell wall and membrane hydrolases in placental tissue in response to treatment of watermelon fruit with ethylene. Watermelon fruit were harvested at immature and full-ripe stages and exposed to 50 microL L(-1) ethylene for 6 days at 20 degrees C. Ethylene affected the abundance of transcripts for PME (EC 3.2.1.11), and alpha-(EC 3.2.1.22) and beta-GAL (EC 3.2.1.23) but these effects were dependent on fruit maturity and appeared not to be associated with the water-soaking syndrome. PG (EC 3.2.1.15) and EXP mRNAs accumulated significantly in response to ethylene exposure. Additionally, the levels of mRNA and activities of LOX (EC 1.13.11.12), PLC (EC 3.1.4.3) and PLD (EC 3.1.4.4) were elevated in fruit of both maturity classes exposed to ethylene and were temporally associated with the visible symptoms of water soaking. The activity trends and transcript abundance in ethylene- compared with air-treated fruit indicate that PG, EXP, LOX, PLC and PLD levels increase with the onset and development of the water-soaking disorder and support the view that catabolic reactions targeting the membranes and cell-walls contribute to the disorder.
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PMID:Ethylene-induced gene expression, enzyme activities, and water soaking in immature and ripe watermelon (Citrullus lanatus) fruit. 1512 25

The drought-tolerant legume Hedysarum coronarium is a Mediterranean species valued as a forage crop for its high performance in stressful conditions. The plant shows peculiar capabilities of nodulating above pH 9 and thriving in highly calcareous soils. With the aim of providing an adequate characterization of its bacterial symbiotic partner, a study was undertaken, approaching from several viewpoints the physiology and structural features of bacteria isolated from nodules of H. coronarium. Tests involved trophic capabilities on different carbon and nitrogen sources, vitamin requirements, and resistance to factors including antibiotics, heavy metals, salinity, pH, and temperature. Enzyme activities, including those of cellulase, pectinase, urease, beta-galactosidase, nitrate and nitrite reductase, were evaluated. The DNA G + C percentage content was determined. Species-specific bacteriophages were isolated and a strain-typing grid established. In order to characterize further and fingerprint the different Rhizobium 'hedysari' isolates, electrophoretic pattern of proteins, plasmid DNA, and digested genomic DNA (in pulsed-field gel separation) were compared. Adansonian taxonomy yielded similarity clusters of the different isolates.
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PMID:Metabolic properties, stress tolerance and macromolecular profiles of rhizobia nodulating Hedysarum coronarium. 1524 61

Cell wall changes were examined in fruit of a melting flesh peach (Prunus persica L.) allowed to ripen on the tree. Three phases to softening were noted, the first of which began prior to the completion of flesh colour change and an increase in ethylene evolution. Softening in young mature fruit, prior to ripening, was associated with a depolymerization of matrix glycans both loosely and tightly attached to cellulose and a loss of Gal from all cell wall fractions. After the initiation of ripening, but before the melting stage, softening was associated with continuing, progressive depolymerization of matrix glycans. A massive loss of Ara from the loosely bound matrix glycan fraction was observed, probably from side chains of glucuronoarabinoxylan, pectin, or possibly arabinogalactan protein firmly bound into the wall and solubilized in this extract. An increase in the solubilization of polyuronides also occurred during this period, when softening was already well advanced. The extensive softening of the melting period was marked by substantial depolymerization of both loosely and tightly bound matrix glycans, including a loss of Ara from the latter, an increase in matrix glycan extractability, and a dramatic depolymerization of chelator-soluble polyuronides which continued during senescence. Depolymerization of chelator-soluble polyuronides thus occurred substantially after the increase in their solubilization. Ripening-related increases were observed in the activities of exo- and endo-polygalacturonase (EC 3.2.1.67; EC 3.2.1.15), pectin methylesterase (EC 3.1.1.11), endo-1,4-beta-glucanase (EC 3.2.1.4), endo-1,4-beta-mannanase (EC 3.2.1.78), alpha-arabinosidase (EC 3.2.1.55), and beta-galactosidase (EC 3.2.1.23), but the timing and extent of the increases differed between enzymes and was not necessarily related to ethylene evolution. Fruit softening in peach is a continuous process and correlated closely with the depolymerization of matrix glycans, which proceeded throughout development. However, numerous other cell wall changes also took place, such as the deglycosylation of particular polymers and the solubilization and depolymerization of chelator-soluble polyuronides, but these were transient and occurred only at specific phases of the softening process. Fruit softening and other textural changes in peach appear to have a number of stages, each involving a different set of cell wall modifications.
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PMID:Cell wall metabolism during maturation, ripening and senescence of peach fruit. 1528 50

Partially tree-ripened ripe fruit of peach (Prunus persica L.) were stored for 1-4 weeks at 5 degrees C and then ripened at 20 degrees C for 3 d to induce chilling injury. With increasing cold storage the incidence and severity of mealiness symptoms increased progressively, manifested as reduced quantities of free juice and internal flesh browning. Relative to juicy fruit, tissue of mealy fruit showed altered intercellular adhesion when examined by microscopy and, upon crushing, a higher proportion of cells remained intact and did not release cellular contents. Substantial alterations in the metabolism of cell wall polysaccharides were observed. Chelator-soluble polyuronides from mealy fruit were partially depolymerized during cold storage in a manner dissimilar to that in unripe or ripe juicy fruit, and were not depolymerized further during the ripening period. The solubility of these high molecular weight pectins remained low, and did not show the increase characteristic of juicy fruit. Furthermore, in mealy fruit the dramatic decline in the polymeric Ara content of base-soluble, matrix glycan-enriched fractions occurring during normal ripening was absent, indicating diminished disassembly of an arabinan-rich polysaccharide firmly attached to cellulose. A corresponding rise in the polymeric Ara content of the most soluble pectin fraction was also absent, as was a decline in the Gal content of this extract. The depolymerization of matrix glycans showed only minor differences between juicy and mealy fruit. After cold storage and ripening, the activities of endo-1,4-beta-glucanase (EC 3.2.1.4), endo-1,4-beta-mannanase (EC 3.2.1.78), beta-galactosidase (EC 3.2.1.23), alpha-arabinosidase (EC 3.2.1.55), and particularly endo-polygalacturonase (EC 3.2.1.15) were lower in mealy fruit than in juicy fruit, whereas pectin methylesterase activity (EC 3.1.1.11) was lower in slightly mealy and higher in very mealy fruit. The data suggest that cold storage affects the activities of numerous cell wall-modifying enzymes, with important consequences for pectin metabolism. These changes alter the properties of the primary wall and middle lamella, resulting in tissue breakage along enlarged air spaces, rather than across cells, which reduces the amount and availability of free juice upon tissue fragmentation.
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PMID:Cell wall metabolism during the development of chilling injury in cold-stored peach fruit: association of mealiness with arrested disassembly of cell wall pectins. 1531 Aug 20

Enzyme preparations were obtained from cell wall debris of tomato (Lycopersicon esculentum L. cv. Tropic) fruits at various stages of ripeness and were assayed for glycosidase and polysaccharidase activities. In addition to polygalacturonase (mol wt 40,000), ripening fruits contain beta-galactosidase (mol wt 63,000) and beta-1, 3-glucanase (mol wt 12,000). The beta-glycosidases, unlike polygalacturonase, are active in extracts of green fruits. Placental tissue shows very low polygalacturonase but increasing beta-galactosidase and beta-1, 3-glucanase activities as ripening proceeds. A large change in the susceptibility of the walls to hydrolase action occurs before the stage in which the greatest polygalacturonase activity occurs. The possibility that the beta-glycosidases contribute to the wall modifications that lead to fruit softening is discussed.
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PMID:Glycosidases in Cell Wall-degrading Extracts of Ripening Tomato Fruits. 1665 37

Changes in neutral sugar, uronic acid, and protein content of tomato (Lycopersicon esculentum Mill) cell walls during ripening were characterized. The only components to decline in amount were galactose, arabinose, and galacturonic acid. Isolated cell walls of ripening fruit contained a water-soluble polyuronide, possibly a product of in vivo polygalacturonase action. This polyuronide and the one obtained by incubating walls from mature green fruit with tomato polygalacturonase contained relatively much less neutral sugar than did intact cell walls. The ripening-related decline in galactose and arabinose content appeared to be separate from polyuronide solubilization. In the rin mutant, the postharvest loss of these neutral sugars occurred in the absence of polygalacturonase and polyuronide solubilization. The enzyme(s) responsible for the removal of galactose and arabinose was not identified; a tomato cell wall polysaccharide containing galactose and arabinose (6:1) was not hydrolyzed by tomato beta-galactosidase.
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PMID:Degradation of Cell Wall Polysaccharides during Tomato Fruit Ripening. 1666 Jun 60

Pectic polysaccharides from the roots of cucumber (Cucumis sativus L.) grown in liquid culture medium with or without calcium (1 mm CaCl(2)) were studied after extraction successively by hot water and Na hexametaphosphate solution. The Ca(2+) starvation-treatment caused a striking reduction in content of extracted pectic polysaccharide; from an equivalent weight of cell walls, only 33.1% of the control level was extracted from root cell walls of plants cultured under Ca(2+) deficiency. The extracted pectic polysaccharides were fractionated into neutral and acidic polymers by a DEAE-Sephadex column. The acidic polymers, which represented more than 76% of the yield, appeared to be a major fraction of extracted pectic polysaccharides. The changes of molecular size and glycosyl residue composition of this fraction were compared for the control and Ca(2+)-deprived samples. The results indicate that Ca(2+) deficiency caused structural changes which could involve both branching pattern and extent of contiguous galacturonosyl units in the water-solubilized pectic polysaccharides. Ca(2+) starvation also led to a notable decrease in molecular size of the hexametaphosphate-solubilized polysaccharides and, to a lesser extent, of the water-solubilized fraction as well. In addition, polygalacturonase activity in tissue homogenates increased remarkably with the Ca(2+) deficiency, whereas beta-galactosidase activity did not undergo a change. Thus, it appears that one major effect of Ca(2+) deprivation was to stimulate polygalacturonase activity, an effect which could be involved in the control of the breakdown of pectic polysaccharides in the cell walls.
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PMID:Pectic polysaccharide breakdown of cell walls in cucumber roots grown with calcium starvation. 1666 97

Pectic polysaccharides solubilized in vivo during ripening, were isolated using phenol, acetic acid, and water (PAW) from the outer pericarp of kiwifruit (Actinidia deliciosa [A. Chev.] C.F. Liang and A.R. Ferguson var deliciosa ;Hayward') before and after postharvest ethylene treatment. Insoluble polysaccharides of the cell wall materials (CWMs) were solubilized in vitro by chemical extraction with 0.05 molar cyclohexane-trans-1,2-diamine tetraacetate (CDTA), 0.05 molar Na(2)CO(3), 6 molar guanidinium thiocyanate, and 4 molar KOH. The Na(2)CO(3)-soluble fraction decreased by 26%, and the CDTA-soluble fraction increased by 54% 1 day after ethylene treatment. Concomitantly, an increase in the pectic polymer content of the PAW-soluble fraction occurred without loss of galactose from the cell wall. The molecular weight of the PAW-soluble pectic fraction 1 day after ethylene treatment was similar to that of the Na(2)CO(3)-soluble fraction before ethylene treatment. Four days after ethylene treatment, 60% of cell wall polyuronide was solubilized, and 50% of the galactose was lost from the CWM, but the degree of galactosylation and molecular weight of pectic polymers remaining in the CWMs did not decrease. The exception was the CDTA-soluble fraction which showed an apparent decrease in molecular weight during ripening. Concurrently, the PAW-soluble pectic fraction showed a 20-fold reduction in molecular weight. The results suggest that considerable solubilization of the pectic polymers occurred during ripening without changes to their primary structure or degree of polymerization. Following solubilization, the polymers then became susceptible to depolymerization and degalactosidation. Pectolytic enzymes such as endopolygalacturonase and beta-galactosidase were therefore implicated in the degradation of solubilized cell wall pectic polymers but not the initial solubilization of the bulk of the pectic polymers in vivo.
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PMID:Cell Wall Dissolution in Ripening Kiwifruit (Actinidia deliciosa) : Solubilization of the Pectic Polymers. 1666 51


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