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At least 649 records · Page 36Linked to original sources
PubMed2006

A new group of exo-acting family 28 glycoside hydrolases of Aspergillus niger that are involved in pectin degradation.

The fungus Aspergillus niger is an industrial producer of pectin-degrading enzymes. The recent solving of the genomic sequence of A. niger allowed an inventory of the entire genome of the fungus for potential carbohydrate-degrading enzymes. By applying bioinformatics tools, 12 new genes, putatively encoding family 28 glycoside hydrolases, were identified. Seven of the newly discovered genes form a new gene group, which we show to encode exoacting pectinolytic glycoside hydrolases. This group includes four exo-polygalacturonan hydrolases (PGAX, PGXA, PGXB and PGXC) and three putative exo-rhamnogalacturonan hydrolases (RGXA, RGXB and RGXC). Biochemical identification using polygalacturonic acid and xylogalacturonan as substrates demonstrated that indeed PGXB and PGXC act as exo-polygalacturonases, whereas PGXA acts as an exo-xylogalacturonan hydrolase. The expression levels of all 21 genes were assessed by microarray analysis. The results from the present study demonstrate that exo-acting glycoside hydrolases play a prominent role in pectin degradation.

Acetylesterase↗
PubMed2001

Characterization of pectin lyase produced by an endophytic strain isolated from coffee cherries.

AIMS: The effect of endophytic bacterial activity on the quality of coffee beverage was studied. METHODS AND RESULTS: A survey of the micro-organisms in coffee cherries was performed before harvesting, and their growth on the main nutrients available in coffee cherries was determined in vitro. CONCLUSION: Many endophytic bacteria were isolated from surface-sterilized coffee cherries. One of the pectinolytic strains was physiologically and phenotypically characterized, and was tentatively identified by partial 16S rDNA sequencing as Paenibacillus amylolyticus. This endophytic strain produced an extracellular pectinase with maximal activity at 40 degrees C and pH 7.9, and was thermostable up to 45 degrees C. EDTA and metal ions had little effect on pectin lyase activity. Km and Vmax values were 4.6 mg ml(-1) and 94.0 10(-8) mol min(-1) ml(-1), respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: Pectin lyases have been found in fungi but rarely in bacteria, and this isolate is a promising tool for regulation studies of these enzymes.

Bacillaceae↗
PubMed1999

Pectins and xyloglucans exhibit antimutagenic activities against nitroaromatic compounds.

Because a high daily consumption of polysaccharides-containing food is assessed to decrease the risk of cancer of the gastrointestinal system, different types of carbohydrates were investigated for their antimutagenic activity against different standard mutagens. Within the screening pronounced antimutagenic effects were found for xyloglucan and different pectins and pectin-like rhamnogalacturonans against 1-nitropyrene induced mutagenicity. Inhibition rates were dose-dependent and varied between 20 and 50%. Concerning the mode of action a direct interaction of the polymers with the cells is claimed, protecting the organisms from the mutagenic attack.

Anticarcinogenic Agents↗
PubMed2002

A pectin glucuronyltransferase gene is essential for intercellular attachment in the plant meristem.

Intercellular attachment is an essential process in the morphogenesis of multicellular organisms. A unique mutant, nolac-H18 (nonorganogenic callus with loosely attached cells), generated by T-DNA transformation using leaf-disk cultures of haploid Nicotiana plumbaginifolia, lost the ability to form tight intercellular attachments and adventitious shoots. The gene tagged with T-DNA, named NpGUT1 (glucuronyltransferase 1), was similar to the gene for the catalytic domains of animal glucuronyltransferases and was expressed predominantly in shoot and root apical meristems. The transformation of NpGUT1 complemented the nolac-H18 mutation, and the expression of antisense NpGUT1 RNA produced crumbled shoots. The mutation caused defects in the glucuronic acid of rhamnogalacturonan II of pectin, which drastically reduced the formation of borate cross-linking of rhamnogalacturonan II. NpGUT1, which encodes a unique glucuronyltransferase, is a glycosyltransferase gene identified in pectin biosynthesis and is essential for intercellular attachment in plant meristems and tissues.

Amino Acid Sequence↗
PubMed1983

Differing effects of pectin, cellulose and lignin on stool pH, transit time and weight.

Randomized cross-over studies were undertaken to determine the effects of daily dietary supplements of pectin (12 g/d), cellulose (15 g/d) and lignin (12 g/d) on stool characteristics of healthy volunteers. Detailed dietary records were kept throughout the study. Stool collections over 48 h were used to determine mean stool pH and weight. The single stool transit time was measured using radio-opaque markers. Pectin did not significantly alter the mean stool pH, transit time or 24 h wet weight. Cellulose lowered the mean stool pH from 6.38 to 6.12, decreased mean stool transit time by 27% and increased mean wet stool weight by 57%. Lignin lowered the mean pH from 6.34 to 6.25, decreased the stool transit time by 20% and increased stool weight by 27% but these changes were not statistically significant. These findings have shown that individual fibre components have different colonic metabolic effects and support the view that associations between dietary fibre intakes and diseases such as colorectal cancer should be evaluated with regard to the type of fibre components consumed.

Adult↗
PubMed1988

Degradation of hemicellulose and pectin by horse caecum contents.

1. Polysaccharide depolymerases and glycoside hydrolases involved in the breakdown of plant structural polysaccharides (hemicellulose and pectins) were monitored in three fractions of the liquid phase of horse caecum digesta: acellular fluid (AF), bacteria (B) and protozoa plus bacteria (PB). 2. Both bacteria and protozoa were found to be involved in the decomposition of pectic substances, with two enzymic activities: depolymerase (polygalacturonase, EC 3.2.1.15; and pectin lyase, EC 4.2.2.10) and esterase (pectinesterase, EC 3.1.1.11). The activity of the PB fraction was higher than that of B. 3. With hemicellulosic substrates, all three fractions showed a significant xylan endo-1,3-beta-xylosidase (EC 3.2.1.32) activity. Mannan was hardly broken down. 4. Galactomannan and arabinogalactan were broken down more extensively by the PB fraction than by the B fraction. Glycosidase activities (xylan 1,4-beta-xylosidase, EC 3.2.1.37 and alpha-L-arabinofuranosidase, EC 3.2.1.55) were also observed.

Animals↗
PubMedDate not supplied

Adjuvant properties of polysaccharides: effect of iota-carrageenan, pectic acid, pectin, dextran and dextran sulphate on the humoral immune response in the rat.

Iota-carrageenan can both enhance agglutinating antibody responses and trigger reaginic antibody production against a protein associated antigen in rats. The present study investigates the strain specificity of this phenomenon and compares the adjuvanticity of high and low molecular weight iota-carrageenan with a series of structurally distinct polysaccharides (pectin, pectic acid, dextran and dextran sulphate). Using ovalbumin as the test antigen, high molecular weight iota-carrageenan induced a potent ovalbumin specific reaginic antibody response in PVG and Hooded Lister strain rats, an intermediate response in Sprague Dawley rats and a weak response in DA, AO and F344 strain rats. Further studies in PVG rats revealed that the nature and magnitude of the antibody response induced was influenced by the type of polysaccharide carrier used. Thus, whereas, high molecular weight carrageenan enhanced the agglutinating antibody (agglutinin) response and simultaneously elicited de novo reaginic antibody production to co-administered ovalbumin, low molecular weight carrageenan facilitated reaginic antibody production but had no effect on the agglutinin response. Pectin and dextran had no effect on the agglutinin response and failed to elicit reaginic antibody production. Conversely, pectic acid and dextran sulphate enhanced the agglutinin response and elicited a transient reaginic anti-ovalbumin response.

Adjuvants, Immunologic↗
PubMed1991

[The energetic utilization of rations with dried concentrates, potatoes, sugar beets, apple pectin and cane sugar by growing, intact and ileorectostomized swine. 1. Results in swine with ileorectal anastomoses].

Rations with dried feedstuffs and rations with between 30 and 50% raw potatoes in the dry matter as well as steamed potatoes and sugar beets, sucrose and apple pectin were tested in measurings of the total metabolism in growing pigs with ileo-rectal anastomoses. The prececal digestibility of the energy of the rations ranged between 42% (rations with raw potatoes) and 79% (rations with sucrose). The digestibility of the rations with a 50% quota of steamed potatoes was better by 30%--units than that of rations with raw potatoes. In addition to crude nutrient digestibility, data are given on the digestibility of starch, water soluble carbohydrates and pectin. The wide variation in the N retention of 6-25 g/animal.day can only be partly connected with energy retention. Urine energy amounted to between 2.5 and 5% of gross energy. The average utilization of metabolizable energy amounted to 69.4%. A connection is to be seen with the value of energy maintenance requirement of 646 kJ retention energy/kg LW0.62.d.

Anastomosis, Surgical↗
PubMed1991

[The energetic utilization of rations with dried concentrates, potatoes, sugar beets, apple pectin and cane sugar by growing, intact and ileorectostomized swine. 2. Comparison of results].

Results of the measuring of the total metabolism of growing intact pigs (INT) and pigs with ileorectal anastomoses (IRA) are compared. The 16 comparisons are based on studies with rations of dried feedstuffs and rations containing between 30 and 50% of the DM raw or steamed potatoes and sugar beets, sucrose and apple pectin. On an average of all comparisons the relative values for the digestibility of energy, DM and the organic matter as well as for the metabolizability of the energy were between 81 and 82% (values measured at INT animals = 100). The comparison also refers to the crude nutrients, the water-soluble carbohydrates, the starch and the pectin. As a tendency, the IRA utilized the metabolizable energy better than the INT animals. The energy maintenance requirement of the IRA animals was--by 15%--significantly higher than that of the INT animals. There is not yet an answer to the question in how far comparative studies of INT and IRA animals make verified statements with regard to the differences in the energetic utilization of the precaecally and postileally digested nutrients possible. For this, further experiments will be necessary.

Anastomosis, Surgical↗
PubMed2005

Calcium pectinate capsules for colon-specific drug delivery.

The calcium pectinate (CaP) capsule, a novel, colon-specific delivery system, was designed and developed using 5-fluorouracil (5-FU) as a model drug. Technically, CaP capsules were prepared by dipping a glass or stainless steel rod successively into pectin and calcium chloride solutions, followed by subsequent air-drying and coating. In vitro studies showed that the release of 5-FU from CaP capsules markedly increased in the presence of rat cecal contents, and the release characteristic was mainly associated with some capsule parameters such as calcium content, shell thickness, and coat amount. Gamma scintigraphic studies demonstrated that CaP capsules could pass through the stomach and small intestine intact and could release drug in colon. The 5-FU releasing characteristics acquired both from in vitro biomimic dissolution experiments and from healthy volunteers indicated that the newly developed CaP capsule possessed the ideal colon-specific drug delivery characteristic.

Administration, Oral↗
PubMed1977

Effect of citrus pectin on blood lipids and fecal steroid excretion in man.

Citrus pectin (15 g/day) was added for 3 weeks to metabolically controlled diets in nine subjects. Pectin was consumed with fruit and sugar as a gel in divided doses with meals. Plasma cholesterol concentrations were reduced by a mean of 13% (P less than 0.001). Fecal fat excretion increased by 44% (P less than 0.001); neutral steroids by 17% (P less than 0.001) and fecal bile acids by 33% (P less than 0.02). Plasma triglyceride levels did not change.

Adult↗
PubMed1985

The effects of the fiber components pectin, cellulose and lignin on serum cholesterol levels.

Eight-week randomized cross-over studies in three separate groups of 10 healthy volunteers were undertaken to determine the effects of daily dietary supplementation with pectin (12 g/day), cellulose (15 g/day) and lignin (12 g/day) on serum lipid levels. Detailed dietary records were kept throughout the study and there was no significant change in dietary intakes except for the fiber supplement. Neither pectin, cellulose, nor lignin significantly altered serum total cholesterol, triglycerides, high-density lipoprotein cholesterol, or the ratio of high-density lipoprotein to total cholesterol in healthy normolipidemic subjects over four weeks.

Adult↗
PubMed1995

Site specific reduction of colon cancer incidence, without a concomitant reduction in cryptal cell proliferation, in 1,2-dimethylhydrazine treated rats by diets containing 10% pectin with 5% or 20% corn oil.

The effects of specific dietary interventions on incidence of carcinogen-induced cancer and on cryptal cell proliferation in areas of the colon located either over aggregates of lymphoid nodules (ALN) or away from ALN was investigated. Groups of dimethylhydrazine (DMH) treated rats or non-DMH-treated rats were fed a basal AIN-76 diet less fiber of any type, or the basal fiber free diet supplemented with 10% pectin and with 5%, 10%, or 20% corn oil. The adenocarcinoma (AC) incidence was determined in regions of the colon, i.e. ascending, descending, descending over the ALN and descending away from the ALN. The results indicate that: (i) factors associated with ALN promote AC formation, (ii) dietary modifications (addition of pectin and of 20% corn oil to the diet) each cause significant site specific suppression of AC incidence, (iii) DMH-treatment rendered crypts non-responsive to the suppression of cryptal cell proliferation which occurred in the rats not treated with DMH (suggestive of a DMH-induced loss in the regulation of cell proliferation) and (iv) reduction of AC incidence was not always accompanied by reduction in crypt cell proliferation. Studies of intervention procedures designed to prevent colon cancer should take into account the colon site specific tumorigenic response to the preventive agent and should not rely on a single biomarker to predict the efficacy of the intervention.

Animals↗
PubMed1982

Effects of dietary cellulose, pectin and oat bran on the small intestine in the rat.

The present study was undertaken to determine if three sources of dietary fiber would alter length, weight, DNA, protein or enzyme activity in the small intestine since various fibers are known to decrease intestinal absorption. Rats were fed semipurified diets that contained either 20% cellulose (C), 20% oat bran, 5% pectin (P) or no fiber source (FF). Leucine aminopeptidase activity were significantly greater in the P and C groups when compared with the FF group. There were no significant differences in sucrase activity. Animals in the P group had heavier and longer small intestine and heavier mucosa than the FF group. There were no significant differences in total mucosal DNA or protein. These results indicate that two sources of dietary fiber, cellulose and pectin, can change leucine aminopeptidase activity in the small intestine.

Animals↗
PubMed1985

Effect of wheat bran, pectin and cellulose on the secretion of bile lipids in rats.

We assayed the lipid content of bile from rats that had been fed either a standard diet (5% fat) or a high fat diet (25% fat, 1.2% cholesterol) in the presence or in the absence of various dietary fibers (namely, wheat bran, pectin and cellulose). The cholesterol concentration in bile from rats fed the high fat diet plus wheat bran or pectin was lower than that of the rats fed the high fat, high cholesterol diet without fiber. Bile phospholipids did not vary significantly from one group to another. In comparison to the standard diet, the high fat, high cholesterol diet led to a greater ratio of primary to secondary bile salts and a higher level of glycoconjugates. The observed differences may be explained by a variation in the metabolism of bile salts brought about by the difference in diet.

Animals↗
PubMed1990

Pectin isolated from prickly pear (Opuntia sp.) modifies low density lipoprotein metabolism in cholesterol-fed guinea pigs.

The effect of prickly pear soluble fiber on low density lipoprotein (LDL) metabolism was investigated by feeding male guinea pigs either a nonpurified diet containing 0.25% cholesterol (HC diet) or the HC diet + 1% prickly pear pectin (HC-P diet). Plasma cholesterol levels were significantly decreased by the HC-P diet, with a 33% decrease in LDL levels (p less than 0.02) and an increase in LDL density. Hepatic free and esterified cholesterol levels were reduced 40 and 85%, respectively (p less than 0.002), by the HC-P diet. Hepatic microsomal 3-hydroxy-3-methylglutaryl coenzyme A reductase levels were not different. 125I-LDL binding to hepatic membranes was increased 1.7-fold by the HC-P diet (p less than 0.001), with receptor affinity (Kd) being unaltered and receptor number (Bmax) being significantly increased (p less than 0.001). These data suggest that prickly pear pectin may act by a mechanism similar to that of bile acid-binding resins in lowering plasma cholesterol levels. The observed reduction in LDL and hepatic cholesterol levels and increase in LDL density and hepatic apolipoprotein B/E receptors are responses suggesting an increased demand on hepatic cholesterol from increased excretion of bile acids and interruption of the enterohepatic circulation.

Administration, Oral↗
PubMed2003

Apple pectin and a polyphenol-rich apple concentrate are more effective together than separately on cecal fermentations and plasma lipids in rats.

To evaluate the effect of apple components on cecal fermentations and lipid metabolism, rats were fed diets containing 5 g/100 g apple pectin (PEC), 10 g/100 g high polyphenol freeze-dried apple (PL) or both (PEC + PL). The cecal pH was slightly acidic (6.49) only in rats fed the PEC + PL diet (controls, 7.02). The cecal short-chain fatty acid pool was enlarged by all the apple fractions, with a peak of 560 micromol in rats fed the PEC + PL diet compared with 189 micromol in controls. Butyrate concentrations were 2-fold greater in rats fed the PL diet than in controls. Substantial concentrations of galacturonate and succinate (approximately 40 mmol/L) were found in the cecum of rats fed the PEC diet and, to a lesser extent, the PEC + PL diet. The PEC + PL diet significantly lowered plasma cholesterol, whereas both the PL and PEC + PL diets lowered plasma triglycerides. Liver cholesterol and triglyceride concentrations were lower in rats fed the PEC and PEC + PL diets. Fecal bile acid excretion was markedly reduced, whereas sterol excretion was significantly increased by dietary PEC. Rats fed the PEC and PEC + PL diets also had lower apparent cholesterol absorption than controls (30 compared with 43%). In conclusion, apple pectin and the polyphenol-rich fraction were more effective when fed combined together than when fed separately on large intestine fermentations and lipid metabolism, suggesting interactions between fibers and polyphenols of apple.

Animals↗
PubMed2005

Lygodium japonicum fern accumulates copper in the cell wall pectin.

The present work reports the results of a study on the growth kinetics and characterization of matrix polysaccharides in the cell walls of Lygodium japonicum prothallium grown in the presence of copper (Cu). When the prothallium was cultured in the media containing 0.2 mM or 0.4 mM CuSO(4), it showed a rapid accumulation of Cu with a maximum uptake of Cu measured in the cells up to 20 d of culture. The maximum rate of Cu uptake into the prothallium was greater for 0.4 mM Cu-treated cells (17.2 micromol g(-1) DW) than for 0.2 mM Cu-treated cells (3.2 micromol g(-1) DW). Cell walls were isolated from both untreated control and Cu-treated cells and then extracted sequentially with cyclohexane-trans-1,2-diaminetetra-acetate (CDTA), Na(2)CO(3), 1 M KOH, and 4 M KOH. The amount of pectin solubilized from 0.4 mM Cu-treated cell walls decreased to 53% of its level in the control, whereas the amount of hemicellulose solubilized from the Cu-treated cell walls represented 82% of that from control cell walls. When the polysaccharides were fractionated by anion-exchange chromatography into four carbohydrate components, considerable increases in fractions PI-3 and PII-3 eluted with 0.5 M NaCl were observed in CDTA-soluble (PI) and Na(2)CO(3)-soluble (PII) pectic polymers from Cu-treated cell walls. Fractions PI-3 and PII-3 were composed predominantly of uronic acid (more than 71% of total sugars). Approximately 66% of Cu within the cell walls was released from the 0.4 mM Cu-treated cells with the endo-pectate-lyase treatment, suggesting that most of the Cu that accumulated into the Lygodium prothallium is tightly bound to the homogalacturonan of the cell wall pectin.

Biological Transport, Active↗