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PubMedDate not supplied

[Evaluation of a pectin with a low degree of esterification as a prophylactic agent in lead poisoning].

In experiments with rats, which were undergoing priming by mouth with an acetic lead solution at the rate of 6 mg/day for 1 1/2 month, the prophylactic effect of apple pectin esterified to the degree of 26 per cent (doses 36 and 72 mg) and of 32 per cent (doses of 216 and 432 mg) was evaluated. The best prophylactic effect was found to produce pectin with a 32 per cent esterification degree, but in some of rats dysfunction of the gastro-intestinal tract was noted.

Animals↗
PubMed1980

A double-blind study on the effects of differing purified cellulose and pectin fiber diets on 1,2-dimethylhydrazine-induced rat colonic neoplasia.

The incidence, distribution, size, and histopathology of colonic tumors induced by parenteral administration of 1,2-dimethylhydrazine were examined in rats fed a chemically defined fiber-free diet or nutritionally and calorically equivalent diets containing either 4.5 or 9.0% purified cellulose or pectin. This double-blind study indicates that cellulose is protective against experimental colonic neoplasia. Although the precise mechanism for this protective effect remains to be elucidated, it was not cellulose dose dependent and appeared to depend on administration during injection of carcinogen. Furthermore, this study provides strong evidence that identical amounts of cellulose and pectin fed as the sole source of fiber in chemically defined diets exert strikingly different effects in relation to development of intestinal neoplasia in this animal model.

Adenocarcinoma↗
PubMed1982

[Serum lipid studies of hyperlipoproteinemia patients during diet therapy with pectin preparations].

Seventy one patients with nutritional-metabolic obesity (II--IV degree) were examined, with or without hyperlipoproteinemia, treated in hospitals or sanatoria for 25 days. The effect of the hypoenergy diet regimen (5,94 kJ = 1460 cal) was studied, that was combined with an average daily import of 11 g esterified, apple pectin (in fruit pastes and drinks) upon the level of 6 serum lipid indices. A decrease (less than 0,05) of total cholesterol, triglycerides and some other lipid indices was established both in the patients with hyperlipoproteinemia type II (IIa and IIb) and type IV, in those without hyperlipoproteinemia syndrome as well. Due to the hypolipidemic effect established the newly produced articles with high esterified apple pectin are recommended in the complex treatment of the patients with obesity (with or without secondary hyperlipoproteinemeia.

Adult↗
PubMedDate not supplied

[Methane formation from pectin by a combined Clostridium pectinofermentans and Methanosarcinia vacuolata culture].

The combined culture of Clostridium pectinofermentans and Methanosarcina vacuolata was shown to be capable of methane production from pectin. Hydrogen, methanol and acetate were methane precursors in that case. C. pectinofermentans grew by 67% better in the combined culture comparing to the pure culture. The stimulating action of M. vacuolata cannot be attributed to the elimination of methanol since it has no effect on the growth of C. pectinofermentans on pectin.

Anaerobiosis↗
PubMed1995

Adhesive tape vs pectin-based barrier use in preterm infants.

This controlled trial studied 20 premature infants, 28-33 weeks of gestational age, over 21 days. It compared the gross skin condition on the side of the face where tape was applied directly to the skin to anchor a nasogastric tube to the other side, where the tape was applied over a pectin-based barrier. Ninety-four percent of the infants had no gross signs of skin breakdown on the side under the barrier for as long as 21 days. In contrast, 80 percent of the same infants had gross signs of skin breakdown within five days on the side of the face where the tape was applied directly to the skin. The results indicate that a pectin-based barrier should be applied when tape must be used to anchor equipment in premature infants.

Adhesives↗
PubMed1994

Pulsed field gradient spin-echo NMR measurement of water diffusion coefficient in thickening and gelling agents: guar galactomannan solutions and pectin gels.

The Pulsed Field Gradient Spin-Echo (PFG-SE) method was used to study the diffusional properties of water in guar galactomannan solutions and in highly methyl-esterified (HDE) pectin solutions and gels. The diffusion coefficient of water in the non-gelling galactomannan system was the same than that of pure water and independent on polymer concentration, despite of a strong increase in viscosity. In the two-component gelling system, pectin-sucrose, the diffusion coefficient of water was lower than in the pure state, and decreasing as a function of the concentration of both constituents. A normalized diffusion coefficient, Dgel/Dsuc, was defined to discriminate the effect of the gelation process on water diffusion, and it showed a clear dependence on the extent of network formation. Unrestricted diffusion was evidenced in all cases.

Diffusion↗
PubMed1997

[Antimicrobial properties of pectins and their effects on antibiotics].

The influence of food fibres and plant proteins on microorganisms, bacteriophages, antibiotics and penicillinase was studied in vitro. It was shown that pectin was the only agent that had a bactericidal effect on the most widely distributed pathogenic and opportunistic microorganisms and did not influence indigenic microflora. High concentrations of pectin (> 2 per cent) had an inactivating effect on therapeutic bacteriophages. There was also a decrease in the antimicrobial activity of penicillins. The other agents tested i.e. wheat bran, soya isolate and soybean flour had no influence on microorganisms, bacteriophages and antibiotics. No sorption activity of the food fibres and plant proteins with respect to microorganisms and antibiotics or their effect on penicillinase was observed.

Anti-Bacterial Agents↗
PubMed1998

Hypolipidemic mechanisms of pectin and psyllium in guinea pigs fed high fat-sucrose diets: alterations on hepatic cholesterol metabolism.

Studies were conducted to determine whether pectin (PE) or psyllium (PSY) could reverse the high plasma cholesterol and triacylglycerol (TAG) concentrations induced by high fat (HF) or high sucrose (HS) diets and which are the mechanisms involved. Male guinea pigs were fed either a low fat (LF) or a HF diet with 80% of the carbohydrate energy derived from sucrose. Cellulose was used as control. Plasma LDL cholesterol, TAG, apolipoprotein B, and hepatic cholesteryl ester were lower in guinea pigs fed PE and PSY compared to the control group (P < 0.03). In addition, a 45% higher number of hepatic apoB/E receptors was observed by PE and PSY intake. Hepatic ACAT, HMG-CoA reductase, and cholesterol 7alpha-hydroxylase (C7H) activities were higher in the HF compared to the LF groups (P < 0.01). PSY intake with HF resulted in up-regulation of C7H and HMG-CoA reductase activities (P < 0.05). Additional studies measuring the effects of PE and PSY on low density lipoprotein (LDL) transport and very low density lipoprotein (VLDL) secretion were conducted in the HF groups. ApoB secretion was reduced by pectin and psyllium (P < 0.01) intake while LDL fractional catabolic rates were 100% faster in guinea pigs fed PE or PSY. In these studies the extent of the hypolipidemic response was specific to each fiber type and associated with the amount of sucrose. In addition, PSY altered the activity of hepatic enzymes of cholesterol homeostasis in the HF group. These additional effects of PSY might explain the more dramatic changes in plasma lipid levels associated with PSY consumption.

Animals↗
PubMed2002

Electrophysiological analysis of synaptic interactions within peg sensilla of scorpion pectines.

Pectines are unique, midventral sensory appendages that help direct mating and food-finding behaviors in scorpions. Dense two-dimensional arrays of bimodally sensitive (chemical and mechanical) peg sensilla form the primary sensory structures on pectines. Several qualities of peg sensilla make them well suited to electrophysiological investigation, including accessibility, stability of extracellular recordings, and the ease with which spiking cells can be identified and categorized. Cross-correlations of spontaneous neural activity show signs of synaptic interactions between sensillar neurons in all species examined to date (Paruroctonus mesaensis, Hadrurus arizonensis, Centruroides vittatus) representing three families and two superfamilies. Both excitatory and inhibitory interactions have been observed, as well as possible dyadic synaptic arrangement. Computer simulations of cross-correlograms are consistent with experimental data and may help provide additional insight into functionality of synaptic connections. Intra-sensillar interactions, coupled with the topographic order of peg sensilla and their central nervous system projections, may allow scorpions to precisely resolve microfeatures of chemical stimuli. Future research directions include inter-sensillar recordings to determine whether synaptic interactions extend between adjacent sensilla. Other unresolved questions that can be approached electrophysiologically are whether mechanosensory cells interact with chemosensitive cells and how the synaptic circuits function under specific chemical and mechanical stimulation.

Animals↗
PubMed2003

Tomato pectin methylesterase: modeling, fluorescence, and inhibitor interaction studies-comparison with the bacterial (Erwinia chrysanthemi) enzyme.

The molecular model of Lycopersicon esculentum (tomato) pectin methylesterase (PME) was built by using the X-ray crystal structure of PME from the phytopathogenic bacterium Erwinia chrysanthemi as a template. The overall structure and the position of catalytically important residues (Asp132, Asp 153, and Arg 221, located at the bottom of the active site cleft) are conserved. Instead, loop regions forming the walls of the catalytic site are much shorter and form a less deep cleft, as already revealed by the carrot PME crystal structure. The protein inhibitor of pectin methylesterase (PMEI) isolated from kiwi fruit binds tomato PME with high affinity. Conversely, no complex formation between the inhibitor and PME from E. chrysanthemi is observed, and the activity of this enzyme is unaffected by the presence of the inhibitor. Fluorescence quenching experiments on tomato PME and on PME-PMEI complex suggest that tryptophanyl residues present in the active site region are involved in the interaction and that the inhibitor interacts with plant PME at the level of the active site. We also suggest that the more open active site cleft of tomato PME allows the interaction with the inhibitor. Conversely, the narrow and deep cleft of the active site of E. chrysanthemi PME hinders this interaction. The pH-dependent changes in fluorescence emission intensity observed in tomato PME could arise as the result of protonation of an Asp residue with unusually high pKa, thus supporting the hypothesis that Asp132 acts as acid/base in the catalytic cycle.

Amino Acid Sequence↗
PubMed1996

A continuous fluorometric assay for pectin methylesterase.

A continuous, fluorometric assay for pectin methylesterase (PME) activity is described. In this assay, methanol produced by PME hydrolysis of pectin methyl esters is oxidized to formaldehyde by alcohol oxidase, and the formaldehyde is continuously reacted with 4-amino-3-penten-2-one to create a stable, fluorescent product. The increase in fluorescence intensity is linearly proportional to PME activity. The assay can be used in crude plant or fungal extracts with relatively little interference with chemicals or buffers commonly used in PME purification. The fluorescence assay has a useful pH range, from pH 5.0 to 6.5, which overlaps pH optima for many bacterial and fungal PMEs, but which limits its usefulness in assaying plant PMEs with alkaline pH optima. Nevertheless, the method is valuable for rapid assay of plant PMEs during their purification or for comparison of plant tissue PME activities.

Carboxylic Ester Hydrolases↗
PubMed2002

Gel diffusion assays for endo-beta-mannanase and pectin methylesterase can underestimate enzyme activity due to proteolytic degradation: a remedy.

The accuracy of the sensitive gel-diffusion assay for endo-beta-mannanase activity was improved when protein was added to fruit extracts or into the substrate-gel matrix in which the enzyme assays were conducted. Mixing of commercially available protease inhibitors with fruit enzyme extracts also resulted in increased assayable activity. These treatments were less effective when applied to extracts from tomato seeds, which contained over three times more endogenous protein than fruit extracts. Thus the presence of added or higher amounts of endogenous proteins served as the protectant for endo-beta-mannanase during the course of the gel-diffusion assay, which required an incubation at 32 degrees C for at least 18 h. There was no difference in assayable endo-beta-mannanase activity in the presence and absence of added protein when measured rapidly by viscometry. An effective modification was made to the galactomannan substrate gel assay for endo-beta-mannanase, which is the most efficient method for assaying large numbers of extracts, to improve its accuracy when the enzyme is obtained from tissues containing a low endogenous protein content. This involved incorporating an optimal concentration of gelatin into the galactomannan assay matrix gel. Much higher enzyme activities were recorded, with up to a 10-fold increase for tomato fruit extracts, compared to the same samples assayed on gels with no gelatin added. This increased activity was also obtained using extracts from the fruit of cantaloupe, peach, and nectarine. When incorporated into esterified pectin substrate gels, gelatin also increased the assayable activity of pectin methylesterase. Thus the incorporation of protein (gelatin) into substrate gels during the assay also should be widely more useful for other cell-wall-mobilizing enzymes and hydrolases.

Binding, Competitive↗
PubMed2000

Expression of a Petunia inflata pectin methyl esterase in Solanum tuberosum L. enhances stem elongation and modifies cation distribution.

Transgenic potato (Solanum tuberosum L.) plants were constructed with a Petunia inflata-derived cDNA encoding a pectin methyl esterase (PME; EC 3.1.1.11) in sense orientation under the control of the cauliflower mosaic virus 35S promoter. The PME activity was elevated in leaves and tubers of the transgenic lines but slightly reduced in apical segments of stems from mature plants. Stem segments from the base of juvenile PME-overexpressing plants did not differ in PME activity from the control, whereas in apical parts PME was less active than in the wild-type. During the early stages of development stems of these transgenic plants elongated more rapidly than those of the wild-type. Further evidence that overexpression of a plant-derived PME has an impact on plant development is based on modifications of tuber yield, which was reduced in the transgenic lines. Cell walls from transgenic tubers showed significant differences in their cation-binding properties in comparison with the wild-type. In particular, cell walls displayed increased affinity for sodium and calcium, while potassium binding was constant. Furthermore, the total ion content of transgenic potatoes was modified. Indications of PME-mediated differences in the distribution of ions in transgenic plants were also obtained by monitoring relaxations of the membrane potential of roots subsequent to changes in the ionic composition of the bathing solution. However, no effects on the chemical structure of pectin from tuber cell walls could be detected.

Carboxylic Ester Hydrolases↗
PubMed2004

Pectin methylesterase inhibitor cDNA from kiwi fruit.

We have newly isolated one partial pectin methylesterase inhibitor (PMEI) and two full-length cDNA clones from a kiwi fruit cDNA library. The two full-length cDNA clones, Adpmei-1 and Adpmei-2, had an open reading frame of 185 amino acids, including a predicted signal peptide sequence necessary for localization in the cell-wall space. As the deduced amino acid sequence of the cloned fragment was almost same as the sequence of the previously purified PMEI protein (Camardella et al., Eur J Biochem 267:4561-4565), the clones were considered to be cDNAs encoding PMEI protein. Southern blot analysis indicated a low-copy number of the PMEI genes. Transgenic analysis of asparagus calli expressing a kiwi fruit PMEI gene driven by the CaMV 35S promoter demonstrated in vivo inhibition effects of PMEI on the endogenous pectin methylesterase (PME) activity. The relative expression levels of the PMEI genes in kiwi fruit, analyzed by competitive PCR, increased with the progression of fruit maturation. Given that PME activity also showed its highest level at the fully ripened stage of maturation, the increase in PMEI expression may not indicate direct inhibitory effects on the PME activity and fruit maturation process.

Actinidia↗
PubMed2004

Inhibition of a ubiquitously expressed pectin methyl esterase in Solanum tuberosum L. affects plant growth, leaf growth polarity, and ion partitioning.

Two pectin methyl esterases (PMEs; EC 3.1.1.11) from Solanum tuberosum were isolated and their expression characterised. One partial clone ( pest1) was expressed in leaves and fruit tissue, while pest2 was a functional full-length clone and was expressed ubiquitously, with a preference for aerial organs. Potato plants were transformed with a chimeric antisense construct that was designed to simultaneously inhibit pest1 and pest2 transcript accumulation; however, reduction of mRNA levels was confined to pest2. The decrease in pest2 transcript was accompanied by up to 50% inhibition of total PME activity, which was probably due to the reduction of only one PME isoform. PME inhibition affected plant development as reflected by smaller stem elongation rates of selected transformants when compared with control plants, leading to a reduction in height throughout the entire course of development. Expansion rates of young developing leaves were measured simultaneously by two displacement transducers in the direction of the leaf tip (proximal-distal axis) and in the perpendicular direction (medial-lateral axis). Significant differences in leaf growth patterns were detected between wild-type and transgenic plants. We suggest that these visual phenotypes could be correlated with modifications of ion accumulation and partitioning within the transgenic plants. The ion-binding capacities of cell walls from PME-inhibited plants were specifically modified as they preferentially bound more sodium, but less potassium and calcium. X-ray microanalysis also indicated an increase in the concentration of several ions within the leaf apoplast of transgenic plants. Moreover, quantification of the total content of major cations revealed differences specific for a given element between the leaves of PME-inhibited and wild-type plants. Reduced growth rates might also be due to effects of PME inhibition on pectin metabolism, predominantly illustrated by an accumulation of galacturonic acid over other cell wall components.

Carboxylic Ester Hydrolases↗
PubMed2004

Identification and isolation of a pectin methylesterase isoform that could be involved in flax cell wall stiffening.

Pectin methylesterases (PMEs) are ubiquitous enzymes present in the plant cell wall. They catalyse the demethylesterification of homogalacturonic acid units of pectins, which, in turn, can be associated with different physiological phenomena. In this study, different flax (Linum usitatissimum L.) PME isoforms were observed: neutral (pI 7.0 and 7.5, MW: 110 kDa), basic (pI 8.3 and 8.5, MW: 110 kDa) and very basic (pI>9.5, MW: 38 kDa). In an attempt to identify most of the expressed cell wall LuPME isoforms, polyclonal antibodies were raised against a conserved region of PME. These antibodies allowed the purification of the very basic PME isoform (pI 9.5, MW: 36 kDa) from flax cells, designated LuPME5. This isoform corresponds to the Lupme5 cDNA isolated, at the same time, from flax hypocotyls, by using the RACE-PCR technique. Semi-quantitative PCR experiments showed that the Lupme5 transcript was highly expressed in the hypocotyl zones where elongation is being achieved. Thus, this enzyme may be involved in cell wall stiffening.

Amino Acid Sequence↗
PubMed2005

Silencing of the tobacco pollen pectin methylesterase NtPPME1 results in retarded in vivo pollen tube growth.

Sperm delivery in flowering plants requires extensive pollen tube growth through the female sporophytic tissues of the pistil. The apical cell wall emerges as a central player in the control of pollen tube growth, since it provides strength to withstand the internal turgor pressure, while imparting sufficient plasticity to allow cell wall extension through the incorporation of new membrane and wall material. Within this scenario, pectin methylesterases (PMEs; EC 3.1.1.11) emerge as crucial regulators in determining the mechanical properties of pectins, the major component of the apical pollen tube wall. We previously identified NtPPME1, a pollen specific PME from Nicotiana tabacum. Here we show that silencing of NtPPME1 results in a mild but significant decrease of in vivo pollen tube growth while the overall PME activity in pollen is not significantly affected. Although the precise mechanisms responsible for the observed phenotype are not known, it seems likely that the cell must maintain a closely regulated level of PME activity in order to maintain the equilibrium between strength and plasticity in the apical cell wall. A relatively minor disturbance of this equilibrium, as caused by NtPPME1 silencing, compromises pollen tube growth.

Carboxylic Ester Hydrolases↗
PubMed2003

Antisense transgenesis of tobacco with a flax pectin methylesterase affects pollen ornamentation.

Antisense transgenesis of tobacco (Nicotiana tabacum) with a partial flax (Linum usitatissimum L.) pectin methylesterase (Lupme3) cDNA sequence yielded plants with altered pollen content. Moreover, the characteristically sculptured cell wall surrounding the pollen grains was modified in transgenic tobacco plants: the wavy ornamentation was dramatically reduced, suggesting the involvement of the demethylation of pectin in the pollen cell wall-specific structure. Germination of pollen was decreased and the pollen tube surface aspect was also different in transgenic plants.

Carboxylic Ester Hydrolases↗