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At least 577 records · Page 32Linked to original sources
PubMed1994

[Effect of pectin additives from cotton on the physical development, nutrition and erythrocytes in infants].

The authors examined 156 babies on bottle feeding or breast and bottle feeding against control group of 60 babies whose diets were identical with the study group except additional intake of cotton-boll pectin. The latter was used for the first time as a biologically active ingredient of infant food (1 g per 100 ml of infant milk or food 3 times a day for 45-60 days). As a result of the pectin addition the infants of the study group had better nutritional status and physical development, their erythrocytic system was superior to that of the controls. It is stated that the addition of cotton-boll pectin to baby diet is beneficial for their health.

Bottle Feeding↗
PubMed1993

1H and 23Na NMR relaxation times study of pectin solutions and gels.

1H and 23Na longitudinal and transverse relaxation times have been measured to examine the concentration dependence of the dynamic behaviour of pectin solutions and gels. T1 and T2 relaxation times were measured in HDE pectin solutions and gels prepared with different cosolutes. A lowering of T1 and T2 values was observed in relation to a better efficiency of the intermolecular forces between polymer molecules and/or the formation of more extended junction zones. The T1/T2 ratio was also exploited indicating that even bulk water experiences anisotropic motions due to the gel formation. A correspondence of NMR results with previous reported data of rheological measurements of pectin gels prepared with the same cosolutes was found.

Chemical Phenomena↗
PubMed1976

[Structure and properties of complex gels of gelatin and pectin].

The authors studied the effects of aging time and composition on the thermomechanical properties of complex gels of gelatin and pectin which had been produced on the basis of complexes obtained at pH values below the isoelectric point of gelatin. With aging for up to 7 days, the elasticity of the gels decreases and the melting points are raised by 2--4degreesC. An increase in the relative content of pectin in the complex leads to a considerable rise of the melting point of the complex gel. The increase in heat stability of these gels is explained by the development of an ion lattice, which is due to the interaction of the oppositely charged groups of the pectin and the gelatin. Furthermore, hydrophobic interactions between the non-polar groups of the components might be involved.

Gelatin↗
PubMed1997

[A 13-week subacute oral toxicity study of pectin digests in rats].

A 13-week subacute oral toxicity study of pectin digests was performed in both sexes of F344 rats. Water containing 0, 0.15, 0.5, 1.5 or 5% pectin digests was fed to 10 males and 10 females per group to detect its toxicity. No animals died during the administration period. Body weight gain was suppressed in male of the 5% group compared with the 0% group. Serum biochemistry analysis revealed a significant increase in BUN in male group treated with 5% and increases in CRN in male group treated with 1.5% or more. The weight of liver was significantly increased in female groups treated with 1.5% or more. Histopathologically, no treatment-related damage was observed in any dosed groups. Based on these results, the NOEL of pectin digests for both sexes in F344 rats was considered to be 0.5% in drinking water (male 545, female 657 mg/kg/day).

Administration, Oral↗
PubMed1998

Characterization of enzymatic pectin digests by matrix-assisted laser desorption/ionization mass spectrometry.

The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the characterization of partially methyl-esterified enzymatic pectin digests is described. The sensitivities of several matrices, positive and negative ion modes and desalting techniques for these acidic oligosaccharides were compared. The most favorable results were obtained with a thin-layer preparation of a mixture of 2,4,6-trihydroxyacetophenone and nitrocellulose in the negative ion mode. Results are presented demonstrating the sensitive characterization of separated and unseparated high-ester pectin digests obtained after complete digestion using Aspergillus niger pectin lyase and the analysis of digests after chemical modification. In the case of unseparated digests, the analysis of methylation patterns is demonstrated. Oligomers with a degree of polymerization up to 40 were detected after enrichment of large oligomers by propan-2-ol precipitation.

1-Propanol↗
PubMed1993

Isolation and characterization of pectin methylesterase from papaya.

Pectin methylesterase (PME) (EC 3.1.1.11) has been purified to apparent homogeneity from ripe papaya fruits. The purification protocol consisted of ammonium sulphate precipitation (60-80%) and cation exchange chromatography in CM Sepharose CL-6B and Mono S. Papaya PME consists of two components (PME 1 and PME 2), which have been shown to be isoenzymes by Ferguson plot analysis. The molecular weight of the enzyme is 27,000 while its isoelectric point is greater than pH 9.0. The N-terminal sequences of PME 1 and PME 2 are SVVTPNAVVADDGVFXFKTG. Both PME 1 and PME 2 showed optimum activities at pH 8.0 and 35 degrees C. The average Kms of PME 1 and PME 2 are 0.0071 and 0.0166 g/liter pectin respectively, while the corresponding average Vmaxs are 741 and 800 mumol methanol/min/mg protein, respectively. Papaya pectin methylesterase is activated by cations, but the effect is more pronounced for divalent than monovalent cations. Inhibition studies showed that sucrose is a noncompetitive inhibitor while p-chloromercuribenzoic acid has no significant effect on its activity.

Amino Acid Sequence↗
PubMed2002

Gelation of aqueous pectin solutions: a dynamic light scattering study.

We report the dynamic light scattering study of the gelation of aqueous solutions of the biopolymer, pectin, induced by the addition of calcium chloride. The time correlation function data are analyzed under the framework of the coupling model. As the solution enters the semidilute regime where gelation sets in, the relaxation process shows a stretched exponential behavior. The stretching exponent decreases and the characteristic time of the stretched exponential diverges as the system evolves to a gel. Aqueous pectin solutions in the presence of 0.1 M NaCl show similar behavior. Thus, the molecular relaxation modes of pectin solutions can be well described by the coupling model.

Journal Article↗
PubMed1997

Electrophysiological evidence of synaptic interactions within chemosensory sensilla of scorpion pectines.

The pectines of scorpions are ventral bilateral appendages supporting 10(4)-10(5) chemosensory sensilla called pegs. Each peg contains 10-18 sensory neurons, some of which show ultrastructural evidence of axo-axonic synapses with other sensory neurons in the same sensillum. In extracellular recordings from single-peg sensilla, individual sensory units can be distinguished by impulse waveform and firing frequency. Cross-correlation analysis of impulse activity showed that at least two of these units, types 'A1' and 'A2', are inhibited during the 100-ms period immediately following activity of a third unit, type 'B'. This interaction between sensory units in a single sensillum also occurs in surgically isolated pectines, indicating that it does not involve efferent feedback from the central nervous system. Other sensillar neurons appear to have excitatory interactions. Thus, in scorpion pectine, chemosensory information undergoes some form of processing within individual sensilla prior to its relay to the CNS, making this an unusually accessible preparation for study of first-order chemosensory processing events.

Animals↗
PubMed1999

A novel function for a ubiquitous plant enzyme pectin methylesterase: the host-cell receptor for the tobacco mosaic virus movement protein.

Plant virus-encoded movement proteins promote viral spread between plant cells via plasmodesmata. The movement is assumed to require a plasmodesmata targeting signal to interact with still unidentified host factors presumably located on plasmodesmata and cell walls. The present work indicates that a ubiquitous cell wall-associated plant enzyme pectin methylesterase of Nicotiana tabacum L. specifically binds to the movement protein encoded by tobacco mosaic virus. We also show that pectin methylesterase is an RNA binding protein. These data suggest that pectin methylesterase is a host cell receptor involved in cell-to-cell movement of tobacco mosaic virus.

Base Sequence↗
PubMed2001

Purification of several pectin methyltransferases from cell suspension cultures of flax (Linum usitatissimum L.).

Three pectin methyltransferases (PMT5, PMT7, PMT18; EC 2.1.1.6.x) were solubilized from the endo-membrane complex of flax cells, with 0.05% Triton X-100. After a 3 step-chromatography procedure, PMT7 and PMT5 were purified to apparent homogeneity. PMT5 and PMT7 differed regarding their optimum pH (5 or 7), the methyl acceptor (low or highly methylesterified pectin), their focusing pH range (6-7 or 8-9) and relative molecular mass (40 +/- 5 or 110 +/- 10 kDa). SDS-PAGE of PMT5 and PMT7 did not reveal bands at 40 or 110 kDa but only a silver stained band of about 18 kDa. Two independent methods (photo labelling and enzymatic activity) showed that this silverstained band corresponded to a methyltransferase with affinity for pectins. This polypeptide was of the same size as the enzyme designed PMT18 (18 +/- 3 kDa; pl 4-4.5) recovered during size exclusion chromatography of either PMT7 or PMT5, suggesting that PMT18 bears the catalytic site of PMT5 and PMT7.

Electrophoresis, Polyacrylamide Gel↗
PubMed1998

A maize pectin methylesterase-like gene, ZmC5, specifically expressed in pollen.

Pectin methylesterase (PME) is responsible for the demethylation of pectin prior to pectin's degradation by the combined activities of polygalacturonase and pectate lyase. We have differentially screened a maize pollen cDNA library to detect cDNA clones whose genes are specifically expressed in pollen. One group of clones resulting from this screen showed similarity (between 18% and 41% identity) with plant and fungal PMEs. The full-length clone from this group, ZmC5, identifies a small gene family (at least 2 members) when used as a probe on genomic Southern blots. Northern analysis reveals that the ZmC5 transcript is expressed specifically in late pollen development. This tissue-specific gene expression programme is further confirmed in transgenic tobacco plants harbouring ZmC5 promoter/GUS chimeric gene constructs.

Base Sequence↗
PubMed2001

Overexpression of a heterologous sam gene encoding S-adenosylmethionine synthetase in flax (Linum usitatissimum) cells: Consequences on methylation of lignin precursors and pectins.

The Arabidopsis thaliana sam1 gene encoding S-adenosylmethionine synthetase (EC 2.5.1.6) was transferred to flax (Linum usitatissimum) cells via Agrobacterium tumefaciens. This enzyme catalyses the conversion of methionine to S-adenosylmethionine (SAM), the major methyl group donor in living cells. The aim of this work was to study the consequences of an increased SAM-synthetase (SAM-S) activity in transgenic cell lines on both the production of mono- and dimethoxylated lignin monomers and the degree of methylesterification of pectins. Hypocotyls were cocultivated with Agrobacterium tumefaciens strain GV3101 (pGV2260) harbouring the pO35SSAM binary vector carrying the sam1 gene under the control of the 35S promoter and the nptII gene for selection of putative transformed cells. Most of the transgenic cell lines exhibited a significant (up to 3.2-fold) increase in SAM-S activity compared to the controls. The results showed that for the cell lines analysed this transformation had no effect on caffeic acid O-methyltransferase (COMT, EC 2.1.1.68) in vitro activity, degree of methoxylation of lignin precursors or lignin deposition, pectin methyltransferase (PMT, EC 2.1.1) in vitro activity, but led to an increase of pectin methylesterification in friable and fast-growing transgenic cell lines.

Journal Article↗
PubMed2005

A cold-active pectin lyase from the psychrophilic and basidiomycetous yeast Cystofilobasidium capitatum strain PPY-1.

In the present study we purified a cold-active PNL (pectin lyase) from the extracellular fraction of the PPY (pectinolytic and psychrophilic yeast) Cystofilobasidium capitatum strain PPY-1. The purified PNL has a molecular mass of approx. 42 kDa, and its N-terminal amino acid sequence is ATGVTGSAYGFATGTTGGGSATPAY, which exhibits 72% identity with that of PNL F from Aspergillus niger. The purified PNL exhibited high activity at 10 degrees C, although its optimum temperature was 40 degrees C. Moreover, Km and Vmax for pectin as a substrate were found to have values 36.6 mg/ml and 3000 units/mg respectively. These findings may indicate that this enzyme from strain PPY-1 is a cold-active PNL that is able to degrade pectin compounds at low temperature.

Amino Acid Sequence↗
PubMed1994

Atrial natriuretic peptide is produced less in the intercaval sinus than in the pectinated right atrium.

To explain the lower atrial natriuretic peptide concentrations after total cavopulmonary connection than after the Fontan procedure, a prospective study was carried out in seven rats to count the specific granules of atrial natriuretic peptide by electronmicroscope. After fasting from water for 12 days, the quantity of specific granules in the right atrial appendage (pectinated part), intercaval sinus (smooth part), and superior vena cava were counted. The number of specific granules present in the pectinated part of right atrium was 97 +/- 19 in 20 cells, while in the intercaval sinus it was 23 +/- 19 (mean +/- SD). The difference was significant statistically (p < 0.0001). No granule was present in the superior vena cava. We conclude that the granularity of atrial natriuretic peptide is less in the intercaval sinus than the pectinated part of the right atrium.

Animals↗
PubMed2001

Perfusion chromatography separation of the tomato fruit-specific pectin methylesterase from a semipurified commercial enzyme preparation.

A rapid and simple method was developed, using perfusion chromatography media, to separate the fruit-specific pectin methylesterase (PME) isoform from the depolymerizing enzyme polygalacturonase (PG) and other contaminating pectinases present in a commercial tomato enzyme preparation. Pectinase activities were adsorbed onto a Poros HS (a strong cation exchanger) column in 20 M HEPES buffer at pH 7.5. The fruit-specific PME was eluted from the column with 80 mM NaCl, followed by a step to 300 mM NaCl to elute PG activity. Rechromatography of the PME activity peak with a linear gradient further resolved two PME isoenzymes and removed residual traces of PG activity. The PG activity peak was further treated with lectin affinity chromatography to provide purified PG enzyme, which was separated from a salt-dependent PME (tentatively identified as a "ubiquitous-type" isoform), and a pectin acetylesterase. The later enzyme has not been reported previously in tomato. This method provides monocomponent enzymes that will be useful for studying enzyme mechanisms and for modifying pectin structure and functional properties.

Amino Acid Sequence↗
PubMed2002

An Arabidopsis thaliana pectin acetylesterase gene is upregulated in nematode feeding sites induced by root-knot and cyst nematodes.

By using differential display, gene expression was investigated in Arabidopsis thaliana roots shortly after nematode infection, and a putative pectin acetylesterase (PAE) homolog (DiDi 9C-12) was found to be upregulated. PAEs catalyze the deacetylation of pectin, a major compound of primary cell walls. mRNA in situ hybridization experiments showed that the expression of DiDi 9C-12 was enhanced very early after infection in initiating giant-cells and in cells surrounding the nematodes. Later on, the level of DiDi 9C-12 mRNA was lower in giant-cells and transcripts were mainly found in parenchyma, endodermis, and pericycle cells of the root gall. Twenty days after infection, DiDi 9C-12 transcripts could no longer be detected. DiDi 9C-12 transcripts were also found in young syncytia and in the cells surrounding the expanding syncytium. Our results suggest that plant parasitic nematodes can modulate the rapid growth of the feeding cells and the expansion of the root gall by triggering the expression of DiDi 9C-12. PAEs, which probably act together with a range of other pectin-degrading enzymes, could be involved in softening and loosening the primary cell wall in nematode-infected plant roots.

Amino Acid Sequence↗
PubMed1994

Molecular cloning and expression in Escherichia coli of genes encoding pectate lyase and pectin methylesterase activities from Bacteroides thetaiotaomicron.

Bacteroides thetaiotaomicron strain 217 can use pectins as a sole carbon source. Preliminary characterization of the pectinolytic enzymes revealed three complementary activities in this strain: a pectin methylesterase (PME), a pectate lyase (PL) and a polygalacturonase (PG), which were all inducible by pectin or polygalacturonate. Use of the lambdoid phage replacement vector lambda EMBL3 allowed a 13.2 kb insert mediating both PL and PME activities to be isolated. Subcloning of two EcoRI fragments in pBR325 led to the separate isolation of the pel and pme genes. They were expressed constitutively in Escherichia coli HB101, as proved by the activities observed even in mineral medium supplemented only with glucose. In addition, the pme gene was expressed in both orientations. These results suggest that each gene represents an individual transcriptional unit. Several properties of the cloned PL were different from those of the original strain: it was mainly associated to the outer membrane, its optimum pH was higher, and its stability at 50 degrees C was lost but partially preserved by CaCl2. In addition, the apparent specific PL activity in the E. coli membrane fraction was about 30-fold higher. On the other hand, most of the properties of the cloned PME were similar to those of the original. Despite an enhanced thermostability, the apparent specific activity of the cloned PME was about 6-fold lower, and was independent of the insert orientation.

Bacteroides↗
PubMed1989

Pectin Lyase Production by a Penicillium italicum Strain.

Growth and concomitant production of an extracellular pectin lyase (PL) [poly(methoxylgalactosiduronate) endolyase; EC 4.2.2.10] were investigated in a group of 16 fungi grown in liquid medium containing pectin as a supplementary carbon source. Culture filtrates of both Penicillium italicum (CECT 2294) and P. expansum (CECT 2275) showed the highest PL activity and contained polygalacturonase but not pectinesterase activity. The effect of the inoculum size, the carbon source (sucrose and glucose syrup), and the presence of pectin on the production of PL by P. italicum was studied. The presence of 2.6 mM glycerophosphate in the culture medium enhanced the appearance of PL but was not inhibitory for the in vitro activity. However, glycerol inhibited the enzyme nearly 50% at such a concentration.

Journal Article↗