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[Localization of catalysis enzyme systems that degrade higher plants' cell wall polysaccharides. Pectinases (review)].

This paper reviews recent data on the locations and compositions of enzyme systems catalyzing the cleavage of cellulose, hemicelluloses, and pectin polysaccharides in higher plants. The physiological functions and physicochemical properties of certain enzymes degrading pectin polymers in higher plants, fungi, and bacteria are described.

Carbohydrate Sequence↗
PubMed2007

Enzyme-catalyzed change of antioxidants content and antioxidant activity of asparagus juice.

A pectolytic enzyme preparation from Aspergillus niger (pectinase AN) decreased most rutin content and antioxidant activity of asparagus juice. To investigate the mechanism of such loss, we analyzed several possible related enzyme activities in pectinase AN. We found that the activity of pectinase AN to oxidize guaiacol had no significant difference with or without the presence of H2O2; thus it was laccase activity, not peroxidase (PO) activity, that pectinase AN contained. We did not find any polyphenol oxidase (PPO) activity in pectinase AN. Laccase in pectinase AN could be the major cause of loss of rutin and antioxidant activity of asparagus juice. When most laccase activity of pectinase AN was inactivated after heating at 70 degrees C for 1.5 min and incubated with asparagus juice, the loss rate of rutin was only 9% of that treated with unheated pectinase AN, and the antioxidant activity was even increased. Rhamnosidase activity was detected in pectinase AN and can change rutin in asparagus juice to quercetin-3-glucoside, which has higher antioxidant activity than rutin. This may explain the increase of antioxidant activity of asparagus juice treated with heated pectinase AN that still contained some rhamnosidase activity. The discovery of our research is helpful to produce juice with high antioxidant activity and high health benefits in the juice industry.

Antioxidants↗
PubMed2002

Effect of macerate enzymes on the yield, quality, volatile compounds and rheological property of prickly pear juice.

Pectinase and cellulase enzymes were used to investigate efficacy for improving juice yield, stability and quality from prickly pear fruit. Pectinase improved the yield, stable color, color-assayed as release of anthocyanins or carotinoids and clarity of the juice. A significant increase in the effectiveness of pectinase was observed as the concentration was increased from 0.05 to 0.50% v/w. However, at concentration > 0.25% v/w they tended to impart a bitter flavor in the juice. Among three concentrations of pectinase and cellulase, pectinase at 0.50% v/w produced higher yield, a sediment-free clear juice and high-quality juice. The results indicated that depectinated clarified prickly pear juice behaves as a Newtonian fluid. It was found that the activation energy (Ea) for viscous flow was in the range of 5.02 x 10(3)-20.06 x 10(3) kJ/mol depending on the concentrations of pectinase and cellulase enzyme treatment of prickly pear juice, in contrast to 22.15 x 10(3) kJ/mol in untreated juice. Volatile compound concentrations of twelve compounds were not affected by pectinase and cellulase treatment. Overall the quality of prickly pear juice was better in pectinase-treated juice compared with untreated and cellulase-treated juice.

Beverages↗
PubMed1996

Regulation of pectinolysis in Erwinia chrysanthemi.

Erwinia chrysanthemi is an enterobacterium that causes various plant diseases. Its pathogenicity results from the secretion of pectinolytic enzymes responsible for the disorganization of the plant cell wall. The E. chrysanthemi strain 3937 produces two pectin methylesterases, at least seven pectate lyases, a polygalacturonase, and a pectin lyase. The extracellular degradation of the pectin leads to the formation of oligogalacturonides that are catabolized through an intracellular pathway. The pectinase genes are expressed from independent cistrons, and their transcription is favored by environmental conditions such as presence of pectin and plant extracts, stationary growth phase, low temperature, oxygen or iron limitation, and so on. Moreover, transcription of the pectin lyase gene responds to DNA-damaging agents. The differential expressions of individual pectinase genes presumably reflect their role during plant infection. The regulation of pel genes requires several regulatory systems, including the KdgR repressor, which mediates the induction of all the pectinolysis genes in the presence of pectin catabolites. KdgR also controls the genes necessary for pectinase secretion and other pectin-inducible genes not yet characterized. PecS, a cytoplasmic protein homologous to other transcriptional regulators, can bind in vitro to the regulatory regions of pectinase and cellulase genes. The PecT protein, a member of the LysR family of transcriptional regulators, represses the expression of some pectinase genes and also affects other metabolic pathways of the bacteria. Other proteins involved in global regulations, such as CRP or HNS, can bind to the regulatory regions of the pectinase genes and affect their transcription.

Carbohydrate Sequence↗
PubMed2000

Evaluation of enzymes produced from yeast.

Pichia pinus was found to be capable of growing on mango wastes, producing pectinase (pectin lyase, EC-4.2.2.10) and lactase (beta-galactosidase, EC-3.2.1.23) enzymes. The two enzymes were successively purified by precipitation with ammonium sulfate followed by chromatography on Sephadex G-120. The purification procedure provided 1,846 and 929 fold purification with 20.6 and 24% yield recovery of pectinase and lactase, respectively. the km value of pectinase was 0.33% for pectin at pH 4.5 and that for lactase was 0.166% for lactose at pH 7.0. The purified enzymes, pectinase and lactase are stable up to 50 degrees C for 60 and 45 min, respectively, with 20 and 35% loss of their activity. Gel filtration on Sephadex G-200 indicated that the molecular weights of the purified pectinase was 90 x 10(3) Dalton and of lactase 115 x 10(3) Dalton. On the basis of the evaluation tests done, the enzymes were considered to have a potential technological interest as treating mango pastes (residues left after mango juice preparation) with the two prepared enzymes resulted in an increase of the colour intensity, total carbohydrate content and juice yield. Treating milk with the purified lactase also showed an increase in the total carbohydrate and reducing sugar produced.

Chromatography, Gel↗
PubMed2006

Enzymatic hydrolysis of flavonoids and pectic oligosaccharides from bergamot (Citrus bergamia Risso) peel.

Pectinolytic and cellulolytic enzymes (Pectinase 62L, Pectinase 690L, and Cellulase CO13P) were used to evaluate the solubilization of carbohydrates and low molecular weight flavonoids from bergamot peel, a major byproduct of the essential oil industry. The enzymes were characterized for main-chain and side-chain polysaccharide hydrolyzing activities and also against pure samples of various flavonoids previously identified in bergamot peel to determine various glycosidase activities. The addition of Pectinase 62L or 690L alone, or the combination of Pectinase 62L and Cellulase CO13P, was capable of solubilizing between 70 and 80% of the bergamot peel, and up to 90% of the flavonoid glycosides present were cleaved to their aglycones. Cellulase CO13P alone solubilized 62% of the peel but had no deglycosylating effect on the flavonoid glycosides. Over a 24-h time course, a rapid release of cell wall carbohydrates was observed after treatment with Pectinase 62L, with a concurrent gradual hydrolysis of the flavonoid glycosides. Size-exclusion chromatography of the solubilized extract showed that after 24-h incubation, the majority of the solubilized carbohydrates were present as monosaccharides with a smaller proportion of oligosaccharides.

Cellulase↗
PubMed1997

Identification of a bacterial pectin acetyl esterase in Erwinia chrysanthemi 3937.

Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. The structural complexity of pectin requires the combined action of several pectinases for its efficient breakdown. Three types of pectinases have so far been identified in E. chrysanthemi: two pectin methyl esterases (PemA, PemB), a polygalacturonase (PehX), and eight pectate lyases (PelA, PelB, PelC, PelD, PelE, PelL, PelZ, PelX). We report in this paper the analysis of a novel enzyme, the pectin acetyl esterase encoded by the paeY gene. No bacterial form of pectin acetyl esterases has been described previously, while plant tissues and some pectinolytic fungi were found to produce similar enzymes. The paeY gene is present in a cluster of five pectinase-encoding genes, pelA-pelE-pelD-paeY-pemA. The paeY open reading frame is 1650 bases long and encodes a 551-residue precursor protein of 60704Da, including a 25-amino-acid signal peptide. PaeY shares one region of homology with a rhamnogalacturonan acetyl esterase of Aspergillus aculeatus. To characterize the enzyme, the paeY gene was overexpressed and its protein product was purified. PaeY releases acetate from sugar-beet pectin and from various synthetic substrates. Moreover, the enzyme was shown to act in synergy with other pectinases. The de-esterification rate by PaeY increased after previous demethylation of the pectins by PemA and after depolymerization of the pectin by pectate lyases. In addition, the degradation of sugar-beet pectin by pectate lyases is favoured after the removal of methyl and acetyl groups by PemA and PaeY, respectively. The paeY gene was first identified on the basis of its regulation, which shares several characteristics with that of other pectinases. Analysis of the paeY transcription, using gene fusions, revealed that it is induced by pectic catabolic products and is affected by growth phase, oxygen limitation and catabolite repression. Regulation of paeY expression appears to be dependent on the KdgR repressor, which controls all the steps of pectin catabolism, and on the catabolite regulatory protein (CRP), the global activator of sugar catabolism. The contiguous pelD, paeY and pemA genes are transcribed as an operon from a promoter proximal to pelD which allows the regulation by KdgR and CRP. However, transcription can be interrupted at the intra-operon Rho-independent terminator situated between pelD and paeY. The paeY mutant inoculated into Saintpaulia plants was less invasive than the wild-type E. chrysanthemi strain 3937, demonstrating the important role of PaeY in the soft-rot disease.

Acetylation↗