Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PECTINS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2003

Thermodynamic parameters of beta-lactoglobulin-pectin complexes assessed by isothermal titration calorimetry.

Isothermal titration calorimetry (ITC) was used to determine the binding constant, stoichiometry, enthalpy, and entropy of beta-lactoglobulin/low- and high-methoxyl pectin (beta-lg-LM- and HM-pectin) complexes at 22 degrees C and at pH 4. The binding isotherms revealed the formation of soluble intrapolymer complexes (C1) further followed by their aggregation in interpolymer complexes (C2). The interaction between beta-lg and LM- or HM-pectin in C1 and C2 occurred spontaneously with a Gibbs free energy around -10 kcal/mol. The C1 were enthalpically driven, whereas enthalpic and entropic factors were involved in the C2 formation. Because ITC did not allow the dissociation of different enthalpic contributions, the values measured as pectin and beta-lg interacted could partially be attributed to conformational changes. The C1 had a binding stoichiometry of 8.3 and 6.1 beta-lg molecules complexed per LM- or HM-pectin molecule, respectively. The C2 had about 16.5 and 15.1 beta-lg molecules complexed per LM- and HM-pectin, respectively.

Calorimetry↗
PubMed2006

Characterization of the temperature activation of pectin methylesterase in green beans and tomatoes.

Low-temperature blanching of vegetables activates the enzyme pectin methylesterase (PME), which demethylates cell wall pectins and improves tissue firmness. This temperature activation of PME has been investigated by measuring the formation of methanol in intact tissue of green beans and tomatoes. Rates of methanol formation at temperatures of 35-65 degrees C were obtained by measuring the release of methanol from thin slices of tomato pericarp or green bean pod material. Activation energies of 112 and 97 kJ mol(-1) were calculated for PME activity in green beans and tomatoes, respectively. These activation energies indicate that the rate of pectin demethylation at 65 degrees C will be nearly 100 times that at 25 degrees C. PME activity was also determined titrimetrically using a solubilized form of the enzyme and purified pectin at temperatures from 30 to 60 degrees C. Under these conditions, much lower activation energies of 37 and 35 kJ mol(-1) were obtained for green beans and tomatoes, respectively. Methanol accumulation during heating of whole intact green beans was also determined and yielded an activation energy similar to that obtained with sliced beans. Whole green beans held at room temperature did not accumulate any methanol, but sliced or homogenized beans did. If whole beans were first heated to 45 degrees C and then cooled, methanol accumulation was observed at room temperature. These results indicate that two factors contribute to the observed high rate of pectin de-esterification during low-temperature blanching: (1) An irreversible change, causing PME to become active, occurs by heating to > or = 45 degrees C. (2) The high activation energy for pectin de-esterification means that the rate of de-esterification increases substantially with increasing temperature.

Calcium↗
PubMed1993

In vitro evaluation of calcium pectinate: a potential colon-specific drug delivery carrier.

Calcium pectinate (CaP)--the insoluble salt of pectin--can potentially be used as a colon-specific drug delivery system. The use of CaP as a carrier was based on the assumption that, like pectin, it can be decomposed by specific pectinolytic enzymes in the colon but that it retains its integrity in the physiological environment of the small bowel. The biodegradation of the carrier was characterized by monitoring the percent cumulative release of the insoluble drug indomethacin, incorporated into pectin or CaP matrices. Compressed tablets of pectin and indomethacin were analyzed for degradation in the presence of Pectinex 3XL, a typical pectinolytic enzyme mixture, and in the presence of the human colonic bacterium Bacteroides ovatus. The degradation of CaP-indomethacin tablets was assessed in the presence of Pectinex 3XL and in rat cecal contents. The release of indomethacin was significantly increased (end-time percentage cumulative release vs control) in the presence of Pectinex 3XL (89 +/- 20 vs 16 +/- 2 for CaP tablets), Bacteroides ovatus (12 and 22 vs 5.2 for pectin tablets), and rat cecal contents (61 +/- 16 vs 4.9 +/- 1.1 for CaP tablets). The weight loss of tablet mass was significantly higher (end-time dry weight vs control) in the presence of Pectinex 3XL (0 vs 75 +/- 6% of initial weight for CaP tablets). These findings indicate the potential of CaP, compressed into tablets with insoluble drug, to serve as a specific drug delivery system to the colon.

Animals↗
PubMed1989

Bile acid conjugation and hepatic taurine concentration in rats fed on pectin.

A relationship between bile acid conjugation and hepatic taurine concentration was investigated in rats fed on citrus pectin. When rats were fed on the diets containing varying amounts of pectin (10, 30, 60 and 100 g/kg dietary levels), biliary excretion of bile acids increased as the dietary levels of pectin increased. The increase was entirely due to the glycine-conjugated bile acids. The biliary excretion of taurine-conjugated bile acid was somewhat decreased as the dietary level of the fibre increased. Consequently, most of the bile acids were conjugated with glycine in rats fed on the diet containing 100 g pectin/kg. On the other hand, dietary cellulose (60 and 100 g/kg) did not affect the biliary bile acid excretions. The major proportion of bile acids in rats receiving a fibre-free diet and the diets containing cellulose were conjugated with taurine. Hepatic taurine concentrations decreased as the dietary levels of pectin, but not of cellulose, increased. Although dietary pectin (100 g/kg) also slightly decreased the taurine concentration in the kidney, those concentrations in other non-hepatic tissues examined (heart, brain and serum) were unaffected by the dietary fibre. Supplementation of the diet containing 100 g pectin/kg with methionine (10 g/kg) and taurine (10 and 50 g/kg) strikingly increased hepatic taurine concentrations. In this situation, the conjugation of bile acid with glycine was almost abolished and taurine conjugates became abundant in the bile of these animals. It is suggested that dietary pectin mediated an increase in the biliary bile acid excretion which may have depleted the hepatic pool of taurine available for bile acid conjugation and, thus, increased glycine conjugation of bile acids.

Animals↗
PubMed1997

Broiler chicken body weights, feed intakes, plasma lipid and small-intestinal bile acid concentrations in response to feeding of chitosan and pectin.

One-day-old broiler chickens were fed on a control diet based on maize and maize starch or diets containing 30 g/kg of 89% deacetylated chitin (chitosan) or low-methoxyl (34% degree of esterification) pectin. Feeding of the chitosan diet to chickens significantly reduced body weights and feed intakes compared with animals fed on control or pectin diets on days 5 and 11 of the experiment. On day 12, significant reductions in total plasma cholesterol and HDL-cholesterol concentrations were observed among birds fed on the chitosan but not the pectin diet in relation to control-fed animals. A concomitant increase in the plasma HDL-cholesterol:total cholesterol ratio was observed among chitosan-fed chickens. The generally reduced concentrations of primary and total bile acids in the duodenum of birds fed on the fibre-containing diets on day 13 may have been an indication of a delay in the production and/or secretion of bile. Viscosity of the three broiler-chicken diets was measured after suspension in water, acidification and finally neutralization of the suspensions, in an attempt to simulate the effect of changes in pH and dilution of diets occurring in the gizzard and small intestine of chickens. Viscosity of the chitosan diet was significantly elevated after acidification and significantly reduced at neutralization in comparison with the control and pectin-containing diets suggesting that the hypolipidaemic influence of chitosan observed in the present study may be due to interruption of enterohepatic bile acid circulation rather than increased viscosity in the small intestine of chickens. The low viscosity of the pectin diet in vitro together with the absence of a hypocholesterolaemic effect of this diet when fed in vivo precludes any conclusion regarding the hypocholesterolaemic mechanism of pectin observed in earlier studies.

Animals↗
PubMedDate not supplied

Bovine serum albumin-loaded pectinate beads as colonic peptide delivery system: preparation and in vitro characterization.

Objective of this study was to prepare a drug delivery system for therapeutic peptides that are degraded in the upper part of the gastrointestinal tract due to degradation activity of the enzymes. Delivering peptide to the colon in which enzymatic activity is low is next hope for absorption of these agents. Pectin, a naturally occurring water soluble polysaccharide, as a matrix for peptide delivery was studied. Degradation of pectin by the colonic enzymes makes it suitable for colon-specific delivery of drugs. Bovine serum albumin (BSA) was used as a model peptide. Calcium pectinate beads were prepared by extruding BSA-loaded pectin solution to an agitating calcium chloride solution, and gelled spheres were formed instantaneously by an ionotropic gelation reaction. The effect of several factors such as concentration of pectin, concentration of calcium chloride, and total drug loading on the pattern of drug release in the dissolution medium was studied. Prepared beads showed good resistance in the release medium. The entrapment efficiency of the beads was high (between 63% and 99%). Entrapment efficiency of BSA was reversely dependent to the amount of the drug loaded in the beads. The amount of BSA loaded on the beads affects pattern of drug release. The concentration of the pectin showed the highest impact on the rate of drug release. Presence of the pectiolytic enzymes facilitated the drug release from the beads.

Calcium Chloride↗
PubMed2003

Transdermal delivery of chloroquine by amidated pectin hydrogel matrix patch in the rat.

The aim of the present study was to investigate the suitability of amidated pectin matrix patch for transdermal chloroquine delivery in an effort to mask the bitter taste when orally administered. Chloroquine has easily measurable outputs that are linked to increased renal Na+ excretion. We thus monitored urinary Na+ output in separate groups intravenously administered chloroquine or topically applied pectin hydrogel chloroquine matrix patch. Male groups of anesthetized Sprague-Dawley rats were placed on a continuous jugular infusion of 0.077 M NaCl at 150 microL min(-1). After 3 h equilibration period, consecutive 20 min urine collections were made over the subsequent 4 h of 1 h control, 1 h 20 min treatment, and 1 h 40 min recovery periods for measurements of urine flow and Na+ and K+ excretion rates. The effects of intravenous chloroquine infusion or topical application of pectin hydrogel chloroquine matrix patch were examined in rats in which the drug was added to the infusate or patch applied onto the shaved area during the 1 h 20 min treatment period. The animals were switched back to the infusate alone for the final 1 h 40 min recovery period. Vehicle infused animals acted as controls. Trunk blood was collected after the treatment period from parallel groups for chloroquine measurements. The plasma chloroquine concentrations following iv chloroquine or application of pectin chloroquine hydrogel matrix patch were 9.3 +/- 0.8 mg L(-1) and 7.3 +/- 1.1 mg L(-1) respectively (n = 7 in both groups). Chloroquine infusion and pectin chloroquine patch significantly (p < 0.01) increased Na+ excretion to peak values of 14.1 +/- 0.9 micromol min(-1). and 20.35 +/- 1.0 micromol min(-1), respectively by comparison with controls (9.1 +/- 0.9 micromol min(-1)), at the corresponding period. The results suggest that the pectin chloroquine patch matrix preparation has potential applications for transdermal delivery of chloroquine and perhaps in the management of malaria.

Administration, Cutaneous↗
PubMed2004

Asian pear pectin administration during presensitization inhibits allergic response to ovalbumin in BALB/c mice.

OBJECTIVE: A type of respiratory disorder resembling some aspects of human allergic asthma can be induced in mice using ovalbumin. The factors that influence the etiology of asthma are poorly understood even though cytokines are known to play a pivotal role. The purpose of this study was to test the hypothesis whether an administration of Asian pear pectin during presensitization could suppress allergic response to ovalbumin in BALB/c mice. DESIGN: High-dose (100 microg) of pectin-sol was used and values were compared to those from the control. Ovalbumin and aluminum hydroxide were utilized for sensitization while ovalbumin aerosol was used for provocation 2 weeks later. The bronchoalveolar lavage (BAL) and assessment of tracheal smooth muscle responsiveness to electrical field stimulation or acetylcholine were performed 1 day after ovalbumin provocation. Two main cytokines of interferon (IFN)-gamma and interleukin (IL)-5, and serum immunoglobulin E (IgE) were assayed. SETTINGS: Laboratory of the Chosun University Medical School SUBJECT: Male BALB/c mice RESULTS: Antigen dose of 5 microg for sensitization generated TH1 type cytokines in the lungs with a high level of IFN-gamma and a low level of IL-5. In contrast, TH2 type cytokines were produced in splenocytes including a high level of IL-5 and a low level of IFN-gamma. Asian pear pectin-sol administration during presensitization significantly inhibited (p < 0.05) sensitivity of airway smooth muscle to electrical field stimulation and acetylcholine. Further, IFN-gamma production significantly decreased (p < 0.05) in BAL fluids while it significantly increased (p < 0.05) in splenic cells. On the other hand, IL-5 production significantly increased (p < 0.05) in BAL fluids while it was a significant decrease (p < 0.05) in splenic cells. For the histopathologic changes in the lung, pear pectin-sol recovered ovalbumin (OVA)-induced abnormal signs to an almost normal state. As a correlate, IgE production significantly decreased (p < 0.05) in pectin-sol-treated animals compared to the control. CONCLUSIONS: It is possible from these data that BALB/c mice have different susceptibilities to different doses of OVA regulated by pulmonary TH1 and TH2 type cytokines, independent of splenic TH1 and TH2 type cytokines production. These results also indicate that administration of Asian pear pectin-sol in presensitized mice suppresses allergic asthmatic reaction.

Allergens↗
PubMed1982

Effect of pectin structure on protein utilization by growing rats.

The effect of pectins' molecular weight (MW) and degree of esterification (DE) on apparent digestibility (D), net protein utilization (NPU) and biological value (BV) of casein were tested. The pectins prepared differed in MW and DE respectively as follows: P-1 (180,000, 73%); P-2 (300,000, 28%); P-3 (60,000, 74%) and P-4 (75,000, 40%) and were fed as 10% of a purified diet containing 10% casein to growing male rats for 10 days. All preparations decreased D, with P-2 and P-4 showing milder effects than P-1 or P-3. Increased NPU was observed with pectins of low NW and/or DE, being significant only with P-4. Diets containing P-2, P-3 or P-4 had higher BV for casein than the pectin-free diet. Feeding these pectins in a protein-free diet did not cause a significant change in the rats' body N content. Thus, the increase in the BV of casein was attributed to improvements in the pattern of amino acids absorbed by rats fed pectins with low MW and/or low DE.

Animals↗
PubMed1984

The effect of protein levels on the response of weanling rats to dietary pectin.

We have previously proposed that the inhibiting effects of pectin on feed consumption and growth might be due in part to the reduction it causes in protein digestibility. The present work was intended to test this hypothesis by feeding higher levels of protein in order to compensate for the lower digestibility. We fed diets containing 10, 20 and 30% casein (initial levels) and 0, 4.8, 16.7 and 28.6% pectin (by diet dilution). Despite the higher casein levels, pectin strongly inhibited the animals' feed intake, growth, protein efficiency ratio (PER), net protein ratio (NPR) and net protein utilization (NPU) as well as protein and energy digestibilities. Apart from determining the base (zero pectin) level of the various parameters measured, the dietary casein level in itself did not influence the effect of pectin on feed intake, digestible energy intake, protein digestibility, body weight growth or parameters of protein utilization such as PER, NPR and NPU. We thus cannot conclude that these effects of pectin were to any major extent secondary to the reduction in protein digestibility observed in these animals.

Animals↗
PubMed1986

Effects of oral and intracecal pectin administration on blood lipids in minipigs.

The effects on blood lipids of oral and intracecal pectin administration for 4 wk were examined in six male adult hypercholesterolemic minipigs (total serum cholesterol = 8.4 mmol/L. The pigs were fitted with a cecal cannula and were assigned to three groups of two pigs each; the groups underwent an experiment in 3 X 3 Latin square design. The control period was designated as that during which water was infused into the cecum. Total serum cholesterol concentration was about 50% lower after feeding 75 g pectin per day than during the control period. The intracecal infusion of the same amount of pectin had no effect on total serum cholesterol concentration compared to the control period. The cholesterol level in the low density lipoproteins (LDL), in the very low density lipoproteins (VLDL) and in the high density lipoproteins (HDL) was lower after feeding pectin than in the control period. The HDL cholesterol, but not LDL or VLDL cholesterol, was at a lower level after intracecal infusion of pectin than during the control period. Thus, the study clearly demonstrates that the passage of pectin through the small intestine is necessary for its hypocholesterolemic action.

Administration, Oral↗
PubMed1989

Effects of dietary fish oil or pectin on blood pressure and lipid metabolism in the DOCA-salt hypertensive rat.

This study investigated the effects of diets containing fish oil or pectin on blood pressure and lipid metabolism in the deoxycorticosterone acetate (DOCA)-salt hypertensive rat. Three groups (8 rats/group) of unilaterally nephrectomized rats were fed for 21 d one of three purified diets: a) 8% fish oil + 2% safflower oil + 5% alpha cellulose (fish oil diet), b) 10% safflower oil + 5% pectin (pectin diet), or c) 10% safflower oil + 5% alpha cellulose (control diet). Each of the diets contained 6% NaCl and all rats received DOCA (30 mg/kg body wt, subcutaneously) twice weekly. Systolic blood pressure of rats fed fish oil was significantly lower (P less than 0.05) than that of rats fed the control diet; there was no significant difference between the pectin and control groups. Plasma renin activity and net sodium and potassium balances were similar among the three groups. Plasma total cholesterol, LDL cholesterol and HDL cholesterol were significantly lower (P less than 0.05) in the group fed the fish oil diet than in the group fed the control diet. Total, LDL and HDL cholesterol did not differ between rats fed the pectin and rats fed the control diet. Plasma triglyceride concentration did not differ among the three groups. Thus, dietary fish oil attenuated the development of DOCA-salt hypertension, unrelated to alterations of net sodium balance. Fish oil feeding also lowered total, LDL and HDL cholesterol, but did not alter the HDL/LDL ratio. In contrast, dietary pectin exerted no effect on blood pressure or lipid metabolism.

Animals↗
PubMed1994

Dietary pectin's effect on ileal and fecal amino acid digestibility and exocrine pancreatic secretions in growing pigs.

The effect of dietary pectin on apparent ileal and fecal digestibilities of protein and amino acids and on pancreatic secretions was studied in two experiments with growing pigs (initial weight 70 kg). Four barrows were fitted with simple T-cannulas for collection of ileal digesta; another four barrows were fitted with permanent re-entrant cannulas for collection, sampling and subsequent return of pancreatic juice. Dietary pectin included at a level of 7.5 g/100 g in a cornstarch-based diet significantly depressed apparent ileal and fecal protein and amino acid digestibilities. This depression in the small intestine could be attributed to both an increase in endogenous protein secretions and a decrease in the efficiency of digestion. In the large intestine, pectin was used by intestinal microbes as the principal energy source to catabolize nitrogenous compounds and to stimulate bacterial nitrogen assimilation, thus altering the amino acid profile of protein voided in feces. The inclusion of pectin did not affect the flow of pancreatic juice or the total secretion of protein, lipase, trypsin and chymotrypsin. However, there was a significantly lower secretion of alpha-amylase, which was a direct result of the replacement of starch by pectin. The results demonstrate that pectin may have a detrimental effect on the processes of protein digestion and absorption but does not affect the secretion of pancreatic proteolytic enzymes in pigs.

Amino Acids↗
PubMed1998

Dietary guar gum and pectin stimulate intestinal microbial polyamine synthesis in rats.

The effects of two highly fermentable dietary fibers (guar gum and pectin) on the type and concentrations of cecal polyamines as affected by the intestinal microflora were studied in groups of germ-free (n = 10/group) and conventional rats (n = 6/group). Both germ-free and conventional rats were randomly assigned to one of three treatments as follows: 1) fiber-free control diet, 2) control diet + 10% guar gum and 3) control diet + 10% pectin. In germ-free rats, guar gum and pectin had no effect on cecal polyamine concentrations. Putrescine was confirmed to be the major endogenous polyamine within the gut lumen. In cecal contents of conventional rats, both guar gum and pectin led to the appearance of cadaverine and to elevated putrescine concentrations in comparison with the fiber-free control diet (1.35 +/- 0.15 and 2.27 +/- 0.32, respectively, vs. 0.20 +/- 0.03 micromol/g dry weight, P < 0.05). The cecal cadaverine concentration was higher in pectin- than in guar-fed rats (8.20 +/- 0.89 vs. 1.92 +/- 0.27 micromol/g dry weight, P < 0.05). Counts of total bacteria, bacteroides, fusobacteria and enterobacteria were higher (P < 0.05) in rats fed guar gum and pectin. Bifidobacteria were found exclusively in guar-fed rats. In vitro studies on selected species representing the numerically dominant population groups of the human gut flora (bacteroides, fusobacteria, anaerobic cocci and bifidobacteria) were examined for their ability to synthesize intracellular polyamines. These experiments demonstrated the ability of bacteroides, fusobacteria and anaerobic cocci to synthesize high amounts of putrescine and spermidine. Calculations based on these results suggest that the intestinal microflora are a major source of polyamines in the contents of the large intestine.

Animals↗
PubMed2005

Wall-associated kinase WAK1 interacts with cell wall pectins in a calcium-induced conformation.

Wall-associated kinase 1 (WAK1) is a transmembrane protein containing a cytoplasmic Ser/Thr kinase domain and an extracellular domain in contact with the pectin fraction of the plant cell walls. In order to characterize further the interaction of WAK1 with pectin, a 564 bp DNA sequence corresponding to amino acids 67-254 of the extracellular domain of WAK1 from Arabidopsis thaliana was cloned and expressed as a soluble recombinant peptide in yeast. Using enzyme-linked immunosorbent assays (ELISA), we show that peptide WAK(67-254) binds to polygalacturonic acid (PGA), oligogalacturonides, pectins extracted from A. thaliana cell walls and to structurally related alginates. Our results suggest that both ionic and steric interactions are required to match the relatively linear pectin backbone. Binding of WAK(67-254) to PGA, oligogalacturonides and alginates occurred only in the presence of calcium and in ionic conditions promoting the formation of calcium bridges between oligo-and polymers (also known as 'egg-boxes'). The conditions inhibiting the formation of calcium bridges (EDTA treatment, calcium substitution, high NaCl concentrations, depolymerization and methylesterification of pectins) also inhibited the binding of WAK(67-254) to calcium-induced egg-boxes. The relevance of this non-covalent link between WAK(67-254) and cell wall pectins is discussed in terms of cell elongation, cell differentiation and host-pathogen interactions.

Arabidopsis↗
PubMed2002

F-actin-dependent endocytosis of cell wall pectins in meristematic root cells. Insights from brefeldin A-induced compartments.

Brefeldin A (BFA) inhibits exocytosis but allows endocytosis, making it a valuable agent to identify molecules that recycle at cell peripheries. In plants, formation of large intracellular compartments in response to BFA treatment is a unique feature of some, but not all, cells. Here, we have analyzed assembly and distribution of BFA compartments in development- and tissue-specific contexts of growing maize (Zea mays) root apices. Surprisingly, these unique compartments formed only in meristematic cells of the root body. On the other hand, BFA compartments were absent from secretory cells of root cap periphery, metaxylem cells, and most elongating cells, all of which are active in exocytosis. We report that cell wall pectin epitopes counting rhamnogalacturonan II dimers cross-linked by borate diol diester, partially esterified (up to 40%) homogalacturonan pectins, and (1-->4)-beta-D-galactan side chains of rhamnogalacturonan I were internalized into BFA compartments. In contrast, Golgi-derived secretory (esterified up to 80%) homogalacturonan pectins localized to the cytoplasm in control cells and did not accumulate within characteristic BFA compartments. Latrunculin B-mediated depolymerization of F-actin inhibited internalization and accumulation of cell wall pectins within intracellular BFA compartments. Importantly, cold treatment and protoplasting prevented internalization of wall pectins into root cells upon BFA treatment. These observations suggest that cell wall pectins of meristematic maize root cells undergo rapid endocytosis in an F-actin-dependent manner.

ADP-Ribosylation Factor 1↗
PubMed1994

The effect of pectin on the gastric emptying rates and blood glucose levels after a test meal.

This study was designed to evaluate the effect of pectin given in a palatable form on the gastric emptying rates of the solid and liquid phases of a test meal and to ascertain whether pectin affected blood glucose levels in ten healthy male and female volunteers. Gastric emptying was measured using dual isotope gamma scintigraphy. Allocation to the treatment group was double-blind and randomized. Sequential blood sampling was used to measure blood glucose levels. The times for the stomach to empty half the radiolabelled meal were similar after both pectin and placebo; however, a significant difference was seen between the AUC values of the meal between the two treatments. This can be attributed to the divergence of the emptying curves after the time point at which 50% of the meal had emptied, as pectin delayed the emptying of the last 20% of the meal. The initial phase of emptying for both pectin and placebo was significantly faster than the meal. No significant difference was found between blood glucose levels when either pectin or placebo was administered.

Blood Glucose↗
PubMed1993

Isolation and characterization of an extracellular glycosylated protein complex from Clostridium thermosaccharolyticum with pectin methylesterase and polygalacturonate hydrolase activity.

An extracellular protein complex was isolated from the supernatant of a pectin-limited continuous culture of Clostridium thermosaccharolyticum Haren. The complex possessed both pectin methylesterase (EC 3.1.1.11) and exo-poly-alpha-galacturonate hydrolase (EC 3.2.1.82) activity and produced digalacturonate from the nonreducing end of the pectin chain. The protein consisted of 230- and 25-kDa subunits. The large subunit contained 10% (wt/wt) sugars (N-acetylgalactosamine and galactose). Under physiological conditions both activities acted in a coordinated manner: the ratio between methanol and digalacturonate released during degradation was constant and equal to the degree of esterification of the pectin used. Prolonged incubation of the enzyme with pectin led to a nondialyzable fraction that was enriched in neutral sugars, such as arabinose, rhamnose, and galactose; the high rhamnose/galacturonic acid ratio was indicative of hairy region-like structures. The smallest substrate utilized by the hydrolase was a tetragalacturonate. Vmax with oligogalacturonates increased with increasing chain length. The Km and Vmax for the polygalacturonate hydrolase with citrus pectate as a substrate were 0.8 g liter-1 and 180 mumol min-1 mg of protein-1, respectively. The Km and Vmax for the esterase with citrus pectin as a substrate were 1.2 g liter-1 and 440 mumol min-1 mg of protein-1, respectively. The temperature optima for the hydrolase and esterase were 70 and 60 degrees C, respectively. Both enzyme activities were stable for more than 1 h at 70 degrees C. The exo-polygalacturonate hydrolase of Clostridium thermosulfurogenes was partially purified while the methylesterase was also copurified.

Amino Acid Sequence↗