Pectate solutions

A unit of activity is arbitrarily defined as that amount of enzyme that will reduce the viscosity of the sodium pectate solution by 50% in a 5-min period. The time required to reach A = 50% is typically inversely proportional to the concentration of enzyme (Mill and Tuttobello, 1961 Gusakov et al., 2002). 

The results presented here on pectate solutions containing calcium or copper ions bring interesting evidence for an anomalous behavior of pectate properties in the range of ion to polymer ratio below that corresponding to the massive phase separation. The possibility that a conformational change proceeds along with the interaction with divalent ions is examined and discussed in comparison with the case of the proton-induced conformational transition. 

Figure 7. Rheogram of pectate solutions containing glu-cono-lactone and CaEDTA at 25°C, Left, a-c Lissalous figures obtained at different times during the course of the hydrolysis reaction. Right time course of the complex viscosity components, and of the viscous. i, l, and elastic, n",l, components of...

The viscosity of sodium pectinate was previously examined by Pals and Hermans [44]. In salt excess (NaCI 0.1 M), the viscosity of a pectate sodium form solution (ri) is related to the polymer concentration (c) and the molecular weight (or [rj] = KM ) by the relation ... 

At end, it is important to mention that calcium pectate gel beads were compared with calcium alginates gel beads for all entrapment uses [65, 66] in this work, the authors determined the pore size of the beads by size exclusion chromatography using dextran standards and other solutes. 

The use of polyethylene glycol ethers in a process in which a high viscosity emulsion is formed on contact with residual crude oil has also been tested as a means of plugging thief zones using surfactants (248-250). Precipitation of sodium pectate when fresh water solutions contact brine has been proposed as a method of plugging high permeability zones (251). 

For three endo-D-galacturonanases, isolated from the culture filtrate of Coniothyrium diplodiella,114-116 that differed in the extent of degradation of sodium pectate, a 50% decrease of viscosity of the substrate solution corresponded to the splitting of 3, 4, and 10% of the glycosidic bonds, respectively. A similar difference was found between two endo-D-galacturonanases isolated from tomatoes117 one... 

TiTany commercial uses of carbohydrates depend upon reversible inter- actions of the hydroxyl groups with ions to form complexes. The processes are intricate, and analyses of the equilibria involved have been difficult or impossible (I). For example, the nature of the complexes involving polysaccharides and polyanions, such as borate, can only be hypothesized (2). Similarly the gelling of pectates with Ca(II) (3), the reactions of heptono-y-lactones with Fe(III), or the nature of Fe(III)-dextran complexes in intramuscular injectable solutions are awaiting proper description. Although the systems involving monomeric components are more amenable to study, as for the reactions of metal salts or hydroxides with monosaccharides or their simple derivatives (4,5, 6, 7)... 

At the optimal sodium pectate concentration, the efflux time of the substrate solution in the viscometer should be in the range of 115 to 120 sec. 

Set up a third reaction system using heat-inactivated enzyme diluted in 20 mM sodium acetate buffer alone (no sodium pectate substrate solution). Use the efflux time of this reaction as V%. 

Detoxication of Metals. Pectins or pectin derivatives have been proposed as antidotes for heavy metal poisoning for nearly 200 years. Kertesz (9) has reviewed the early work in this area. Pectin complexes lead so strongly as to quantitatively remove it from solution. Absorption 6f lead, arsenic, and selenium by several animal species has been reduced by pectin- or apple-containing diets. Use of pectin as a prophylactic agent in lead poisoning continues to be of interest. Bondarev (88) recently reported an increase in excretion and a decrease in bone accumulation of lead when rats fed 6 mg/day of lead also received 72-432 mg/day of low ester pectin. Paskins-Hurlburt et al. (89) achieved an 87% decrease in lead absorption by pectate fed rats. These studies bear out the early observations of Fellenburg (see 9, p. 572), who concluded that pectin of decreased ester content would have an enhanced ability to complex metals. 

Enzyme Solution Mix pectate lyase with Tris Buffer Solution to achieve a 1 100 solution. 

Pectinesterase action was first reported in 1840 by Fremy (56). He noted that the addition of carrot juice to a pectin solution caused formation of a gel. This gel was produced by the enzymatic deesterification of pectin followed by precipitation of the resulting polygalacturonic acid as calcium pectate 20), Various names such as pectin meth-oxylase and pectin methyl esterase have been applied to the enzyme, but pectinesterase is the preferred trivial name (57). 

Paoletti, S., Cesaro, A., Delben, F., and Ciana, A. 1986. Ionic effects on the conformation, equilibrium, properties, and rheology of pectate in aqueous solution and gels, in Chemistry and Function of pectins, eds. M. L. Fishman and J. J. Jen, pp. 73-87, ACS Symposium Series, American Chemical Society, Washington, DC. 

The behaviour of pectic substances in solutions involves both short and long range interactions among all the constituents of the macromolecule as well as interactions with the solvent molecules and the ions in the solutions. The calculations reported here explain the aggregation of PGA chains in acidic media as due to the formation of a network of inter-intra chain hydrogen bonds. Also the gel formation of Na- and Ca-Pectate is well reproduced. 

Because of the polyelectroly tic nature, pectin solutions need to be made in excess of salt, usually in 0.05 0.1 M sodium chloride or phosphate, and use the same solvent for dilution (isoionic dilution) (Pals and Hermans, 1952). This is because, unlike neutrol polymers, the viscosity of dilute solution of polyelectrolytes displays unique dependence on concentration. As shown in Figure 9.5, the qsp of sodium pectate exhibits a maximum in pure water and low concentration of salt, a phenomenon caused by the so-called electroviscous effect. When the salt concentration is... 

Fig. 13. Operational stability of D-amino acid oxidase fixed in cells of Trigonopsis variabilis CCY 15-1-3 entrapped in standard (A) and hardened (a) calcium pectate gel and standard (O) and hardened calcium alginate gel ( ). The relative activity was monitored by continuous processing, with the substrate (cephalosporin C) solution in the flow microcalorimeter [39]...

After boiling, the goods are washed with water, and then treated with a dilute solution of hydrochloric acid (1 -5 to 2 per cent). This liberates the fatty acids from the lime soaps and pectic acid from the pectates, with the formation of calcium chloride. The goods are then rinsed to remove the calcium chloride and returned to the kier where they are boiled again with sodium carbonate and rosin or a high-titre soap. The free fatty and pectic acids are now converted into their soluble sodium salts which can be washed away with water. 

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