Calcium pectate gels

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. 

Figure 7. The egg-box structure for the junction zones of dilute calcium pectate gels two galacturonan chains in the twofold (2i) helical conformation with calcium ions (shaded circles) locked between them.

Figure 9. The cable model for the structure of concentrated calcium pectate gels. Egg-box dimers link single-chains segments (top left) and are themselves ed together by larger aggregates of either egg-box or 3i helical chains (lower right)...

Thus pectins in muro contain most elements of the cable model but have additional features due to esterification (acetyl- as well as methyl-) and branching. The ionic junction zones are similar to those of calcium pectate gels in vitro but also contam methyl-esterified junctions, and most of the single chains probably have a relatively high degree of methyl-esterification. 

The development of modem separation techniques has affected the purification procedures employed for D-galacturonanases. Fractional precipitation with ammonium sulfate and with organic solvents are now used only in combination with new separation techniques. To separate fractions having D-galacturonanase activity, adsorption to pectate or calcium pectate gel has been used in several instances.157-207... 

Endogenous pectin esterases play an important role in citrus processing they have therefore been studied intensively. They cause cloud loss in citrus juices, which is due to the calcium precipitation of enzymatically de-esterified pectin. This is desirable in the production of lemon and lime juices but undesirable in the production of orange juice. In orange juice concentrates strong calcium pectate gels may form which cannot be reconstituted... 

M.D. Walkinshaw and S. Araott, Conformations and Interactions of Pectins. II. Models for Jimction Zones in Pectinic Acid and Calcium Pectate Gels. J. Mol. Biol., 153 (1981) 1075. 

Walkinshaw, M.D. and Arnott, S. 1981b. Conformations and interactions of pectins. II. Models for junction zones in pectinic acid and calcium pectate gels,. /. Mol. Biol., 153 1075-1085. 

Table 2. Intrinsic rate constant and effectiveness factor values of D-amino acid oxidase immobilized in calcium pectate gel studied by flow micro calorimetry [28]...

In spite of usefulness of the simplification obtained by decreasing the experimental substrate concentration, many studies are aimed at the investigation of kinetic properties of immobilized biocatalysts within broader concentration ranges. In a previous paper [29], cells of Escherichia coli with penicillin acylase activity were immobilized by entrapment in calcium pectate gel and tested on the transformation of penicillin G to 6-amino penicillanic acid. Figure 9 shows experimental data from a microcalorimetric investigation of the penicillin G transformation in steady state. As appreciable particle-mass transfer was expected, the mathematical model that includes particle-mass balance was used. 

Fig. 9. Kinetic measurement of the calcium pectate gel immobilized penicillin acylase in the flow microcalorimeter. Cell loading concentrations (mg of dry weight per mL of gelling suspension) ( ) 11.9 ( ) 23.7 ( ) 29.6 [29]...

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]...

Figure 1.20. Cumulative release of indomethacin from a calcium pectate gel in citrate buffer in the presence (circles) and absence (squares) of pectinolytic enzyme (data from ref. (263))...

Whole cells of the bacterium Nocardia tartaricans with hydrolytic achvity toward ds-epoxysuccinate were encapsulated in a carrier material consisting of sodium alginate, cellulose sulfate, and poly(methylene-co-guanidine) for the production of L-(+)-tartrate. The encapsulation led to improved performance of the cells in terms of EH activity and storage stability when compared to the cells that were entrapped in calcium pectate gel beads [68]. 

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