Na pectate

On the middle curve are situated Na arabinate, Na pectinate, Na semen lini-mucilage and Na pectate all having carboxyl groups. They will be called carboxyl colloids. 

Fig. 14 gives the ion spectra for three carboxyl colloids. The data for the third one, Na-pectate, are very incomplete because of technical difficulties. 

On account of great technical difficulties only a very restricted number of cations were investigated with Na pectate. 

Fig. 17. Reversal of charge spectra of Na pectate (carboxyl colloid) and of egg lecithin and alcohol soluble soya bean phosphatide (phosphate colloids) with alkali chlorides (and NH4CI).

Table 1 shows some biochemical properties of the pectolytic enzymes present in pool 1. The pectin lyase/pectate lyase activities (pool I) and polygalacturonase activity (pool II) were not significantly affected by NH4+, Na+ and K+ (0,25 - 2,5mM), while Al +, p-mercaptoethanol, Hg2+, EDTA, Ba + and Zn+2 (2,5mM) inhibited 30-100% these activities. On the other hand, Ca2+, Mg + and Mn + at 2,5mM concentration activated 20-100% pectin/pectate lyases but Ca " " and Cu " " (2,5mM) inhibited polygalacturonase activity about 42 - 70%. 

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. 

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