The Studies On Preparation And Functional Properties Of Oligomeric Glutamate Calcium

In this paper, poly(γ- glutamic acid) (γ-PGA) was produced by B53 (Bacillus subtilis53) fermentation. Then ethanol and acetone were used to precipitate the broth. PGA was extracted through centrifugal effect. In order to eliminate the ion, dialysis method was used. Finally,the finished product was obtained by freeze-drying. The molecular weight of the PGA we got was between 100 000 and 1 000 000. It was not suitable to be as medical carrier the molecular weight of which was between 20 000 and 60 000. So it was hydrolyzed under the conditions of pH value 3.0 and the temperature 80℃for 8 hours. PGA was hydrolyzed to oligomeric glutamic acid. After that, the oligomeric glutamic acid was obtained by separating with ultra-filtration membrane and purificating and freeze-drying, the molecular weight of which was between 10 000 and 10 0000. This point was proven by SDS-PAGE.The pure oligomeric glutamic acid and CaCl2 were used to prepare oligomeric glutamate calcium. Do the single factor tests to study the factor with greater effect on ration of complex and find that the important factors were mass ratio of oligomeric glutamate and calcium, pH and reaction temperature. Then do orthogonal experimental design to optimize reaction condition and find the optimum condition. It was ratio of amino acid to calcium chloride 9:4(w/w), pH value 5.0, the temperature 80℃, reaction time 60 min. The chelating ratio was up to 91.05%. At last,by evaluating the infrared spectrum variety, the formation of oligomeric glutamate calcium can be confirmed.The experiment of calcium metabolism of oligomeric glutamate calcium was performed on the mice. Thirty KM mice were divided into 3 groups, 10 each.Group I fed low calcium diet;GroupⅡfed low calcium diet + 0.2 mL calcium carbonate liquid(8 mg/mL); GroupⅢfed low calcium diet + 0.2 mL oligomeric glutamate calcium liquid(8 mg/mL). Fed 3 weeks and made calcium metabolism tests for 3 days.The result was that the absorption of the calcium carbonate group was 20% higher than that of the control group. The absorption of the oligomeric glutamate calcium group was 42% higher than that of the control group and 20% than calcium carbonate group. It indicated that the absorption rate of the oligomeric glutamate calcium group was high because oligomeric glutamate calcium had good solubility and could release calcium ion continually and slowly.The calcium level in blood serum of the oligomeric glutamate calcium group and calcium carbonate group was significantly higher than that of the control group (P<0.01) and the oligomeric glutamate calcium group was higher in certain degree than calcium carbonate group (P>0.05).So oligomeric glutamate calcium had good effect on calcium supplement.The length, the weight and the calcium content of femoral bone of the oligomeric glutamate calcium group and calcium carbonate group was significantly higher than that of the control group (P<0.01). The calcium content of femoral bone of the oligomeric glutamate calcium group was significantly higher than that of calcium carbonate group (P<0.01). It showed that oligomeric glutamate calcium had better utilization in bone tissue and can be developed as a good source of calcium.