Abstract: The ability of poly-γ-glutamic acid(γ-PGA)to retard calcium phosphate depositing was investigated in the study. When 200 mg/Lγ-PGA was added, it remarkably reduced the calcium phosphate depositing by 83.4%, and retarded the time of achieving the highest depositing to 20 min. The chelation conditions ofγ-PGA with calcium ion such as pH, temperature and the concentration of γ-PGA were studied. Results showed that the maximum yield of chelation was gained under the condition of temperature 37 ℃, pH 6.0, 3% γ-PGA and the molar ratio of carboxyl group ofγ-PGA to calcium ion 2.5:1, then the chelation course was finished within 15 min and the content of calcium was 11.06% in the chelate complex. It illustrated thatγ-PGA was able to chelate with calcium ion and worth exploiting as a new calcium supplemental agent.

Key words: poly-&gamma, -glutamic acid； calcium ion； retarding calcium phosphate depositing； yield of chelation；