The interaction of zinc(II) and phytic acid with soya bean glycinin

Binding of phytic acid to Zn(II) free glycinin was not observed in 0.5 M KCl at pH 6.2. The addition of varying quantities of phytic acid to a Zn(II)- glycinin system at pH 6.2 ([KCl]=0.5 M ) initially resulted in binding of phytate and increased binding of Zn(II) to glycinin probably as a phytate-Zn(II)-glycinin complex. Further addition of phytate resulted in precipitation of zinc and protein. Bovine serum albumin also showed increased affinity for Zn(II) owing to the presence of phytic acid. Phytic acid-Zn(II) precipitates have a capacity of removing glycinin from solution, presumably by surface adsorption. The presence of soluble Zn(II) inhibits this adsorption. Bovine serum albumin is removed from solution by phytic acid-Zn(II) precipitates only when soluble zinc is present.