Immobilization of gamma-glutamyl transpeptidase [prepared from bovine kidneys], a membrane enzyme, in gel beads via liposome entrapment
1994
Gotoh, T. (Akita Univ. (Japan)) | Shidara, M. | Iwanaga, T. | Kikuchi, K. | Hozawa, M.
Bovine kidney gamma-glutamyl transpeptidase, a membrane enzyme, was immobilized in gel beads by application of the method of Wallsten et al. The gel beads were equilibrated with a dispersion of the enzyme, phospholipids, and cholate and subsequently dialyzed against a buffer for reconstitution and immobilization of enzyme-bound liposomes in the pores of the beads. From the standpoints of the immobilized contents of protein and phospholipids and of the reactivity of gamma-glutamyl transpeptidase, a dialysis buffer of Tris-HCl (pH 7.5), a phospholipid concentration of 45 mg/ml in the enzyme-phospholipidcholate dispersion, and the use of Sepharose CL-6B as the support gel were found to be most appropriate for the immobilization of gamma-glutamyl transpeptidase. gamma-Glutamyl transpeptidase was activated and stabilized by reconstitution in liposomes. In operation with a packed bed reactor, liposome-bound gamma-glutamyl transpeptidase immobilized in Sepharose CL-6B exhibited relatively stable and constant activity for 13 h. In addition, it was found that enzyme substrates were able to pass through the pores of the gel beads to interact with the enzyme present on the outer surface of the liposome membrane in the gel beads. These results thus indicated that a novel support made up of liposomes and Sepharose CL-6B would permit efficient immobilization of lipid-requiring and/or membrane enzymes
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