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Stability of glucose oxidase and catalase adsorbed on variously activated 13X zeolite
Author(s) -
Pifferi P. G.,
Vaccari A.,
Ricci G.,
Poli G.,
Ruggeri O.
Publication year - 1982
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260241004
Subject(s) - citric acid , chemistry , glucose oxidase , adsorption , catalase , zeolite , enzyme , nuclear chemistry , inorganic chemistry , phosphate , biochemistry , catalysis , organic chemistry
Abstract The use of 13X zeolite (0.1‐0.4‐mm granules), treated with 2 N and 0.01 N HCI, 0.01 M citric acid, 0.1 M citric‐phosphate buffer (pH 3.6), and in untreated form to adsorb glucose oxidase of fungal origin and microbial catalase was examined. Physicochemical analysis of the support demonstrated that its crystalline structure, greatly altered by the HCl and buffer, could be partially maintained with citric acid. The specific adsorption of the enzymes increased with decreasing pH and proved to be considerable for all the supports. The stability with storage at 25°C is strictly correlated with the titrable acidity of the activated zeolite expressed as meq NaOH/g and with pH value of the activation solution. It proved to be lower than 55 h for both enzymes if adsorbed on zeolite treated with 2 N HCl, and 15‐fold and 30‐fold higher for glucose oxidase and catalase adsorbed, respectively, on zeolite treated with the 0.1 M citric‐phosphate buffer and 0.01 M citric acid. The specific adsorption of glucose oxidase and catalase was, respectively, 1840 U/g at pH 3.0 and 6910 U/g at pH 5.0. Their half‐life at 25°C with storage at pH 3.5 for the former and at pH 5.0 for the latter was 800 and 1560 h vs. 40 and 110 h for the corresponding free enzymes.