Proteic feeder effect on glucose oxidase aggregates formation

Abstract

In this study, it is aimed to prepare cross-linked glucose oxidase (GOD) aggregates by using different proteic feeders. Bovine serum albumin (BSA), gelatine and collagen were used separately as proteic feeders in the aggregate preparation process. The initial enzyme concentration was kept constant as 0.05 mg/ml. The amount of BSA varied from 1 to 50 mg and the amount of gelatine and collagen were in the range of 5- 75 mg. A cross-linker, glutaraldehyde (2 % v/v) has been used in order to form GOD aggregates with proteic feeder. The highest immobilization efficiency was found when BSA feeder was used. Activities of both free and immobilised GOD were obtained by measuring the amount of hydrogen peroxide formed from glucose conversion, by using spectrophotometer. The maximum activities were obtained at following proteic feeder amounts: BSA 5 mg, collagen 60 mg, gelatine 50 mg. Kinetic parameters of native and immobilised enzyme have been calculated by using Lineweaver-Burk plots in the substrate range of 0.01-1 M . The maximum reaction rates for free and immobilised enzyme with different proteic feeders, BSA, gelatine and collagen were calculated as 66.29, 12.22, 9.29, 4.53 mM/$min^ {-1}$, respectively. The corresponding saturation constants of systems with the maximum activity were 7.9, 11.37, 22.58, 33.6 mM, respectively.