Immobilisation of a hydroperoxide lyase and comparative enzymological studies of the immobilised enzyme with membrane‐bound enzyme

Abstract

Hydroperoxide lyase is the key enzyme in lipoxygenase pathway producing green-note flavours and has potential value for the flavour additive industry. So far, only a low yield of green-note flavours produced by hydroperoxide lyase has been achieved, primarily because of its instability. The aim of this study was to stabilise hydroperoxide lyase from Amaranthus tricolor leaves by immobilisation and investigate the characteristics of immobilised enzyme in comparison with free and native membrane-bound enzyme. A maximum activity of 2.85±0.1 U g(-1) (wet) ceramic hydroxyapatite and a yield of 80% were obtained under optimised coupling conditions. The optimal reaction pH was 6.0, 6.0 and 7.5 for free, membrane-bound and immobilised enzyme respectively, while the optimal reaction temperature was 30, 35 and 35 °C respectively. Thermal and operational stability of immobilised enzyme were substantially enhanced. However, a higher substrate diffusion resistance was imposed after immobilisation, as evidenced by the Km value of immobilised enzyme being higher than that of free and membrane-bound enzyme. Ceramic hydroxyapatite was a candidate for the immobilisation of hydroperoxide lyase from A. tricolor leaves. The stability of hydroperoxide lyase was substantially improved after immobilisation on this substrate.