The impact of calcium ions on commercially available β-galactosidase
2017
Zolnere, K., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology. Dept. of Food Technology | Liepins, J., University of Latvia, Riga (Latvia). Inst. of Microbiology and Biotechnology | Ciprovica, I., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology. Dept. of Food Technology
Commercial lactose hydrolysing enzymes producers provide purchasers with information as optimal enzyme temperature and pH, as well recommended amount of enzyme. However, there are also other indices in food substrate which might have impact on enzyme activity. The cations concentration in the substrate is the one of those. Whey is a dairy by-product with a relatively high Ca 2+, K + and Na + ions concentration. These cations (especially Ca 2+) are added in cheese making and remain in whey in comparatively large amounts. Moreover, Na + also remains in whey since salt is added for cheese grains salting. The aim of the study is to determine the impact of Ca 2+ ions on commercially available β -galactosidase. The effect of Ca 2+ ions on commercial β -galactosidase (NOLA Fit5500, Ha -Lactase 5200, Chr. HANSEN, Denmark; Lactozym® Pure 6500 L, Novozymes, Denmark) were tested. For investigation of the effect of Ca 2+ ions on the β -galactosidase activity, chromogenic lactose substare – oNPG (2-nitrophenyl β -D-galactopyranoside; Sigma, Germany) was used, reactions were carried out at pH 6.6, using 0.1 M Tris-HCl buffer, and Ca 2+ ions concentration range 5 – 50 mM. The enzymatic reactions were measured spectrophotometrically at 410 nm using Tecan 96-well plate reader (Tecan Group, Switzerland).The results imply, that Ca 2+ ions alone do not have effect on lactose hydrolysis, moreover, in some they even stimulate it (NOLA Fit5500). The study results will help to precisely adjust the amount of commercially available enzymes to dairy substrates with high cations content.
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