Purification and characterization of a glutaminase from Lactobacillus reutri KCTC 3594

초록

In this study we attempted to optimize conditions of purifying glutaminase from Lactobacillus reuteri KCTC3594 and to investigate the properties of the enzyme. When the cells of L. reuteri were extracted with high pressure of 15,000 psi three times, the crude extract containing supernatant showed the maximum glutaminase activity, 15.515 U/ml. Glutaminase was purified approximately 20.67-fold with a yield from the cell-free extract of L. reuteri KCTC3594 by protamine sulfate treatment and chromatography methods including anion exchange and gel filtration [1]. The sizes of a major unit and a subunit of the enzyme were presumed 45 kDa and 60 kDa, respectively, by SDS-PAGE. The enzyme activity was optimal at 40 ℃ and pH 7.5, respectively. It was shown that the glutaminase was salt-tolerant as the activity was maintained 50 % at 15 % (w/v) salt. On the other hand, the enzyme was significantly inhibited up to 80% by DON (10 mM) and iodoacetate (50 mM). The glutaminase of L. reuteri can be partially purified by previous methods and showed most of properties were similar with those of other bacteria [2]. In addition, it has high salt-tolerance. The purified glutaminase can be used in food and pharmaceutical industries. References [1] Durà, M.A., Flores, M. and Toldra, F. Purification and characterisation of a glutaminase from Debaryomyces spp. (2002) Int J Food Microbiol 76, 117 – 126. [2] Masuo, N., Yoshimune, K., Ito, K., Matsushima, K., Koyama, Y. and Moriguchi, M. (2005) Micrococcus luteus K-3-type glutaminase from Aspergillus oryzae RIB40 is salt - tolerant. J Biosci Bioeng 100, 576 – 578.