Characterization of a novel low-temperature-active, alkaline and sucrose-tolerant invertase.

ABSTRACT: A glycoside hydrolase family 32 invertase from Bacillus sp. HJ14 was expressed in Escherichia coli. The purified recombinant enzyme (rInvHJ14) showed typical biochemical properties of low-temperature-active and alkaline enzymes: (i) rInvHJ14 was active and stable in the range of pH 7.0-9.5 with an apparent pH optimum of 8.0; (ii) rInvHJ14 was most active but not stable at 30-32.5?°C, with 19.7, 48.2 and 82.1% of its maximum activity when assayed at 0, 10 and 20?°C, respectively, and the Ea, ?G(*) (30?°C), Km (30?°C) and kcat (30?°C) values for hydrolysis of sucrose by rInvHJ14 was 47.6?kJ mol(-1), 57.6?kJ mol(-1), 62.9?mM and 746.2?s(-1), respectively. The enzyme also showed strong sucrose tolerance. rInvHJ14 preserved approximately 50% of its highest activity in the presence of 2045.0?mM sucrose. Furthermore, potential factors for low-temperature-active and alkaline adaptations of rInvHJ14 were presumed. Compared with more thermostable homologs, rInvHJ14 has a higher frequency of glycine residues and a longer loop but a lower frequency of proline residues (especially in a loop) in the catalytic domain. The catalytic pockets of acid invertases were almost negatively charged while that of alkaline rInvHJ14 was mostly positively charged.

SUBMITTER: Zhou J 

PROVIDER: S-EPMC4995436 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature