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

Sci Rep. 2016 Aug 24:6:32081. doi: 10.1038/srep32081.

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, ΔG(*) (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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus / enzymology*
  • Bacillus / genetics
  • Catalytic Domain
  • Escherichia coli / genetics
  • Glycine / chemistry
  • Glycosylation
  • Hydrogen-Ion Concentration
  • Kinetics
  • Protein Conformation
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Sequence Analysis, Protein
  • Substrate Specificity
  • Sucrose / metabolism*
  • Temperature
  • Thermodynamics
  • beta-Fructofuranosidase / chemistry*
  • beta-Fructofuranosidase / genetics
  • beta-Fructofuranosidase / metabolism*

Substances

  • Recombinant Proteins
  • Sucrose
  • beta-Fructofuranosidase
  • Glycine