A novel α-galactosidase from the thermophilic probiotic Bacillus coagulans with remarkable protease-resistance and high hydrolytic activity

PLoS One. 2018 May 8;13(5):e0197067. doi: 10.1371/journal.pone.0197067. eCollection 2018.

Abstract

A novel α-galactosidase of glycoside hydrolase family 36 was cloned from Bacillus coagulans, overexpressed in Escherichia coli, and characterized. The purified enzyme Aga-BC7050 was 85 kDa according to SDS-PAGE and 168 kDa according to gel filtration, indicating that its native structure is a dimer. With p-nitrophenyl-α-d- galactopyranoside (pNPGal) as the substrate, optimal temperature and pH were 55 °C and 6.0, respectively. At 60 °C for 30 min, it retained > 50% of its activity. It was stable at pH 5.0-10.0, and showed remarkable resistance to proteinase K, subtilisin A, α-chymotrypsin, and trypsin. Its activity was not inhibited by glucose, sucrose, xylose, or fructose, but was slightly inhibited at galactose concentrations up to 100 mM. Aga-BC7050 was highly active toward pNPGal, melibiose, raffinose, and stachyose. It completely hydrolyzed melibiose, raffinose, and stachyose in < 30 min. These characteristics suggest that Aga-BC7050 could be used in feed and food industries and sugar processing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus coagulans / enzymology*
  • Enzyme Stability
  • Hydrolysis
  • Nitrophenylgalactosides / chemistry
  • Peptide Hydrolases / chemistry*
  • Probiotics / chemistry*
  • Substrate Specificity
  • alpha-Galactosidase / chemistry*
  • alpha-Galactosidase / isolation & purification

Substances

  • Nitrophenylgalactosides
  • 4-nitrophenylgalactoside
  • alpha-Galactosidase
  • Peptide Hydrolases

Grants and funding

This research was financially supported by grants from the National Natural Science Foundation of China (No. 31270145), the National Fund for Fostering Talents of Basic Sciences (J1103513), and Research (Innovative) Fund of Laboratory of Wuhan University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.