Biochemical Characterization of a Novel GH86 ��-Agarase Producing Neoagarohexaose from Gayadomonas joobiniege G7

• DOI: 10.4014/jmb.1710.10011
• Publication Date: 2018-02-28T09:14:48Z
• Authors: Yeong Rim Lee; Subin Jung; Won-Jae Chi; Chang-Hwan Bae; Byeong-Chul Jeong; Soon-Kwang Hong; Chang-Ro Lee
• Keywords: Agarose; Zymography; Hydrolase; Agarose gel electrophoresis

A novel β-agarase, AgaJ5, was identified from an agar-degrading marine bacterium, Gayadomonas joobiniege G7. It belongs to the glycoside hydrolase family 86 and is composed of 805 amino acids with a 30-amino-acid signal peptide. Zymogram analysis showed that purified AgaJ5 has agarase activity. The optimum temperature and pH for AgaJ5 activity were determined to be 30°C and 4.5, respectively. AgaJ5 was an acidic β-agarase that had strong activity at a narrow pH range of 4.5-5.5, and was a cold-adapted enzyme, retaining 40% of enzymatic activity at 10°C. AgaJ5 required monovalent ions such as Na+ and K+ for its maximum activity, but its activity was severely inhibited by several metal ions. The Km and Vmax of AgaJ5 for agarose were 8.9 mg/ml and 188.6 U/mg, respectively. Notably, thin-layer chromatography, mass spectrometry, and agarose-liquefication analyses revealed that AgaJ5 was an endo-type β-agarase producing neoagarohexaose as the final main product of agarose hydrolysis. Therefore, these results suggest that AgaJ5 from G. joobiniege G7 is a novel endo-type neoagarohexaose-producing β-agarase having specific biochemical features that may be useful for industrial applications.