Journal
JOURNAL OF BIOSCIENCE AND BIOENGINEERING
Volume 128, Issue 2, Pages 135-141Publisher
SOC BIOSCIENCE BIOENGINEERING JAPAN
DOI: 10.1016/j.jbiosc.2019.01.017
Keywords
N-Acetylhexosaminidase; Streptomyces alfalfa; N-Acetyl-D-glucosamine; Enzymatic conversion; Chitin
Funding
- National Key Research and Development Program of China [2017YFD0201100]
- Science Project Grant for Oversea Personnel in Hebei Province [CP2015005015]
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture of China
- Innovation projects on the course of Biotechnology in Hebei province, China [2012GJJG054, 201202]
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N-Acetyl-D-glucosamine (GlcNAc) is a valuable monosaccharide widely used in the medical, agricultural, biofuel, and food industries. Its efficient and environment-friendly production depends on the binary system of beta-N-acetylhexosaminidase (HEX) and chitinase. In the present study, a HEX of glycoside hydrolasefamily 20 was identified in Streptomyces alfalfae ACCC40021, and was overexpressed in Escherichia coli. The purified recombinant SaHEX showed maximal activities at 60 degrees C and pH 5.5, and retained stable up to 45 degrees C. The enzyme not only exhibited broad substrate specificity including p-nitrophenyl beta-N-acetylglucosaminide, p-nitrophenyl beta-N-acetylgalactosaminide, chitooligosaccharides and colloidal chitin, but also had higher specific activities (up to 1149.7 +/- 72.6 U/mg) towards natural and synthetic substrates. When combined with a commercial chitinase, it achieved a conversion rate of 93.7% from 1% of colloidal chitin to GlcNAc in 6 h, with the product purity of >98%. These excellent properties make SaHEX a potential enzyme candidate for the chitin conversion for various industrial purposes. (C) 2019, The Society for Biotechnology, Japan. All rights reserved.
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