Kang Hee-Kyoung, Kim Seung Heuk, Park Ji-Young, Jin Xing-Ji, Oh Deok-Kun, Kang Seong Soo, Kim Doman
Laboratory of Functional Carbohydrate Enzymes and Microbial Genomics, Institute of Bioindustrial Technology, Chonnam National University, Gwang-Ju 500-757, South Korea.
Yeast. 2005 Nov;22(15):1239-48. doi: 10.1002/yea.1311.
A dextranase-encoding cDNA from L. starkeyi KSM22 was isolated and characterized. The 2052 bp cDNA fragment (lsd1) harbouring the dextranase gene exhibited one open reading frame (ORF) composed of 1824 bp flanked by a 41 bp 5'-UTR and a 184 bp 3'-UTR, including a 27 bp poly(A) tail. The lsd1 gene contains no introns. The open reading frame encodes a 608 amino acid polypeptide (LSD1) with a 67.6 kDa predicted molecular mass. There was a 77% deduced amino acid sequence identity between the LSD1 dextranase and the dextranase from Penicillium minioluteum. The primary structure of LSD1 dextranase exhibits distant similarity with the enzymes of the glycosyl hydrolase family 49 that comprises Penicillium dextranase. The optimum pH of LSD1 was 6.0 and the optimum temperature was 37 degrees C. LSD1 dextranase activity was substantially abolished by exposure to 1 mM Hg2+, Ag3+ and Mn2+. LSD1 exhibited high hydrolysing activity towards dextran (100%), soluble starch (22%) and mutan (8%).
从斯氏假丝酵母KSM22中分离并鉴定了一个编码葡聚糖酶的cDNA。含有葡聚糖酶基因的2052 bp cDNA片段（lsd1）表现出一个由1824 bp组成的开放阅读框（ORF），两侧分别是41 bp的5'-UTR和184 bp的3'-UTR，包括一个27 bp的poly(A)尾。lsd1基因不含内含子。该开放阅读框编码一个608个氨基酸的多肽（LSD1），预测分子量为67.6 kDa。LSD1葡聚糖酶与微小青霉的葡聚糖酶之间推导的氨基酸序列同一性为77%。LSD1葡聚糖酶的一级结构与包含青霉葡聚糖酶的糖基水解酶家族49的酶表现出远缘相似性。LSD1的最适pH为6.0，最适温度为37℃。暴露于1 mM Hg2+、Ag3+和Mn2+会使LSD1葡聚糖酶活性基本丧失。LSD1对葡聚糖（100%）、可溶性淀粉（22%）和变聚糖（8%）表现出高水解活性。
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