College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing, China.
J Microbiol Biotechnol. 2010 May;20(5):881-8. doi: 10.4014/jmb.0910.10038.
A solvent-tolerant bacterium strain MH6 was isolated by hydrophilic organic solvent DMSO enrichment in medium and identified as Serratia marcescens. The extracellular protease with novel organic-solvent-stable properties from strain MH6 was purified and characterized. The molecular weight of the purified protease was estimated to be 52 kDa on SDS-PAGE. The open reading frame (ORF) of the MH6 protease encoded 504 amino acids with 471 amino acid residues in the mature protease. Based on the inhibitory effects of EDTA and 1, 10-phenathroline, the MH6 protease was characterized as a metalloproteinase. The enzyme activity was increased in the presence of Ni2+, Mg2+, and Ca2+. The protease could also be activated by the nonionic surfactants Tween 80 (1.0%) and Triton X-100 (1.0%). The protease showed remarkable solvent stability in the presence of 50% (v/v) solutions of long-chain alkanes and long-chain alcohols. It was also fairly stable in the presence of 25% solutions of hydrophilic organic solvents. Due to its high stability in solvents and surfactants, the MH6 protease is an ideal candidate for applications in organic catalysis and other related fields.
一株耐有机溶剂的细菌 MH6 菌株通过在培养基中用亲水性有机溶剂 DMSO 进行富集分离，并被鉴定为粘质沙雷氏菌。从 MH6 菌株中纯化并表征了具有新型有机溶剂稳定性的胞外蛋白酶。SDS-PAGE 测定该蛋白酶的分子量约为 52 kDa。MH6 蛋白酶的开放阅读框（ORF）编码 504 个氨基酸，成熟蛋白酶含有 471 个氨基酸残基。根据 EDTA 和 1,10-菲咯啉的抑制作用，MH6 蛋白酶被鉴定为金属蛋白酶。该酶在存在 Ni2+、Mg2+和 Ca2+时活性增加。该蛋白酶还可以被非离子表面活性剂 Tween 80（1.0%）和 Triton X-100（1.0%）激活。该蛋白酶在存在 50%（v/v）长链烷烃和长链醇溶液中表现出显著的溶剂稳定性。在存在 25%亲水有机溶剂溶液中也相当稳定。由于其在溶剂和表面活性剂中的高稳定性，MH6 蛋白酶是有机催化和其他相关领域应用的理想候选者。
