An extracellular poly(3-hydroxybutyrate) depolymerase from Alcaligenes faecalis.
An extracellular poly(3-hydroxybutyrate) depolymerase from Alcaligenes faecalis.
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来自粪产碱菌的胞外聚（3-羟基丁酸酯）解聚酶。
DOI：
10.1111/j.1432-1033.1982.tb05907.x
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
S. Masamune
中科院分区：
文献类型：
--
作者：
T. Tanio;T. Fukui;Y. Shirakura;Terumi Saito;K. Tomita;T. Kaiho;S. Masamune
从活性污泥中分离出的粪产碱杆菌 T1 菌株在以聚（3-羟基丁酸酯）作为唯一碳源的培养基中生长时，会分泌胞外聚（3-羟基丁酸酯）解聚酶。从培养基中纯化至电泳均质后，通过 Sephadex G-100 过滤测定，酶的分子量为 48 000，在十二烷基硫酸钠存在下，通过聚丙烯酰胺凝胶电泳测定，分子量为 50 000。酶反应的最适pH为7.5。纯化的酶解聚从Zoogloea ramigera 1-16-M纯化的聚(3-羟基丁酸酯)，但不攻击细菌天然的含有聚(3-羟基丁酸酯)的颗粒。聚(3-羟基丁酸酯)的Km值为13.3微克/ml（= 0.78微M，基于17000的估计平均分子量），D(--)-3-羟基丁酸三聚酯的Km值为5.4mM。对聚（3-羟基丁酸酯）、几种 D(--)-3-羟基丁酸低聚物酯和三聚酯甲酯的水解产物的分析表明，该酶从游离羟基末端水解这些底物，一次释放一个 D(--)-3-羟基丁酸酯二聚体单元。
A strain of Alcaligenes faecalis T1, which was isolated from activated sludge, excreted an extracellular poly(3-hydroxybutyrate) depolymerase as it grew in a medium containing poly(3-hydroxybutyrate) as the sole carbon source. The molecular weight of the enzyme, purified from the culture medium to electrophoretic homogeneity, was 48 000 as determined by Sephadex G-100 filtration, and 50 000 by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate. The pH optimum for the enzyme reaction was 7.5. The purified enzyme depolymerized poly(3-hydroxybutyrate) purified from Zoogloea ramigera 1-16-M, but did not attack the bacterial native poly(3-hydroxybutyrate)-containing granules. Km values were 13.3 micrograms/ml (= 0.78 microM, based on an estimated average molecular weight of 17 000) for poly(3-hydroxybutyrate) and 5.4 mM for the trimeric ester of D(--)-3-hydroxybutyric acid. Analysis of hydrolytic products of poly(3-hydroxybutyrate), several oligomeric esters of D(--)-3-hydroxybutyric acid, and the methyl ester of the trimeric ester indicated that the enzyme hydrolyzed these substrates from the free hydroxyl terminus, releasing D(--)-3-hydroxybutyrate dimer units one at a time.