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首页> 外文期刊>Journal of bacteriology >Purification and characterization of a Bacillus megaterium disulfide reductase specific for disulfides containing pantethine 4',4'-diphosphate.
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Purification and characterization of a Bacillus megaterium disulfide reductase specific for disulfides containing pantethine 4',4'-diphosphate.

机译：特大型芽孢杆菌二硫化物还原酶的纯化和表征，该二硫化物含有泛素4'，4“-二磷酸。

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摘要

An NADH-linked disulfide reductase specific for disulfides containing pantethine 4',4"-diphosphate moieties was purified 23,000-fold to homogeneity from spores of Bacillus megaterium. The enzyme had a native molecular weight of 122,000 with two apparently identical subunits, contained one molecule of flavin adenine dinucleotide per subunit, and was inhibited by the vicinal dithiol reagent arsenite. The enzyme was active only on disulfides containing pantethine 4',4"-diphosphate moieties, including pantethine 4',4"-diphosphate, oxidized coenzyme A, and coenzyme A in disulfide linkage to acyl carrier protein. However, the Km values for pantethine 4',4"-diphosphate and oxidized coenzyme A were 0.65 and 7.4 mM, respectively. The enzyme was at a low level in log-phase cells but increased up to 10-fold early in the stationary phase and had a similar specific activity in both the mother cell and the forespore compartment; the enzyme activity fell only slowly during spore germination and outgrowth. The enzyme was not detected in several eucaryotic sources and was present in at most a low level in a number of gram-negative bacteria. Surprisingly, the specific activity of this enzyme varied more than 200-fold in extracts from different Bacillus species, with values in B. subtilis being 5- to 6-fold lower and values in B. cereus and B. sphaericus being 8- and 35-fold higher, respectively, than the maximum value in B. megaterium. However, the high specific activity in B. sphaericus did not represent more enzyme protein than in B. megaterium. The possible function of this newly discovered enzyme is discussed.
机译：从巨大芽孢杆菌的孢子中纯化出23,000倍至同质的NADH联结的二硫化物还原酶，该二硫化物含有泛素4'，4“-二磷酸部分，该酶的天然分子量为122,000，带有两个明显相同的亚基，包含一个分子。黄素腺嘌呤二核苷酸每个亚基的含量，并被邻近的二硫醇试剂亚砷酸抑制。该酶仅对含有泛素4'，4“-二磷酸部分的二硫化物具有活性，包括泛素4'，4”-二磷酸，氧化的辅酶A和辅酶A与酰基载体蛋白二硫键连接，但是，泛酸4'，4“-二磷酸和氧化型辅酶A的Km值分别为0.65和7.4 mM。该酶在对数期细胞中处于较低水平，但在固定期早期增加至10倍，并且在母细胞和前孢子室中具有相似的比活性;在孢子萌发和生长过程中，酶的活性仅缓慢下降。在几种真核生物来源中未检测到该酶，并且在许多革兰氏阴性细菌中至多以低水平存在。令人惊讶地，该酶的比活性在来自不同芽孢杆菌属物种的提取物中变化超过200倍，其中枯草芽孢杆菌的值降低了5至6倍，蜡状芽孢杆菌和球形芽孢杆菌的值分别为8和35。分别比巨型芽孢杆菌中的最大值高两倍。但是，球形芽孢杆菌中的高比活性并不比巨大芽孢杆菌中代表更多的酶蛋白。讨论了这种新发现的酶的可能功能。

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