l-Cysteine-synthesizing enzyme from 3-chloro-l-alanine resistant Bacillus sphaericus L-118
l-Cysteine-synthesizing enzyme from 3-chloro-l-alanine resistant Bacillus sphaericus L-118
复制标题
来自 3-氯-L-丙氨酸抗性球形芽孢杆菌 L-118 的 L-半胱氨酸合成酶
DOI：
10.1016/s0168-1656(84)90079-8
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发表时间：
1984
影响因子：
4.1
通讯作者：
H. Yamada
中科院分区：
文献类型：
--
作者：
G. S. Dhillon;T. Nagasawa;H. Yamada
从土壤中分离到一株对3-氯-L-丙氨酸具有抗性的细菌，经鉴定为球形芽孢杆菌L-118。该生物体的粗提物具有一种酶，该酶可在高浓度硫氢化钠存在下催化3-氯-l-丙氨酸的β-取代反应以形成l-半胱氨酸。半胱氨酸合成酶活性随培养基中3-氯-L-丙氨酸浓度的增加而增加。sphaericusL-118在不存在或存在3-氯-L-丙氨酸的情况下的酶活性，并且两种酶似乎是同质的。这两种酶具有相同的分子量（约68000）、相同的两个亚基分子量（约34000）、Km值（3-氯-1-丙氨酸为14.5mM，O-乙酰基-1-丝氨酸为7.8mM）、等电点（pH4.5）、底物特异性、免疫学性质和在DEAE-纤维素上的洗脱模式，并且被证实是相同的酶。此外，已经确定半胱氨酸合成酶是O-乙酰丝氨酸硫化氢解酶。
A bacterial strain that shows resistance to 3-chloro-L-alanine was isolated from the soil and identified asBacillus sphaericusL-118. The crude extract of this organism has an enzyme that can catalyze theβ-replacement reaction of 3-chloro-l-alanine in the presence of a high concentration of sodium hydrosulfide to forml-Cysteine. Thel-cysteine-synthesizing activity increased with an increase in 3-chloro-l-alanine in the medium.l-Cysteine-synthesizing enzymes were purified from the cells obtained by cultivatingB. sphaericusL-118 in the absence or presence of 3-chloro-l-alanine and both enzymes appeared to be homogeneous. Both enzymes exhibited the same molecular weight (about 68000), two subunits identical in molecular weight (about 34000),Kmvalues (14.5 mM for 3-chloro-l-alanine, 7.8 mM forO-acetyl-l-serine), isoelectric point (pH 4.5), substrate specificity, immunological properties and elution patterns on DEAE-cellulose, and were confirmed to be same enzyme. Further, it has been established that thel-cysteine-synthesizing enzyme wasO-acetylserine sulfhydrylase.