MEMBRANE-ASSOCIATED REACTIONS IN UBIQUINONE BIOSYNTHESIS IN ESCHERICHIA-COLI - 3-OCTAPRENYL-4-HYDROXYBENZOATE CARBOXYLYASE
MEMBRANE-ASSOCIATED REACTIONS IN UBIQUINONE BIOSYNTHESIS IN ESCHERICHIA-COLI - 3-OCTAPRENYL-4-HYDROXYBENZOATE CARBOXYLYASE
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DOI：
10.1016/0005-2736(76)90407-7
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发表时间：
1976-01-01
期刊：
影响因子：
--
通讯作者：
GIBSON, F
中科院分区：
文献类型：
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作者：
LEPPIK, RA;YOUNG, IG;GIBSON, F
建立了3-八烯基-4-羟基苯甲酸酯羧解酶的灵敏定量测定方法。对该酶进行了部分纯化，并对其部分性质进行了测定。相当大比例的羧基裂解酶活性可以从用法国压榨机制备的细胞提取物的膜部分中分离出来。凝胶过滤表明，该酶的相对分子质量为.apprx。34万。为了获得最佳活性，羧解酶需要Mn2+、洗涤膜或磷脂提取物，以及一个未知的热稳定性因子(MW<；10,000)。二硫苏糖醇和甲醇对羧解酶有较强的刺激作用。将该羧解酶的性质与在体外研究的3种与泛醌生物合成有关的酶进行了比较。由于羧基裂解酶的底物是膜结合的，并且该酶受到磷脂的刺激，因此它在体内可能与细胞膜结合而正常发挥作用。
A sensitive and quantitative assay for 3-octaprenyl-4-hydroxybenzoate carboxy-lyase was developed. This enzyme which catalyses the 3rd reaction in E. coli ubiquinone biosynthesis, was partially purified and some of its properties determined. A considerable proportion of the carboxy-lyase activity could be separated from the membrane fraction in cell extracts prepared using a French press. Gel filtration showed the MW of the enzyme to be .apprx. 340,000. For optimal activity the carboxy-lyase required Mn2+, washed membranes or an extract of phospholipids, and an unidentified heat stable factor of MW < 10,000. The carboxy-lyase reaction was strongly stimulated by dithiothreitol and methanol. The properties of the carboxy-lyase are compared with 3 other enzymes concerned with ubiquinone biosynthesis in E. coli which were studied in vitro. Since the substrate of the carboxy-lyase is membrane-bound and the enzyme is stimulated by phospholipid, it may normally function in association with the cytoplasmic membrane in vivo.