Walker G E, Dunbar B, Hunter I S, Nimmo H G, Coggins J R
Division of Biochemistry and Molecular Biology, University of Glasgow, UK.
Microbiology (Reading). 1996 Aug;142 ( Pt 8):1973-82. doi: 10.1099/13500872-142-8-1973.
The tryptophan-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthases from Streptomyces coelicolor A3(2), Streptomyces rimosus and Neurospora crassa have been purified to homogeneity. All three enzymes have a subunit Mr of 54,000. The S. coelicolor DAHP synthase was physically and kinetically characterized and the N-terminal amino acid sequence was obtained. The N-terminal amino acid sequence could not be obtained for the enzymes from S. rimosus and N. crassa, their N-termini apparently being blocked. However, following proteolytic digestion, internal amino acid sequences were obtained from both enzymes. A comparison with the known DAHP synthase sequences indicated that these DAHP synthases are unrelated to other microbial DAHP synthase sequences but are similar to plant DAHP synthases. Up until now, two distinct classes of DAHP synthase have been described, one comprising exclusively enzymes from plants, the other restricted to enzymes from micro-organisms. These studies indicate that the class containing the plant DAHP synthases also contains enzymes from a microbial eukaryote and from several bacteria.
来自天蓝色链霉菌A3(2)、龟裂链霉菌和粗糙脉孢菌的色氨酸敏感型3-脱氧-D-阿拉伯庚酮糖-7-磷酸（DAHP）合酶已被纯化至同质。这三种酶的亚基分子量均为54,000。对天蓝色链霉菌DAHP合酶进行了物理和动力学表征，并获得了其N端氨基酸序列。对于龟裂链霉菌和粗糙脉孢菌的酶，无法获得N端氨基酸序列，它们的N端显然被封闭。然而，经过蛋白酶消化后，从这两种酶中都获得了内部氨基酸序列。与已知的DAHP合酶序列进行比较表明，这些DAHP合酶与其他微生物DAHP合酶序列无关，但与植物DAHP合酶相似。到目前为止，已经描述了两种不同类型的DAHP合酶，一类仅包含来自植物的酶，另一类仅限于来自微生物的酶。这些研究表明，包含植物DAHP合酶的类别中还包含来自微生物真核生物和几种细菌的酶。
