Structural symmetry:: The three-dimensional structure of Haemophilus influenzae diaminopimelate epimerase
Structural symmetry:: The three-dimensional structure of Haemophilus influenzae diaminopimelate epimerase
复制标题
DOI：
10.1021/bi982138o
复制
发表时间：
1998-11-24
期刊：
影响因子：
2.9
通讯作者：
Blanchard, JS
中科院分区：
文献类型：
--
作者：
Cirilli, M;Zheng, RJ;Blanchard, JS
在C222(1)空间群（a = 102.1埃，b = 115.4埃，c = 66.3埃，α = β = γ = 90度）中克隆、表达、纯化和结晶流感嗜血杆菌二氨基酰亚胺酶。在常规R因子为19.0%（无R = 24.2%）的条件下，用单个Pt衍生物和se - met取代酶求解了2.7埃的三维结构。274个氨基酸的酶由两个结构同源结构域组成，每个结构域包含8个-链和2个-螺旋。二氨基苯甲酸酯外消旋酶是plp非依赖性氨基酸外消旋酶的代表，其结构尚未确定，有大量证据支持两个半胱氨酸残基作为催化酸和碱的作用。氨基末端结构域的Cys73与羧基末端结构域的Cys217位于二硫键界面，我们认为这两个半胱氨酸残基在还原活性酶中起着酸和碱的作用。
The Haemophilus influenzae diaminopimelate epimerase was cloned, expressed, purified, and crystallized in the C222(1) space group (a = 102.1 Angstrom, b = 115.4 Angstrom, c = 66.3 Angstrom, alpha = beta = gamma = 90 degrees). The three-dimensional structure was solved to 2.7 Angstrom using a single Pt derivative and the Se-Met-substituted enzyme to a conventional R factor of 19.0% (R-free = 24.2%). The 274 amino acid enzyme consists of two structurally homologous domains, each containing eight beta-strands and two alpha-helices. Diaminopimelate epimerase is a representative of the PLP-independent amino acid racemases, for which no structure has yet been determined and substantial evidence exists supporting the role of two cysteine residues as the catalytic acid and base. Cys73 of the amino terminal domain is found in disulfide linkage, at the domain interface, with Cys217 of the carboxy terminal domain, and we suggest that these two cysteine residues in the reduced, active enzyme function as the acid and base in the mechanism.