0.97 dethiobiotin合成酶的结构解析。
文章的细节
-
引用
复制到剪贴板 -
Sandalova T,施耐德G, Kack H, Lindqvist Y
0.97 dethiobiotin合成酶的结构解析。
Acta Crystallogr D Crystallogr杂志。1999年3月,55 (Pt 3): 610 - 24。
- PubMed ID
-
10089457 (在PubMed]
- 文摘
-
224 -残留蛋白的晶体结构从大肠杆菌dethiobiotin合成酶精制使用x射线衍射数据分辨率0.97在100 K。4143个蛋白质原子组成的模型,包括436年1859 H原子和溶剂网站,精制的最后R因子11.6%反射,并估计意思是标准的0.022原子位置的不确定性,源自反转阻塞矩阵。结构优化与一个完整的各向异性模型使用SHELX97原子位移参数。在整个精致立体化学的限制应用。在过去的周期,平面化的肽债券没有约束,导致平均ω值179.6度。蛋白质分析的各向异性区域的显示,它们形成四个集群的残留物。交替的侧链构象15残留物和六个主链原子的残留物从三个循环包括在模型中。C-HcO氢键的分析表明,这样的互动,而经常发生在防晒霜;总共16这样的氢键被发现。在中央β褶板13 C-HcO债券羰基O和Calpha H原子之间被发现。 Other interactions of this type involve main-chain-side-chain and side-chain-side-chain C-HcO bonds. The model includes 436 water sites, of which 233 molecules form the first hydration shell. Analysis of the protein-solvent interactions shows that about one third of the accessible surface of the enzyme is not covered by ordered solvent. No difference in propensity for ordered solvent close to hydrophilic or hydrophobic surface areas was found. The comparison of the 100 K structure with the structure of the enzyme determined at room temperature shows several regions with different conformation, including areas in the active site, suggesting that structural transitions can occur during flash freezing. This observation questions one of the basic assumptions in the analysis of enzymatic reaction mechanisms using cryocrystallography.