The structure of [D-Hyi2,L-Hyi4]meso-valinomycin revealed by X-ray analysis.
The structure of [D-Hyi2,L-Hyi4]meso-valinomycin revealed by X-ray analysis.
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X 射线分析揭示了[D-Hyi2,L-Hyi4]内消旋缬氨霉素的结构。
DOI：
10.1002/bip.360310406
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发表时间：
1991
期刊：
影响因子：
2.9
通讯作者：
Duax,WL
中科院分区：
文献类型：
--
作者：
Pletnev,VZ;MikhailovaIYu;Ivanova,VT;Langs,DA;Grochulski,P;Duax,WL
直接X射线分析已用于确定[D-Hyi 2，L-Hyi 4]内消旋缬氨霉素{环[-D-瓦尔-D-Hyi-L-瓦尔-L-Hyi-（D-瓦尔-L-Hyi-L-瓦尔-D-Hyi）2-]，C60 H102 N6 O 18}的晶体结构，其从具有两个溶剂分子的丙酮中结晶。晶体为三方晶系，空间群为P32，晶胞参数a =B= 15.2085（8）°，c= 29.3250（9）°，晶胞内分子数Z = 3。在各向异性热运动近似中，考虑各向同性H原子的贡献，对C、N和O原子的原子坐标进行细化后的标准（R）和加权（Rw）可靠性因子分别为0.070和0.082。该分子为扭曲的手镯结构，由6个N <$H.<$O <$C4 → 1型分子内氢键稳定。侧链主要占据相对于分子圆柱轴的外部假轴位置。与中缬氨霉素相反，六个瓦尔羰基氧原子中只有四个向内形成分子的配位中心，残基D-Val 1和L-Val 3的羰基氧原子向外扭曲并远离分子中心。虽然类似物具有部分形成的离子结合中心，但由于D-Hyi 2和L-Hyi 4残基的疏水异丙基屏蔽了两侧的分子空腔，因此无法接近。
Direct x‐ray analysis has been used to determine the crystal structure of [D‐Hyi2,L‐Hyi4]meso‐valinomycin {cyclo[‐D‐Val‐D‐Hyi‐L‐Val‐L‐Hyi‐(D‐Val‐L‐Hyi‐L‐Val‐D‐Hyi)2‐], C60H102N6O18}, which crystallized from acetone with two solvent molecules. The crystals are trigonal, space group P32, number of molecules per unit cellZ= 3, cell parametersa=b= 15.2085 (8) Å,c= 29.3250 (9) Å, γ = 120°. The standard (R)and weighted (Rw) reliability factors after refinement of the atomic coordinates for C, N, and O atoms in the anisotropic thermal motion approximation, allowing for isotropic H atom contributions, were 0.070 and 0.082, respectively. The molecule adopts a distorted bracelet structure which is stabilized by six NH …︁ OC 4 → 1 type intramolecular hydrogen bonds. The side chains predominantly occupy external pseudoaxial positions relative to the cylindrical axis of the molecule. In contrast tomeso‐valinomycin, only four of the six Val carbonyl oxygen atoms are directed inwards to form a coordination centre for the molecule, and the carbonyl oxygen atoms of residuesD‐Val1andL‐Val3are twisted outward and point away from the centre of the molecule. Although the analogue has a partially formed ion‐binding center, it is inaccessible because the hydrophobic isopropyl groups of theD‐Hyi2andL‐Hyi4residues screen the molecular cavity on both sides.