Identification of a conserved hydrophobic cluster in partially folded bovine beta-lactoglobulin at pH 2.
Identification of a conserved hydrophobic cluster in partially folded bovine beta-lactoglobulin at pH 2.
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pH 2 下部分折叠的牛 β-乳球蛋白中保守疏水簇的鉴定。
DOI：
10.1016/s1359-0278(97)00039-4
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
H. Molinari
中科院分区：
文献类型：
--
作者：
L. Ragona;F. Pusterla;L. Zetta;H. Monaco;H. Molinari
背景：核磁共振研究变性状态，完全展开和部分折叠，使深入了解构象和折叠过程中形成的相互作用。虽然部分折叠蛋白质的完整结构表征是一项非常困难的任务，但结构化子集（如疏水簇）的识别对于理解此类状态的结构组织具有价值。在这里，我们报告的NMR表征，在酸性条件下（pH 2），一个定义明确的疏水集群定位在核心的牛β-lactoglobulin.Results：存在的一个小的疏水集群存在于脂质运载蛋白家族已被评估的基础上获得的部分折叠的牛β-lactoglobulin. Results的结构对齐和NMR数据。已经预测了该簇的存在，鉴定了在该家族的大多数成员中高度保守的那些残基。在pH 2下进行的NMR研究显示，蛋白质具有非常稳定的β-核心以及无序区域，揭示了以Trp 19为中心的11个疏水残基的侧链中存在NOE，并指向蛋白质的内部。发现这种掩埋的簇在pH 2下是异常稳定的，不仅在室温下，而且在323 K下。此外，保守的疏水残基指向蛋白质的表面定义了一个疏水表面补丁位于链和helix.Conclusions之间的凹槽中检测到的掩埋簇最有可能在β-乳球蛋白的稳定性中起着重要作用。五个结构相关的蛋白质的分析表明，在这些结构中存在相同的扩展簇。我们建议，掩埋的集群可能代表的内部结合位点，以及疏水表面补丁参与第二个外部结合位点。
Background:NMR studies of denaturated states, both fully unfolded and partially folded, give insight into the conformations and interactions formed during folding. Although the complete structural characterization of partially folded proteins is a very difficult task, the identification of structured subsets, such as hydrophobic clusters, is of value in understanding the structural organization of such states. Here, we report the NMR characterization, in acidic conditions (pH 2), of a well-defined hydrophobic cluster localized in the core of bovineβ-lactoglobulin.Results:The existence of a small hydrophobic cluster present in the lipocalin protein family has been assessed on the basis of structural alignment and NMR data obtained for the partially folded bovineβ-lactoglobulin. The presence of the cluster had been predicted identifying those residues that are highly conserved in most members of the family. An NMR study conducted at pH 2, where the protein exhibits a very stableβ-core together with disordered regions, reveals the presence of NOEs among sidechains of 11 hydrophobic residues centered around Trp19 and pointing towards the interior of the protein. This buried cluster is found to be unusually stable at pH 2, not only at room temperature but also at 323K. Furthermore, conserved hydrophobic residues pointing towards the surface of the protein define a hydrophobic surface patch located in a groove between the strands and the helix.Conclusions:The detected buried cluster most likely plays an important role inβ-lactoglobulin stability. The analysis of five structurally related proteins reveals that the same extended cluster is present in these structures. We propose that the buried cluster may represent the internal binding site as well and that the hydrophobic surface patch is involved in a second external binding site.
影响因子：
2.9
作者：
ENGLANDER, SW;WAND, AJ
通讯作者：
WAND, AJ