Structural and Thermodynamic Studies on Protein G

蛋白 G 的结构和热力学研究

• 批准号: 9219309
• 负责人: John Orban
• 金额: $ 63.5万
• 依托单位: University of Maryland Biotechnology Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-03-01 至 1998-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9219309&HistoricalAwards=false
• 关键词: Structural; Thermodynamic; Studies; Protein

Protein G is a multi-domain component of the cell wall of some Streptococcal species and binds to all subclasses of human immunoglobulin G (IgG) by the constant Fc region. The IgG binding function of Streptococcal Protein G is contained in a globular domain of 56 amino acids designated GB. The objectives of this proposal are 1) to determine the tertiary structure of GB and relevant mutants using NMR spectroscopy; 2) to use this domain as a model to study protein folding and stability using NMR, microcalorimetry, CD, fluorescence spectroscopy and site- directed mutagenesis; and 3) to study the basic mechanisms of molecular recognition involved in the high affinity interaction of GB with the heavy-chain, constant region (Fc) of IgG using the above methods. The long term objective is to better understand the function of this class of Fc receptor proteins and engineer new classes of Fc receptor proteins. %%% GB is an ideal protein to probe the relationship of amino acid sequence to structure and stability. It is on the lower limit in size for a stable unique protein structure. Furthermore it achieves its stability without disulfide bonds or tight ligand binding. Its small size permits the application of numerous biophysical techniques to study the folding and stability, in particular NMR methods. Little information is yet available concerning the specific nature of the binding interaction of GB with Fc or the mechanism of its class selectivity. Because Protein G is class specific in its binding to IgG and binds to the portion of the immunoglobulin that defines its class, we believe that our proposed studies will not only help elucidate the mechanism of recognition but also permit the engineering of Fc receptors with new class selectivities. Fc receptors with new properties will have numerous medical and biotechnological applications.

G 蛋白是某些链球菌属细胞壁的多结构域成分，通过恒定 Fc 区与人免疫球蛋白 G (IgG) 的所有亚类结合。 链球菌 G 蛋白的 IgG 结合功能包含在一个由 56 个氨基酸组成的球状结构域中，称为 GB。 该提案的目标是 1) 使用核磁共振波谱确定 GB 和相关突变体的三级结构； 2) 使用该结构域作为模型，利用 NMR、微量热法、CD、荧光光谱和定点诱变研究蛋白质折叠和稳定性； 3)利用上述方法研究GB与IgG重链恒定区(Fc)高亲和力相互作用的分子识别基本机制。 长期目标是更好地了解此类 Fc 受体蛋白的功能并设计新类 Fc 受体蛋白。 %%% GB 是探索氨基酸序列与结构和稳定性关系的理想蛋白质。 它处于稳定的独特蛋白质结构的大小下限。 此外，它无需二硫键或紧密的配体结合即可实现稳定性。 它的小尺寸允许应用多种生物物理技术来研究折叠和稳定性，特别是核磁共振方法。 关于 GB 与 Fc 结合相互作用的具体性质或其类别选择性机制的信息还很少。 由于蛋白 G 与 IgG 的结合具有类别特异性，并且与定义其类别的免疫球蛋白部分结合，因此我们相信我们提出的研究不仅有助于阐明识别机制，而且还允许对具有新类别选择性的 Fc 受体进行工程改造。 具有新特性的Fc受体将有许多医学和生物技术应用。