Kinetics of antigenic peptide binding to the class II major histocompatibility molecule I-Ad.
Kinetics of antigenic peptide binding to the class II major histocompatibility molecule I-Ad.
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抗原肽与 II 类主要组织相容性分子 I-Ad 结合的动力学。
DOI：
10.1073/pnas.88.11.4661
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发表时间：
1991
影响因子：
11.1
通讯作者：
McConnell,HM
中科院分区：
文献类型：
--
作者：
Tampé,R;McConnell,HM
使用高效尺寸排阻色谱和荧光光谱，我们研究了荧光肽与去垢剂溶解的 I-Ad（小鼠主要组织相容性复合物的 II 类分子）反应的动力学。在 pH 7.0 和 37 摄氏度下，代表卵清蛋白氨基酸 323-339 [FOva-(323-339)Y] 的荧光素标记合成肽与 I-Ad 的结合半衰期为 32 小时，与 5-200 microM 范围内添加的荧光肽浓度无关。还进行了肽交换实验，发现FOva-(323-339)Y结合的半衰期等于德克萨斯红标记肽TROva-(323-339)Y解离的半衰期。这些实验表明，肽与II类主要组织相容性分子的缓慢结合可能受到预结合肽的缓慢解离的限制。然而，矛盾的是，这种动力学行为——肽浓度不敏感的反应，肽结合的半衰期大约等于解离的半衰期——可以用不止一种方式建模。涉及动力学中间体的模型特别有吸引力。 pH 5.0 时动力学显着不同。肽结合和解离的半衰期比 pH 7.0 时大约短 7 倍。此外，I-Ad α/β 异二聚体与 FOva-(323-339)Y 的复合物不稳定，解离成单独的 α 和 β 链，半衰期约为 7 小时。
Using high-performance size-exclusion chromatography and fluorescence spectroscopy, we investigated the kinetics of fluorescent peptide reactions with detergent-solubilized I-Ad, a class II molecule of the mouse major histocompatibility complex. At pH 7.0 and 37 degrees C the half-time for the binding of a fluorescein-labeled synthetic peptide representing ovalbumin amino acids 323-339 [FOva-(323-339)Y] to I-Ad was 32 hr, independent of added fluorescent peptide concentration in the range 5-200 microM. Peptide exchange experiments were also carried out, where it was found that the half-time of FOva-(323-339)Y binding was equal to the half-time of dissociation of the Texas Red-labeled peptide TROva-(323-339)Y. These experiments show that slow peptide binding to class II major histocompatibility molecules may be limited by the slow dissociation of prebound peptides. Paradoxically, however, this kinetic behavior--a peptide concentration-insensitive on-reaction with a half-time for peptide binding approximately equal to the half-time for dissociation--can be modeled in more than one way. Models involving a kinetic intermediate are particularly attractive. The kinetics were significantly different at pH 5.0. The half-times for peptide binding and dissociation were approximately 7 times shorter than at pH 7.0. In addition the complex of the I-Ad alpha/beta heterodimer with FOva-(323-339)Y was unstable and dissociated into separate alpha and beta chains with a half-time of approximately 7 hr.