Chemistry Department, University of Nebraska, 704 Hamilton Hall, Lincoln, NE 68588-0304, USA.
J Pharm Biomed Anal. 2011 Jan 25;54(2):426-32. doi: 10.1016/j.jpba.2010.09.003. Epub 2010 Sep 15.
The presence of elevated levels of glucose in blood during diabetes can lead to the non-enzymatic glycation of serum proteins such as human serum albumin (HSA). This study examined the changes that occur in binding of the sulfonylurea drug tolbutamide to HSA as the level of glycation for this protein was increased. High-performance affinity chromatography was used in this work along with columns containing various preparations of in vitro glycated HSA. It was found in frontal analysis experiments that the binding of tolbutamide with all of the tested preparations of glycated HSA could be described by a two-site model involving both strong and weak affinity interactions. The association equilibrium constants (K(a)) for tolbutamide at its high affinity sites on glycated HSA were in the range of 0.8-1.2 x 10⁵ M⁻¹ and increased by 1.4-fold in going from normal HSA to mildly glycated HSA. It was found through competition studies that tolbutamide was binding at both Sudlow sites I and II on the glycated HSA, in agreement with previous studies. The K(a) for tolbutamide at Sudlow site II increased by 1.1- to 1.4-fold in going from normal HSA to glycated HSA. At Sudlow site I, the K(a) for tolbutamide increased by 1.2- to 1.3-fold in going from normal HSA to the glycated HSA samples. This information demonstrates the effects that glycation can have on drug interactions on HSA and should provide a better quantitative understanding of how the protein binding of tolbutamide in serum may be affected for individuals with diabetes.
糖尿病患者血液中葡萄糖水平升高会导致血清蛋白（如人血清白蛋白，HSA）的非酶糖基化。本研究考察了随着 HSA 糖基化水平的增加，磺酰脲类药物甲苯磺丁脲与 HSA 结合所发生的变化。这项工作使用了高效亲和色谱法，以及含有各种体外糖基化 HSA 制剂的柱子。在前沿分析实验中发现，所有测试的糖基化 HSA 制剂与甲苯磺丁脲的结合都可以用涉及强和弱亲和力相互作用的双位点模型来描述。甲苯磺丁脲在糖基化 HSA 高亲和力部位的缔合平衡常数（K(a)）在 0.8-1.2×10⁵ M⁻¹范围内，从正常 HSA 到轻度糖基化 HSA 增加了 1.4 倍。通过竞争研究发现，甲苯磺丁脲结合在糖基化 HSA 的 Sudlow 位点 I 和 II 上，与先前的研究一致。甲苯磺丁脲在 Sudlow 位点 II 的 K(a)从正常 HSA 到糖基化 HSA 增加了 1.1-1.4 倍。在 Sudlow 位点 I，甲苯磺丁脲的 K(a)从正常 HSA 到糖基化 HSA 样品增加了 1.2-1.3 倍。这些信息表明了糖基化对 HSA 上药物相互作用的影响，应该为更好地定量理解糖尿病患者血清中甲苯磺丁脲的蛋白质结合可能受到的影响提供依据。
