Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China.
Nanotechnology. 2011 Jun 17;22(24):245105. doi: 10.1088/0957-4484/22/24/245105. Epub 2011 May 4.
Haptoglobin (Hp) is an acute phase protein that binds free hemoglobin (Hb), preventing Hb-induced oxidative damage in the vascular system. There are three phenotypes in human Hp, whose heterogeneous polymorphic structures and varying concentrations in plasma have been attributed to the cause of diseases and outcome of clinical treatments. Different phenotypes of Hp may be composed of the same subunits but different copy numbers, rendering their determination difficult by a single procedure. In this study, we have developed a simple, fast, reliable and sensitive method, using label-free nanogold-modified bioprobes coupled with self-development electrochemical impedance spectroscopy (EIS). By this method, probe surface charge transfer resistance is detected. The relative charge transfer resistance ratios for Hp 1-1, Hp 2-1 and Hp 2-2 were characterized. We were able to determine protein size difference within 3 nm, and the linear region of the calibration curve for Hp levels in the range of 90 pg ml(-1) and 90 µg ml(-1) (∼1 fM to 1 pM). We surmise that similar approaches can be used to investigate protein polymorphism and altered protein-protein interaction associated with diseases.
触珠蛋白（Hp）是一种急性时相蛋白，可结合游离血红蛋白（Hb），防止 Hb 引起血管系统的氧化损伤。人类 Hp 有三种表型，其异质多态结构和血浆中的浓度变化归因于疾病的病因和临床治疗的结果。不同表型的 Hp 可能由相同的亚基组成，但拷贝数不同，因此单一程序很难确定其组成。在本研究中，我们开发了一种简单、快速、可靠和灵敏的方法，使用无标记纳米金修饰的生物探针结合自发展电化学阻抗谱（EIS）。通过该方法，检测探针表面电荷转移电阻。对 Hp 1-1、Hp 2-1 和 Hp 2-2 的相对电荷转移电阻比进行了特征分析。我们能够在 3nm 内确定蛋白质大小差异，并且在 90pg/ml（~1fM 到 1pM）范围内的 Hp 水平的校准曲线的线性区域。我们推测，类似的方法可以用于研究与疾病相关的蛋白质多态性和改变的蛋白质-蛋白质相互作用。
