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在pH7.4,温度为25℃的条件下,用紫外吸收差光谱进行了Eu~(3+)对人血清脱铁转铁蛋白的滴定.结果表明Eu~(3+)与人血清脱铁转铁蛋白结合后其差光谱在245nm和296nm处出现吸收峰,在245nm处,Eu~(3+)-脱铁转铁蛋白配合物的摩尔吸光系数是(2.2±0.1)×10~4cm~(-1)·mol~(-1)·dm~3,Eu~(3+)可占据脱铁转铁蛋白的2个金属离子结合部位,Eu~(3+)优先占据脱铁转铁蛋白的C端结合部位,条件平衡常数是logK_c=8.42±0.12,logK_N=6.03±0.42.Eu~(3+)与R_E~(3+)(R_E=Nd,Sm,Gd和Tb)间的线性自由能关系表明,稀土离子占据脱铁转铁蛋白的C端结合部位时受离子大小的影响.
The titration of Eu ~ (3+) on human serum transferrin was carried out by UV-Absorption spectroscopy at a pH of 7.4 and at a temperature of 25 ° C. The results showed that Eu 3+ could be separated from human serum The absorption spectra of the conjugates of transferrin and ferricyanide at 245nm and 296nm showed that the molar absorptivities of Eu ~ (3 +) - aTRF at 245nm were (2.2 ± 0.1) × 10 ~ 4cm ~ (-1) · mol ~ (-1) · dm ~ 3, Eu ~ (3+) can occupy two metal ion binding sites of apo-transferrin, and Eu ~ (3+) The conditional equilibrium constants are logK_c = 8.42 ± 0.12 and logK_N = 6.03 ± 0.42.The linear freedom between Eu ~ (3+) and R_E ~ (3 +) (R_E = Nd, Sm, Gd and Tb) The relationship shows that the rare earth ions occupy the C-terminal binding site of the apotransferrin when influenced by the size of the ions.