Smith F A, Lurie D J, Brady F, Danpure H J, Kensett M J, Osman S, Silvester D J, Waters S L
Int J Appl Radiat Isot. 1984 Jun;35(6):501-6. doi: 10.1016/0020-708x(84)90171-6.
Time integral and time-differential PAC measurements have been made over a wide temperature range in aqueous solutions of [111In]tropolonate and [111In]acetylacetonate. The quadrupole frequency in the latter is approximately 30% higher than that in the former and the molecular volumes derived from rotational correlation times show the expected differences. Apo-transferrin was separately added to the two 111In-chelates and the transfer of activity from chelate to transferrin followed as a function of relative molar concentrations. Very much larger molar ratios of transferrin to tropolone than of transferrin to acetylacetone were required before substantial transfer of 111In from chelate to transferrin took place. This difference in affinity for transferrin could be one significant factor in explaining the enhanced ability of [111In]tropolonate to label blood cells in the presence of plasma. The determination of PAC parameters in [111In]transferrin over a range of temperatures showed that the values of quadrupole frequency obtained depended on the number of binding sites assumed. For only one 111In site per molecule, the quadrupole frequency increases by over 50% as the temperature is reduced below the freezing point of the solution. If two 111In sites are assumed there appears to be a change in the percentage occupancy of the two sites on either side of the transition.
已在[111铟]托酚酮和[111铟]乙酰丙酮的水溶液中的较宽温度范围内进行了时间积分和时间微分的正电子湮没寿命谱（PAC）测量。后者的四极频率比前者高约30%，并且从旋转相关时间导出的分子体积显示出预期的差异。将脱铁转铁蛋白分别添加到两种111铟螯合物中，并跟踪活性从螯合物向转铁蛋白的转移，作为相对摩尔浓度的函数。在111铟从螯合物大量转移到转铁蛋白发生之前，转铁蛋白与托酚酮所需的摩尔比远大于转铁蛋白与乙酰丙酮所需的摩尔比。对转铁蛋白亲和力的这种差异可能是解释[111铟]托酚酮在血浆存在下标记血细胞能力增强的一个重要因素。在一系列温度下对[111铟]转铁蛋白中的PAC参数进行测定表明，获得的四极频率值取决于假定的结合位点数量。对于每个分子仅一个111铟位点，当温度降低到溶液冰点以下时，四极频率增加超过50%。如果假定有两个111铟位点，则在转变点两侧两个位点的占据百分比似乎会发生变化。
