Baltz M L, De Beer F C, Feinstein A, Pepys M B
Biochim Biophys Acta. 1982 Feb 18;701(2):229-36. doi: 10.1016/0167-4838(82)90118-2.
Normal human serum or isolated human amyloid P component was ultracentrifuged on density gradients containing either 10 mM EDTA or different concentrations of Ca2+ between 0.15 and 2.15 mM. In the presence of Ca2+ concentrations of 1 mM or more human P component sedimented more rapidly than it did in the presence of lower Ca2+ levels or of EDTA. This phenomenon was due to Ca2+-dependent aggregation of P component molecules and did not require the presence of any other serum constituents. It was completely inhibited by incorporating a physiological concentration (40 mg/ml) of serum albumin in the gradients, suggesting that free ionized Ca2+ is required to promote aggregation of the P component. P component from the mouse and the plaice (Pleuronectes platessa L.), a marine teleost, did not undergo the same Ca2+-dependent aggregation as human P component. These observations resolve a discrepancy existing in the literature concerning the sedimentation rate of human P component in density gradient ultracentrifugation and shed new light on its behaviour with respect to Ca2+ which may be relevant to the deposition of P component in amyloidosis.
将正常人血清或分离出的人淀粉样蛋白P成分在含有10 mM乙二胺四乙酸（EDTA）或浓度在0.15至2.15 mM之间的不同浓度钙离子（Ca2+）的密度梯度上进行超速离心。在钙离子浓度为1 mM或更高时，人P成分的沉降速度比在较低钙离子水平或EDTA存在时更快。这种现象是由于P成分分子的钙离子依赖性聚集，并且不需要任何其他血清成分的存在。通过在梯度中加入生理浓度（40 mg/ml）的血清白蛋白，这种现象被完全抑制，这表明促进P成分聚集需要游离的离子钙。来自小鼠和鲽鱼（Pleuronectes platessa L.，一种海洋硬骨鱼）的P成分没有像人P成分那样发生相同的钙离子依赖性聚集。这些观察结果解决了文献中关于人P成分在密度梯度超速离心中沉降速率存在的差异，并为其与钙离子相关的行为提供了新的线索，这可能与淀粉样变性中P成分的沉积有关。
