Sabbioni E, Marafante E
Chem Biol Interact. 1976 Sep;15(1):1-20. doi: 10.1016/0009-2797(76)90124-1.
In vivo experiments using 203Pb and radioactively labelled precursors such as [14C] arginine and [3H] tryptophan were performed to identify lead binding components in rat liver. The distribution of lead in 9 tissues and the intracellular distribution in liver and kidney was also investigated. Male rats were injected intravenously with 18 mug of 203Pb/rat and the 203Pb radioactivity was measured in whole tissues as well as in nuclei, mitochondria, lysosomes, microsomes and soluble fractions obtained by centrifugation of liver and kidney homogenates. The subcellular fractions from liver were purified and fractionated into macromolecular components by ultracentrifugation, gel filtration, ion exchange chromatography and solvent extraction. Nuclei were fractionated into membranes, chromatin proteins (histone and residual non-histone proteins) and DNA. Most of the lead was detected in the nuclear membrane fraction bound exclusively to membrane proteins and absent in phospholipids. The intranuclear lead was associated with histone fractions and other basic or very weakly acid proteins as indicated by the incorporation of [14C] arginine and [3H] tryptophan. Lead was present in the chromatographically purified DNA fraction but whether lead was really bound to the nucleic acid was not determined. Mitochondria were fractionated into heavy, soluble and light subfractions representing the inner membranes, the intramitochondrial matrix and the outer membranes respectively. These subfractions contained appreciable quantities of lead. No appreciable lead was present in lipids of the mitochondrial membranes. Significant quantities of lead were associated with the endoplasmic reticulum. Fractionation of microsomes into rough and smooth membranes showed that lead was almost exclusively bound to membranes of rough-surfaced microsomes associated with the heavy rough membrane subfraction. No significant lead was present in the free polysome subfraction or in lipids from the endoplasmic reticulum. More than one lead binding site was identified in the soluble fraction, the high molecular weight components representing the most important lead binding site.
利用²⁰³Pb以及放射性标记的前体物质，如[¹⁴C]精氨酸和[³H]色氨酸，进行了体内实验，以鉴定大鼠肝脏中的铅结合成分。同时还研究了铅在9种组织中的分布以及在肝脏和肾脏中的细胞内分布。给雄性大鼠静脉注射18μg/只的²⁰³Pb，然后测量全组织以及通过肝脏和肾脏匀浆离心获得的细胞核、线粒体、溶酶体、微粒体和可溶性组分中的²⁰³Pb放射性。对肝脏的亚细胞组分进行纯化，并通过超速离心、凝胶过滤、离子交换色谱和溶剂萃取将其分离为大分子成分。细胞核被分离为膜、染色质蛋白（组蛋白和残留的非组蛋白）和DNA。大部分铅在核膜组分中被检测到，且仅与膜蛋白结合，在磷脂中不存在。如[¹⁴C]精氨酸和[³H]色氨酸的掺入所示，核内铅与组蛋白组分以及其他碱性或极弱酸蛋白相关。铅存在于经色谱纯化的DNA组分中，但未确定铅是否真的与核酸结合。线粒体被分离为分别代表内膜、线粒体内基质和外膜的重、可溶性和轻亚组分。这些亚组分含有相当数量的铅。线粒体膜的脂质中不存在可观的铅。大量铅与内质网相关。将微粒体分离为粗面和滑面膜显示，铅几乎仅与与重的粗面膜亚组分相关的粗面微粒体膜结合。游离多核糖体亚组分或内质网脂质中不存在显著的铅。在可溶性组分中鉴定出不止一个铅结合位点，高分子量组分代表最重要的铅结合位点。
