PROPERTIES OF A RAT SERUM-PROTEIN LABELED BY INJECTION OF SODIUM SELENITE
PROPERTIES OF A RAT SERUM-PROTEIN LABELED BY INJECTION OF SODIUM SELENITE
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DOI：
10.1016/0304-4165(77)90046-0
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发表时间：
1977-01-01
期刊：
影响因子：
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通讯作者：
HERRMAN, JL
中科院分区：
文献类型：
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作者：
HERRMAN, JL
注射低水平**图形**后标记的血清硒蛋白的性质。对摄入适量硒饲料的大鼠进行了研究。当注射后3h采集血清时，聚丙烯酰胺凝胶电泳法显示该标记优先结合到1个主要血清组分中。结合很强，这从以下事实证明：用0.60M氯化钠或0.50Mβ-巯基乙醇透析去除的标记很少；然而，用0.50M氢氧化钠透析去除了80%的75Se。十二烷基硫酸钠聚丙烯酰胺凝胶电泳法研究表明，在大多数情况下，亚基大小为49,000；当暴露在高浓度洗涤剂(2%)中时，约75Se与相对分子质量为25,000的蛋白质有关。天然硒蛋白在Sephadex G-150上洗脱于血清白蛋白之前，表明相对分子质量大于67,000。该硒蛋白在DEAE-Sephadex A-50上不与谷胱甘肽过氧化物酶结合。预先给予放线菌素D和放线菌亚胺后，~(75)Se在血清中的掺入量分别减少46%和70%，这与~(75)Se进入新合成蛋白质的假设一致。测得等电点为5.4，肝素存在时等电点降至3.2。用2M氯化钠处理不解离蛋白.cntdot.heparin复合体，而暴露在0.25Mβ-巯基乙醇中则导致60%的复合体解离。事实上，在大多数营养条件下被认为是正常水平的情况下，硒与血清蛋白1密切相关，这表明这种蛋白质可能在这种必要的微量营养素在体内的运输中发挥着重要作用。
Properties of a serum selenoprotein which was labeled after the injection of low levels of .**GRAPHIC**. to rats on a Se-adequate diet were investigated. When serum was collected 3 h after injection the label was incorporated preferentially into 1 major serum fraction as shown by polyacrylamide gel electrophoresis. Binding was strong, as demonstrated by the fact that very little label was removed by dialysis against 0.60 M NaCl or 0.50 M .beta.-mercaptoethanol; however, 80% of the 75Se was removed by dialysis against 0.50 M NaOH. MW studies by sodium dodecyl sulfate polyacrylamide gel electrophoresis gave a subunit size of 49,000 under most conditions; when exposed to high concentrations of the detergent (2%) some 75Se was associated with a protein having a MW of 25,000. The native selenoprotein eluted before serum albumin on Sephadex G-150 indicating a MW greater than 67,000. The selenoprotein did not coelute with glutathione peroxidase on DEAE-Sephadex A-50. The prior administration of actinomycin D and cycloheximide resulted in a reduction in incorporation of 75Se into serum by 46 and 70%, respectively, which is consistent with the hypothesis that 75Se is going into newly synthesized protein. The isoelectric point was determined to be 5.4; when heparin was present, the pI was lowered to 3.2. Treatment with 2 M NaCl did not dissociate the protein.cntdot.heparin complex, while exposure to 0.25 M .beta.-mercaptoethanol resulted in the dissociation of 60% of the complex. The fact that Se is so tightly associated with 1 serum protein when administered at levels that would be considered normal under most nutritional conditions suggests an important role for this protein, perhaps in the transport of this essential micronutrient throughout the body.