Electrokinetic properties of the sarcoplasmic reticulum membrane obtained from reconstitution studies.
Electrokinetic properties of the sarcoplasmic reticulum membrane obtained from reconstitution studies.
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从重建研究中获得的肌浆网膜的动电特性。
DOI：
10.1007/s002329900479
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Wang,S
中科院分区：
文献类型：
--
作者：
Smejtek,P;Mense,M;Word,R;Wang,S
用不带电荷的脂质以及带电荷和不带电荷的脂质的两种混合物重构的SR囊泡的电泳迁移率数据（Brethes，D.，Dulon，D.，Johannin，G.，Arrio，B.，Gulik-Krzywicki，T.，Chevallier，J. 1986年。Study of electrokinetic properties of reconstituted sarcoplasmic reticulum vesicles. Arch.Biochem.Bioprotein.246：355 - 356）根据膜-水界面的四种模型进行分析：（I）光滑的带负电荷的表面;（II）覆盖有电中性表面摩擦层的脂双层的带负电荷的表面;（III）电中性脂质双层，其在双层表面上方一定距离处覆盖有含有负电荷片的中性摩擦层;（IV）覆盖有均匀带电摩擦层的电中性脂质双层。从Poisson-Boltzmann和Navier-Stokes方程的数值积分预测电泳迁移率。实验结果仅与基于模型III的预测一致，其中双层上方约4 nm的带电片和约10 nm厚的摩擦层。假设SR膜上的电荷完全来自于Ca~（++）-ATP酶泵上的电荷，SR和重构SR囊泡的迁移率数据与12个电子电荷/ATP酶一致。该值与从氨基酸序列（-11e）估算的ATP酶胞质部分的净电荷值相当。带电片层的位置表明ATP酶上的电荷集中在胞质部分的中间。SR的摩擦层也属于Ca~（++）-ATP酶的胞质部分。该层的特征在于流体动力学屏蔽长度为1.1 nm。其厚度与Ca ++-ATP酶的细胞质部分的高度相当。
Electrophoretic mobility data of SR vesicles reconstituted with uncharged and two mixtures of charged and uncharged lipids (Brethes, D., Dulon, D., Johannin, G., Arrio, B., Gulik-Krzywicki, T., Chevallier, J. 1986. Study of the electrokinetic properties of reconstituted sarcoplasmic reticulum vesicles.Arch. Biochem. Biophys.246:355–356) were analyzed in terms of four models of the membrane-water interface: (I) a smooth, negatively charged surface; (II) a negatively charged surface of lipid bilayer covered with an electrically neutral surface frictional layer; (III) an electrically neutral lipid bilayer covered with a neutral frictional layer containing a sheet of negative charge at some distance above the surface of the bilayer; (IV) an electrically neutral lipid bilayer covered with a homogeneously charged frictional layer. The electrophoretic mobility was predicted from the numerical integration of Poisson-Boltzmann and Navier-Stokes equations. Experimental results were consistent only with predictions based on Model-III with charged sheet about 4 nm above the bilayer and frictional layer about 10 nm thick. Assuming that the charge of the SR membrane is solely due to that on Ca++-ATPase pumps, the dominant SR protein, the mobility data of SR and reconstituted SR vesicles are consistent with 12 electron charges/ATPase. This value compares well to the net charge of the cytoplasmic portion ofATPaseestimated from the amino acid sequence (-11e). The position of the charged sheet suggests that the charge on theATPaseis concentrated in the middle of the cytoplasmic portion. The frictional layer of SR can be also assigned to the cytoplasmic portion of Ca++-ATPase. The layer has been characterized with hydrodynamic shielding length of 1.1 nm. Its thickness is comparable to the height of the cytoplasmic portion of Ca++-ATPase.