Henzl M T, Zhao H, Saez C T
Biochemistry Department, University of Missouri at Columbia 65211, USA.
FEBS Lett. 1995 Nov 13;375(1-2):137-42. doi: 10.1016/0014-5793(95)01202-p.
The avian parvalbumin called CPV3 readily forms disulfide-linked oligomers. Sedimentation data presented herein reveal that CPV3 also undergoes noncovalent self-association. Interestingly, the noncovalent interaction is promoted by either Ca2+ or Mg2+, whereas covalent complex formation displays an absolute requirement for the Ca(2+)-bound protein. Apo-CPV3 exhibits an apparent sedimentation coefficient of 2.08 S at 20 degrees C, in 0.15 M NaCl, 0.025 M HEPES-NaOH, pH 7.4. This value increases to 2.85 S or 3.16 S with addition of 1.0 mM Ca2+ or 5.0 mM Mg2+, respectively. Least-squares analysis of sedimentation equilibrium data suggests that 100 microM apo-CPV3 is primarily a mixture of monomeric and dimeric forms. With the addition of Ca2+, the equilibrium becomes exclusively monomer-trimer, with negligible amounts of dimer. A comparable distribution is observed in the presence of Mg2+.
名为CPV3的禽源小清蛋白很容易形成二硫键连接的寡聚体。本文给出的沉降数据表明，CPV3也会发生非共价自缔合。有趣的是，Ca2+或Mg2+均可促进这种非共价相互作用，而共价复合物的形成则绝对需要结合了Ca(2+)的蛋白质。脱辅基CPV3在20℃、0.15 M NaCl、0.025 M HEPES - NaOH（pH 7.4）条件下的表观沉降系数为2.08 S。分别加入1.0 mM Ca2+或5.0 mM Mg2+后，该值分别增至2.85 S或3.16 S。沉降平衡数据的最小二乘法分析表明，100 microM脱辅基CPV3主要是单体和二聚体形式的混合物。加入Ca2+后，平衡完全变为单体 - 三聚体，二聚体的量可忽略不计。在Mg2+存在的情况下也观察到了类似的分布。
