Bandyopadhyay S, Ghosh S K
Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Calcutta, India.
J Protein Chem. 1990 Oct;9(5):603-11. doi: 10.1007/BF01025014.
Calmodulin has been purified in large quantities from goat (Capra hiscus) testis. The procedure includes heat treatment, hydrophobic interaction chromatography, and gel filtration. Goat testis calmodulin closely resembles other mammalian testis calmodulin studied so far. The protein has an extinction coefficient value (E1%1cm) of 2.09 at 280 nm, a Stokes radius of 23.2 A at 0.15 M KCl, and a frictional ratio of 1.38. Ca2+, and Tb3+ binding studies demonstrate that the protein has four Ca2(+)-binding sites with a Kd of 52.5 microM. Goat testis calmodulin shows close similarity to other calmodulins in the amino acid composition and in demonstrating an altered migration on SDS/PAGE upon Ca2+ binding. The protein also exhibits anomalously high values for molecular weight and Stokes radius as determined from the analytical gel chromatography and a change in its elution volume with the change of salt concentration in the eluant. These results have been discussed in view of the recently available knowledge from the crystallographic studies of rat testis calmodulin.
钙调蛋白已从山羊（Capra hiscus）睾丸中大量纯化出来。该过程包括热处理、疏水相互作用色谱法和凝胶过滤。山羊睾丸钙调蛋白与迄今为止研究的其他哺乳动物睾丸钙调蛋白非常相似。该蛋白质在280nm处的消光系数值（E1%1cm）为2.09，在0.15M KCl条件下的斯托克斯半径为23.2 Å，摩擦比为1.38。Ca2+和Tb3+结合研究表明，该蛋白质有四个Ca2(+)-结合位点，解离常数Kd为52.5 microM。山羊睾丸钙调蛋白在氨基酸组成上与其他钙调蛋白非常相似，并且在Ca2+结合后在SDS/PAGE上显示出迁移变化。通过分析凝胶色谱法测定，该蛋白质的分子量和斯托克斯半径也呈现出异常高的值，并且其洗脱体积会随着洗脱液中盐浓度的变化而改变。鉴于最近从大鼠睾丸钙调蛋白晶体学研究中获得的知识，对这些结果进行了讨论。
