Yamamoto K, Sekine T
J Biochem. 1983 Dec;94(6):2075-8. doi: 10.1093/oxfordjournals.jbchem.a134565.
To determine the spatial relationship between alkali light chain and actin in the actosubfragment-1 complex, we studied the cross-linking of actin and subfragment-1 with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. We found that (a) alkali light chain 1 was cross-linked to actin at two sites in the extrapeptide region, and (b) cross-linking of these two sites, especially the one which was very close to the NH2 terminal of the alkali light chain, to actin was inhibited drastically when the KCl concentration was increased from 0 to 100 mM. Since the inhibition of cross-linking with carbodiimide reagent means separation of amino and carboxyl groups in alkali light chain and actin, we suggest that this decrease in electrostatic attraction is the reason why subfragment-1 with alkali light chain 1 has higher affinity to actin than subfragment-1 with alkali light chain 2 at low ionic strength but has almost the same affinity at moderate ionic strength.
为了确定肌动蛋白亚片段-1复合物中碱性轻链与肌动蛋白之间的空间关系，我们研究了用1-乙基-3-(3-二甲基氨基丙基)碳二亚胺对肌动蛋白和亚片段-1进行交联的情况。我们发现：(a)碱性轻链1在肽外区域的两个位点与肌动蛋白发生交联；(b)当氯化钾浓度从0增加到100 mM时，这两个位点，尤其是非常靠近碱性轻链NH2末端的那个位点与肌动蛋白的交联被显著抑制。由于用碳二亚胺试剂抑制交联意味着碱性轻链和肌动蛋白中氨基和羧基的分离，我们认为这种静电吸引力的降低就是为什么在低离子强度下，含有碱性轻链1的亚片段-1比含有碱性轻链2的亚片段-1对肌动蛋白具有更高亲和力，但在中等离子强度下两者亲和力几乎相同的原因。
