Shimomura O, Shimomura A
Biochem J. 1984 Aug 1;221(3):907-10. doi: 10.1042/bj2210907.
The luminescence of aequorin, a useful tool for studying intracellular Ca2+, was recently found to be inhibited by the free EDTA and EGTA that are present in calcium buffers. In the present study we have examined the effect of the free forms of various chelators in the calibration of [Ca2+] with aequorin. Free EDTA and EGTA in low-ionic-strength solutions strongly inhibited the Ca2+-triggered luminescence of aequorin, causing large errors in the calibration of [Ca2+] (approx. 2 pCa units), whereas in solutions containing 150mM-KCl, errors were relatively small (0.2-0.3 pCa units). Citric acid in low-ionic-strength solutions and [(carbamoylmethyl)imino]diacetic acid in high-ionic-strength solutions showed no inhibition and did not cause detectable error in the calibration of [Ca2+], indicating that they are better chelators than EDTA and EGTA for use with aequorin.
水母发光蛋白是研究细胞内钙离子的一种有用工具,最近发现其发光会受到钙缓冲液中游离的乙二胺四乙酸(EDTA)和乙二醇双乙醚二胺四乙酸(EGTA)的抑制。在本研究中,我们检测了各种螯合剂的游离形式在用水母发光蛋白校准[Ca2+]时的影响。低离子强度溶液中的游离EDTA和EGTA强烈抑制水母发光蛋白的Ca2+触发发光,导致[Ca2+]校准中出现较大误差(约2个pCa单位),而在含有150mM-KCl的溶液中,误差相对较小(0.2-0.3个pCa单位)。低离子强度溶液中的柠檬酸和高离子强度溶液中的[(氨甲酰甲基)亚氨基]二乙酸未表现出抑制作用,且在[Ca2+]校准中未引起可检测到的误差,这表明它们是比EDTA和EGTA更适合与水母发光蛋白一起使用的螯合剂。