Bridges K R, Hoffman K E
J Biol Chem. 1986 Oct 25;261(30):14273-7.
An important property of ascorbic acid is its ability to increase the availability of storage iron to chelators. To examine the mechanism of this effect, K562 cells were incubated with ascorbate, attaining an intracellular level of 1 nmol/10(7) cells. In contrast to the reductive mobilization of iron seen with isolated ferritin, ascorbate stabilized iron preincorporated into cellular ferritin. Biosynthetic labeling with [35S]methionine demonstrated that ascorbate also retarded the degradation of the ferritin protein shell. Ferritin is normally degraded in lysosomes. The lysosomal protease inhibitors leupeptin and chloroquine produced a qualitatively similar stabilization of ferritin. Ascorbate did not act as a general inhibitor of proteolysis, however, since it did not effect hemoglobin degradation in these cells. The stabilization of cellular ferritin by ascorbate was accompanied by an expansion of the pool of chelatable iron.
抗坏血酸的一个重要特性是它能够提高螯合剂对储存铁的利用率。为了研究这种作用的机制，将K562细胞与抗坏血酸盐一起孵育，使细胞内水平达到1 nmol/10(7)个细胞。与分离的铁蛋白所观察到的铁的还原性动员不同，抗坏血酸盐使预先掺入细胞铁蛋白的铁稳定下来。用[35S]甲硫氨酸进行生物合成标记表明，抗坏血酸盐还延缓了铁蛋白蛋白外壳的降解。铁蛋白通常在溶酶体中降解。溶酶体蛋白酶抑制剂亮抑酶肽和氯喹产生了性质上类似的铁蛋白稳定作用。然而，抗坏血酸并不是蛋白水解的一般抑制剂，因为它不影响这些细胞中血红蛋白的降解。抗坏血酸对细胞铁蛋白的稳定作用伴随着可螯合铁池的扩大。
