Gahl W A, Tietze F, Butler J D, Schulman J D
Biochem J. 1985 Jun 15;228(3):545-50. doi: 10.1042/bj2280545.
Cystinotic lysosome-rich leucocyte granular fractions, loaded with [35S]cystine, were exposed to different cystine-depleting agents. During a 30 min incubation at 37 degrees C, untreated cystinotic granular fractions lost negligible [35S]cystine when corrected for lysosome rupture. Granular fractions exposed to 0.1 mM-cysteamine lost 64% of their initial cystine, and hexosaminidase activity was decreased by 10%. This was accompanied by the formation of high concentrations of [35S]cysteine-cysteamine mixed disulphide within the granular-fraction pellet, and, in the presence of N-ethylmaleimide, increasing amounts of [35S]cysteine-N-ethylmaleimide adduct outside the granular fraction. In separate experiments, [35S]cystine exited cystinotic leucocyte lysosomes at a negligible rate (half-times 199 and 293 min), but [35S]cysteine-cysteamine mixed disulphide exhibited substantial egress (half-times 66 and 88 min) and was recovered intact outside the granular-fraction pellet. We conclude that cysteamine depletes lysosomes of cystine by participating in a thiol-disulphide interchange reaction to produce cysteine and cysteine-cysteamine mixed disulphide, both of which traverse the cystinotic leucocyte lysosomal membrane.
将富含溶酶体的胱氨酸病白细胞颗粒组分装载上[35S]胱氨酸后，使其接触不同的胱氨酸消耗剂。在37℃孵育30分钟期间，经校正溶酶体破裂后，未经处理的胱氨酸病颗粒组分损失的[35S]胱氨酸可忽略不计。暴露于0.1 mM半胱胺的颗粒组分损失了其初始胱氨酸的64%，并且己糖胺酶活性降低了10%。这伴随着在颗粒组分沉淀中形成高浓度的[35S]半胱氨酸 - 半胱胺混合二硫化物，并且在存在N - 乙基马来酰亚胺的情况下，颗粒组分外部的[35S]半胱氨酸 - N - 乙基马来酰亚胺加合物的量增加。在单独的实验中，[35S]胱氨酸以可忽略不计的速率（半衰期分别为199和293分钟）从胱氨酸病白细胞溶酶体中逸出，但[35S]半胱氨酸 - 半胱胺混合二硫化物表现出大量逸出（半衰期分别为66和88分钟），并在颗粒组分沉淀外部完整回收。我们得出结论，半胱胺通过参与硫醇 - 二硫化物交换反应来消耗溶酶体中的胱氨酸，以产生半胱氨酸和半胱氨酸 - 半胱胺混合二硫化物，这两者都穿过胱氨酸病白细胞溶酶体膜。
