Boniface J J, Reichert L E
Department of Biochemistry, Albany Medical College, NY 12208.
Science. 1990 Jan 5;247(4938):61-4. doi: 10.1126/science.2104678.
It has been proposed that dithiol-disulfide interchange and oxidation-reduction reactions may play a role in hormone-induced receptor activation. Inspection of the sequences of the gonadotropic hormones revealed a homologous tetrapeptide (Cys-Gly-Pro-Cys) between the beta subunit of lutropin (LH) and the active site of thioredoxin (TD). The beta subunit of follitropin (FSH) has a similar sequence (Cys-Gly-Lys-Cys). Thioredoxin is a ubiquitous protein serving as an electron donor for ribonucleotide reductase, but it also exhibits disulfide isomerase activity. The catalytic activity of TD was assayed by its ability to reactivate reduced and denatured ribonuclease. In this assay, the purified ovine FSH and bovine LH preparations tested were approximately 60 and approximately 300 times, respectively, as active as TD on a molar basis. This heretofore unsuspected catalytic property of FSH and LH may be important in understanding their mechanism of receptor activation and signal transduction.
有人提出，二硫醇 - 二硫化物交换和氧化还原反应可能在激素诱导的受体激活中起作用。对促性腺激素序列的检查发现，促黄体生成素（LH）的β亚基与硫氧还蛋白（TD）的活性位点之间存在同源四肽（Cys - Gly - Pro - Cys）。促卵泡生成素（FSH）的β亚基有类似序列（Cys - Gly - Lys - Cys）。硫氧还蛋白是一种普遍存在的蛋白质，作为核糖核苷酸还原酶的电子供体，但它也表现出二硫键异构酶活性。通过其重新激活还原和变性核糖核酸酶的能力来测定TD的催化活性。在该测定中，所测试的纯化绵羊FSH和牛LH制剂在摩尔基础上的活性分别约为TD的60倍和约300倍。FSH和LH这种迄今为止未被怀疑的催化特性可能对理解它们的受体激活和信号转导机制很重要。
