Harvey S, Vrabel A, Smith S, Wieben E
Department of Biochemistry and Molecular Biology, Mayo Foundation, Rochester, Minnesota 55905, USA.
Biol Reprod. 1995 May;52(5):1059-65. doi: 10.1095/biolreprod52.5.1059.
The processing of secretory proteins in the guinea pig (GP) seminal vesicle epithelium (SVE) is altered by castration and restored by treatment of animals with androgens. To test the hypothesis that the changes in protein processing are due to changes in the activity of specific proteases, we examined the GPSVE for protease activities capable of cleaving a synthetic elastase substrate, succinyl-alanyl-alanyl-alanyl-p-nitroanilide (Suc(Ala)3pNA). We found that the GPSVE does contain a Suc(Ala)3pNA-cleaving activity that is sensitive to the serine protease inhibitor diisopropylfluorophosphate (DFP) and to the elastase inhibitor elastatinal. Furthermore, the amount of protease activity per milligram of SVE protein is reduced to about 50% of control levels by castration. The activity is completely restored within four days by treatment of castrated animals with androgens, but is not restored by treatment with estradiol, progesterone, or dexamethasone. Although the SVE enzyme did not yield a pattern of specific cleavage products when incubated with a secretory protein substrate in vitro, this enzyme activity was competitively inhibited by a peptide whose primary sequence included the cleavage site used by the processing machinery in vivo.
豚鼠（GP）精囊上皮（SVE）中分泌蛋白的加工过程会因去势而改变，并通过用雄激素治疗动物得以恢复。为了检验蛋白质加工变化是由于特定蛋白酶活性改变这一假设，我们检测了GP SVE中能够切割合成弹性蛋白酶底物琥珀酰 - 丙氨酰 - 丙氨酰 - 丙氨酰 - 对硝基苯胺（Suc(Ala)3pNA）的蛋白酶活性。我们发现GP SVE确实含有一种对丝氨酸蛋白酶抑制剂二异丙基氟磷酸酯（DFP）和弹性蛋白酶抑制剂弹性蛋白酶抑制剂敏感的Suc(Ala)3pNA切割活性。此外，每毫克SVE蛋白的蛋白酶活性量通过去势降低至对照水平的约50％。通过用雄激素治疗去势动物，该活性在四天内完全恢复，但用雌二醇、孕酮或地塞米松治疗则不能恢复。尽管SVE酶在体外与分泌蛋白底物孵育时未产生特定切割产物的模式，但该酶活性受到一种肽的竞争性抑制，该肽的一级序列包括体内加工机制所使用的切割位点。
