Studies on Induction of Salivary Cysteine Proteinase Inhibitor by Isoproterenol

大鼠半胱氨酸蛋白酶抑制剂S(Rsc)，属于半胱氨酸蛋白酶抑制剂超家族2。(1)木瓜酶(KI：0.2nM)和无花果酶(Kl：0.2nM)抑制作用较强，菠萝酶和组织蛋白酶C有部分抑制作用。RSC竞争性抑制这些蛋白水解酶活性。但RSC对胰酶、激肽释放酶和胃酶无抑制作用。(2)当RsC被还原和S羧甲基化时，其对蛋白酶的抑制活性完全丧失。木瓜蛋白酶与RSC形成络合物的摩尔比为1：1。(3)在37ﾟC和热处理(100ﾟC，1 h)条件下，RSC的酶抑制活性在pH 1~12的范围内保持稳定。(4)半胱氨酸蛋白酶在微生物对人体组织的渗透中起着重要作用。用纸片扩散法检测了RSC对口腔细菌等17株细菌的抑菌活性。我们发现RSC对牙龈类杆菌具有抗菌活性，牙龈类杆菌是一种怀疑为牙周病病原体的口腔细菌(最低有效剂量：75杯/碟)。(5)用β-肾上腺素能激动剂异丙肾上腺素处理大鼠颌下腺，引起颌下腺肥大和增生，并诱导大量RSC。然而，对生物规律的反应并不了解。8周龄大鼠口腔中加入植物半胱氨酸蛋白酶木瓜酶后，颌下腺RSC水平显著升高。诱导RSC的程度和腺体增大的程度与木瓜酶的剂量和处理时间有关。我们测试了一种特定的蛋白水解酶。我们发现无花果半胱氨酸蛋白酶和胰腺丝氨酸蛋白酶具有相同的活性。我们认为，口服蛋白水解酶诱导颌下腺中的RSC是一种生物学反应，对防止外源性蛋白水解酶的损伤起作用。

Rat cystain S(RSC), a cysteine proteinase inhibitor belonging to family 2 of the cystatin superfamily. (1)Papain(Ki : O. l nM)and ficin(Kl : 0.2 nM)were inhibited strongly, and bromelain and cathepsin C partially. The proteinases were inhibited by RSC competitively. However, trypsin, kalllkrein and pepsin did not inhibit by RSC. (2)When RSC was reduced and S-carboxymethylated, the proteinases inhibitory activity was lost completly. Complex formation between papain and RSC was 1 : 1 molar ratio. (3)The proteinase inhibitory activity of RSC was stable to extremes of pH 1-12 for I hour at 37 ﾟC) and to heat treatment (100 ﾟC for 1 hour). (4)Cysteine proteinases are important in the penetration of human tissue by microorganism. Anti-bacteria activity of RSC was tested to seventeen strains including of oral bacteriaby disc diffusion analysis. We found that RSC have anti-bacterial activity against Bacteroides gingivalis, an oral bacterium suspected of being a pathogen of periodontal disease(minimum effective dose : 75 mug/disc). (5)Treatment of rats with the beta-adrenergic-agonist, isoproterenol, produces hypertrophy and hyperplasia of submandibular glands and induces a large quantity of RSC. However, biological rule of the responses did not understand. When papain, a cysteine proteinase of plant(papaya), was administered into the oral cavity of rats of 8 weeks age, a dramatic increase in the level of RSC in enlarged submandibular glands. The magnitude of induction of RSC and enlargement of the glands were correlated with the dose of papain and duration of the treatment. We tested to specify on the respence in kind of proteinase. We found that ficin, a cysteine proteinase of plant(Ficus), and trypsin, a serine proteinase of pancreas, had same activity. We proposed that induction of the RSC in the submandibular glands by oral administration of the proteinases is a biological response which plays a role in preventing injury exgeneous proteinases.