Degradation of a Novel Tripeptide, tert-Butoxycarbonyl-Tyr-Leu-Val-CH2Cl, with Inhibitory Effect on Human Leukocyte Elastase in Aqueous Solution and in Biological Fluids.
作者:Hiroyuki TOKUMITSU、Yoshinobu FUKUMORI、Yuko TSUDA、Yoshio OKADA、Fumiyo KASUYA、Kazuo IGARASHI、Miyoshi FUKUI
DOI:10.1248/cpb.45.1845
日期:——
The stability of tert-butoxycarbonyl-Tyr-Leu-Val-CH2Cl (YLV) with inhibitory effect of human leukocyte elastase was investigated in aqueous solution, α-chymotrypsin solution and biological media. In all cases studied here, the degradation was observed as a pseudo-first order reaction. The half-life for the degradation of YLV in an aqueous solution of pH 7.4 at 37°C was 35.9 h. YLV was most stable at about pH 3.8-5.8 and the effect of temperature was explained by the Arrhenius equation. The activation energies of the degradation in aqueous solutions at pH 2.0, 4.8, and 7.4 were 24.6, 22.1 and 23.4 kcal/mol, respectively. The degradation products in aqueous solution were analyzed by HPLC-MS and were estimated as Boc-Tyr-Leu-Val-CH2OH at pH 7.4 and H2N-Tyr-Leu-Val-CH2Cl at pH 2.0. In a bovine pancreas α-chymotrypsin solution at 37°C, the half-life and YLV was 15 min at 25.6 μg/ml of α-chymotrypsin solution. In the rat plasma, the half-life of YLV was 42.4 min (YLV 26.7 μg/ml plasma), and in rat liver, lung and spleen homogenates, the degradation rate constants of YLV were 37.6, 10.3 and 23.5 times larger than that in plasma solution, respectively (all fluids containing 5 mg protein/ml).YLV was less stable than nafarelin acetate, secretin, adrenocorticotropic hormone (ACTH) and gonadorelin in an aqueous solution of pH 7.4.
研究了在水溶液、α-糜蛋白酶溶液和生物介质中具有人类白细胞弹性蛋白酶抑制作用的叔丁氧羰基-Tyr-Leu-Val-CH2Cl(YLV)的稳定性。在本文研究的所有情况下,降解均为假一阶反应。YLV 在 pH 值为 7.4、温度为 37°C 的水溶液中的降解半衰期为 35.9 小时。YLV 在 pH 值为 3.8-5.8 左右时最为稳定,温度的影响可以用阿伦尼乌斯方程来解释。在 pH 值为 2.0、4.8 和 7.4 的水溶液中降解的活化能分别为 24.6、22.1 和 23.4 kcal/mol。水溶液中的降解产物经 HPLC-MS 分析,在 pH 值为 7.4 时为 Boc-Tyr-Leu-Val-CH2OH,在 pH 值为 2.0 时为 H2N-Tyr-Leu-Val-CH2Cl。在 37°C 的牛胰腺α-糜蛋白酶溶液中,当α-糜蛋白酶溶液的浓度为 25.6 μg/ml 时,YLV 的半衰期为 15 分钟。在大鼠血浆中,YLV 的半衰期为 42.4 分钟(YLV 26.7 μg/ml 血浆);在大鼠肝脏、肺脏和脾脏匀浆中,YLV 的降解速率常数分别为 37.6、10.3 和 23.5 倍。在 pH 值为 7.4 的水溶液中,YLV 的稳定性低于醋酸纳法瑞林、泌乳素、促肾上腺皮质激素(ACTH)和促性腺激素。