PLASMODIUM-FALCIPARUM - INHIBITORS OF LYSOSOMAL CYSTEINE PROTEINASES INHIBIT A TROPHOZOITE PROTEINASE AND BLOCK PARASITE DEVELOPMENT
PLASMODIUM-FALCIPARUM - INHIBITORS OF LYSOSOMAL CYSTEINE PROTEINASES INHIBIT A TROPHOZOITE PROTEINASE AND BLOCK PARASITE DEVELOPMENT
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DOI：
10.1016/0166-6851(89)90120-5
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发表时间：
1989-06-15
影响因子：
1.5
通讯作者：
LEECH, JH
中科院分区：
文献类型：
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作者：
ROSENTHAL, PJ;MCKERROW, JH;LEECH, JH
恶性疟原虫的滋养体通过在酸性食物泡中降解宿主红细胞血红蛋白来获得用于蛋白质合成的游离氨基酸。我们以前报道过亮抑酶素和L-反式-环氧琥珀酰-亮氨酰氨基（4-胍基）丁烷（E-64），两种半胱氨酸类蛋白酶的抑制剂，阻断了滋养体食物泡中的血红蛋白降解，我们确定了一种28-kDa的滋养体半胱氨酸蛋白酶作为潜在的食物泡血红蛋白酶。我们没有报道滋养体半胱氨酸蛋白酶的生化性质与溶酶体半胱氨酸蛋白酶组织蛋白酶B和组织蛋白酶L的相似。滋养体蛋白酶的最适pH值为5.5-6.0，接近两种溶酶体蛋白酶的最适pH值，并且它被组织蛋白酶B和组织蛋白酶L的高度特异性的重氮甲基酮和氟甲基酮抑制剂有效地抑制。滋养体蛋白酶和组织蛋白酶L一样，更喜欢精氨酸与疏水氨基酸相邻的肽底物。微摩尔浓度的氟甲基酮抑制剂Z-Phe-Ala-CH 2F阻断了滋养体食物泡中血红蛋白的降解，并阻止了寄生虫的繁殖。在以前的研究中，高浓度的抑制剂对小鼠没有毒性。我们的研究结果提供了额外的证据表明，28 kDa的滋养体嘌呤酶是一种食物空泡血红蛋白酶，并建议酶的特异性抑制剂可能具有潜在的抗疟疾药物。
Trophozoites of Plasmodium falciparum obtain free amino acids for protein synthesis by degrading host erythrocyte hemoglobin in an acidic food vacuole. We previously reported that leupeptin and L-trans-epoxysuccinyl-leucylamido(4-guanidino)butane (E-64), two inhibitors of the cysteine class of proteinases, blocked hemoglobin degradation in the trophozoite food vacuole, and we identified a 28-kDa trophozoite cysteine proteinase as a potential food vacuole hemoglobinase. We no report that the biochemical properties of the trophozoite cysteine proteinase closely resembled those of the lysosomal cysteine proteinases cathepsin B and cathepsin L. The trophozoite proteinase had a pH optimum of 5.5-6.0, near that of both lysosomal proteinases, and it was efficiently inhibited by highly specific diazomethylketon and fluoromethylketone inhibitors of cathepsin B and cathepsin L. the trophozoite proteinase preferred peptide substrates with arginine adjacent to hydrophobic amino acids, as does cathepsin L. Micromolar concentrations of the fluromethylketone inhibitor Z-Phe-Ala-CH2F blocked the degradation of hemoglobin in the trophozoite food vacuole and prevented parasite multiplication. In previous studies much higher concentration of the inhibitor were not toxic for mice. Our results provide additional evidence that the 28-kDa trophozoite priteinase is a food vacuole hemoglobinase and suggest that specific inhibitors of the enzyme may have potential as antimalirial drugs.