Molecular Replacement Studies of Cucurmosin from Cucurbita Moschata:Structure Homology with Trichosanthin

High diffraction quality crystals of cucurmosin, a type I ribosome inactivating protein isolated from the sarcocarp of Cucurbita moschata (pumpkin), have been grown under newly optimised conditions. With in-house rotating anode X-ray source, these crystals diffract to 1.65 ?resolution which is much higher than that of the previously reported crystals that diffracted only to 3 ?resolution. The crystals belong to space group P212121 with cell parameters a = 41.5, b = 58.4 and c = 99.3 . Molecular replacement studies indicate that the cucurmosin structure is homologous to trichosanthin. The initial structural model has been obtained and the model fitting/ refinement is in progress.

南瓜蛋白对人胰腺癌SW1990细胞株的诱导凋亡作用

目的探讨南瓜蛋白体外对人胰腺癌SW1990细胞株的诱导凋亡作用。方法 MTT法检测南瓜蛋白对SW1990细胞的增殖抑制作用,透射电镜观察细胞凋亡表现,流式细胞仪检测其凋亡率,Western blot法检测caspase-3蛋白的表达。结果不同浓度(1.25、2.50、5.00、10.00、20.00、40.00及80.00μg/ml)南瓜蛋白作用不同时间(24、48及72 h)后,南瓜蛋白对胰腺癌细胞具有生长抑制作用,并呈时间和剂量依赖性(P<0.05)。40.00μg/ml南瓜蛋白作用72 h后,透射电镜下可见细胞出现明显的凋亡改变,并可见凋亡小体;不同浓度(0、2.50、10.00、40.00μg/ml)南瓜蛋白作用72 h后,细胞的凋亡率分别为(0.30±0.11)%、(18.93±1.06)%、(28.00±2.07)%及(49.93±3.25)%,随着药物浓度的升高,细胞的凋亡率逐渐增加,呈浓度依赖性(P<0.05);caspase-3蛋白表达随着药物浓度的升高逐渐增强,呈浓度依赖性(P<0.05)。结论南瓜蛋白可能通过上调caspase-3蛋白的表达诱导胰腺癌细胞凋亡。