苦瓜提取物的抑菌活性研究

本文研究了苦瓜(MC)不同活性成分的抑菌活性.结果表明:苦瓜提取物对细菌的抑菌作用明显,但对霉菌、酵母菌的抑制效果不明显.苦瓜粗皂甙和苦瓜粗多糖的抑菌效果比纯品的好.苦瓜乙醇浸提物、苦瓜粗多糖、苦瓜多糖、苦瓜粗皂甙、苦瓜皂甙、苦瓜粗蛋白对藤黄八叠球菌的最低抑菌浓度(MIC)分别为50、100、5、100、2、20 mg/mL.苦瓜多糖、苦瓜皂甙和苦瓜蛋白是苦瓜抑菌活性功能成分.     

苦瓜核糖体失活蛋白的分离纯化及其抑制烟草花叶病毒活性

目的:探讨分离纯化苦瓜种子核糖体失活蛋白(RIP)的方法,并研究利用纯化后的RIP抑制烟草花叶病毒(TMV)的活性。方法:用盐溶液抽提总蛋白后,经30%～90%的(NH4)2SO4分级沉淀,制成粗提液。用CMSepharoseFastFlow离子交换层析结合SephadexG-75凝胶柱分离纯化RIP。结果与结论:经SDS-PAGE检测及RNAN-糖苷酶活性鉴定,确定最终得到的蛋白为苦瓜RIP;所纯化的RIP对感染黄瓜和番茄的TMV有明显的抑制作用,但RIP的浓度并不与其抑制TMV的活性呈正相关。     

聚丙烯酸分离纯化苦瓜种仁碱性蛋白的方法及影响因素

以苦瓜籽为材料,研究了聚丙烯酸分离纯化苦瓜种仁碱性蛋白的方法及影响因素。等电点沉淀试验表明,柠檬酸、盐酸分别调节苦瓜种仁粗提液pH至6.0、4.0时,各有14.62%和32.49%的苦瓜种仁蛋白被沉淀。醋酸的等电点沉淀作用呈现阶段性特点,pH6.0和4.0时分别有26.17%和38.72%的苦瓜种仁蛋白被沉淀。醋酸、盐酸和柠檬酸处理的1mL苦瓜种仁粗提液(pH4.0),1%PAA选择性沉淀碱性蛋白(等电点pI为8.65~9.30)的最佳用量分别为100μL、120μL和100μL。醋酸调节苦瓜种仁粗提液pH分别至5.0、4.0和3.0,等电点沉淀后的上清液用PAA沉淀碱性蛋白,当PAA(1%)用量为160μL/mL提取液时,pH5.0和3.0样液分别有33.77%和43.56%蛋白质被沉淀;当PAA用量为120μL/mL提取液时,pH4.0样液中30.83%蛋白质被沉淀。PAA-蛋白质复合物溶解于碱性溶液(pH>9.0),当溶液NaCl浓度为3.0%时,溶液蛋白质浓度最高。PAA选择性沉淀的苦瓜种仁碱性蛋白经SephadexG-75柱层析分离,分别在175min和300min出现主峰Ⅰ和Ⅱ。SDS-PAGE和IEF分析表明主峰Ⅰ的分子量约为30kD,pI值约为9.5,主峰Ⅱ的分子量约为10kD,pI值约为9.3。     

苦瓜的核糖体失活蛋白

核糖体失活蛋白是一类专一修饰核糖体的大亚基rRNA从而抑制蛋白质生物合成的蛋白毒素,可分为Ⅰ-型和Ⅱ-型两种类型。苦瓜中含有多种Ⅰ-型核糖体失活蛋白,如α-苦瓜素,β-苦瓜素和MAP30等,这些蛋白成分具有抗肿瘤、抗病毒和抗艾滋病等功能,因而近年来引起人们广泛的关注。对苦瓜核糖体失活蛋白的研究进展和应用前景进行了综述。     

苦瓜种子蛋白及其抑菌作用

SDS-PAGE分析表明,苦瓜种子含有多种蛋白组分,其中57kD和49kD蛋白可能由多个或多种亚基以二硫键结合形成。苦瓜种子蛋白对真菌和细菌有显著抑制效应。     

苦瓜水溶性粗多糖提取及降血糖功能研究

采用热水浸提法提取苦瓜水溶性多糖.通过正交试验优选浸提条件,确定苦瓜水溶性多糖最佳提取工艺条件为:即提取温度90℃,提取水料比为30:1,提取时间2 h.对苦瓜水溶性粗多糖的降血糖活性进行研究,结果表明:苦瓜水溶性多糖能够明显降低糖尿病小鼠的血糖,刘量500 mg/kg时,效果超出甲糖宁.     

聚丙烯酸分离纯化苦瓜种仁碱性蛋白的方法及影响因素

以苦瓜籽为材料,研究了聚丙烯酸分离纯化苦瓜种仁碱性蛋白的方法及影响因素。等电点沉淀试验表明,柠檬酸、盐酸分别调节苦瓜种仁粗提液pH至6.0、4.0时,各有14.62%和32.49%的苦瓜种仁蛋白被沉淀。醋酸的等电点沉淀作用呈现阶段性特点,pH 6.0和4.0时分别有26.17%和38.72%的苦瓜种仁蛋白被沉淀。醋酸、盐酸和柠檬酸处理的1mL苦瓜种仁粗提液（pH 4.0）,1%PAA选择性沉淀碱性蛋白（等电点pI为8.65～9.30）的最佳用量分别为100μL、120μL和100μL。醋酸调节苦瓜种仁粗提液pH分别至5.0、4.0和3.0,等电点沉淀后的上清液用PAA沉淀碱性蛋白,当PAA（1%）用量为160μL/mL提取液时,pH5.0和3.0样液分别有33.77%和43.56%蛋白质被沉淀;当PAA用量为120μL/mL提取液时,pH 4.0样液中30.83%蛋白质被沉淀。PAA-蛋白质复合物溶解于碱性溶液（pH＞9.0）,当溶液NaCl浓度为3.0%时,溶液蛋白质浓度最高。PAA选择性沉淀的苦瓜种仁碱性蛋白经Sephadex G-75柱层析分离,分别在175min和300min出现主峰Ⅰ和Ⅱ。SDS-PAGE和IEF分析表明主峰Ⅰ的分子量约为30kD,pI值约为9.5,主峰Ⅱ的分子量约为10kD,pI值约为9.3。     

苦瓜果实发育过程中的主要营养成分变化及种子生活力演进

为明确苦瓜的果实和种子的适宜采收时期,采用"翠中翠"苦瓜为研究对象,对苦瓜果实发育过程中的可溶性蛋白、总可溶性糖、维生素C的含量及种子生活力的变化进行动态监测。结果显示:(1)花后第14天至第26天,随着果实的迅速膨大,可溶性蛋白、总可溶性糖及维生素C含量也迅速增长;(2)种子干物质迅速积累,含水量迅速下降,种子生活力迅速提高,至花后第22天至第26天,种子生活力基本稳定。     

α-苦瓜素基因的克隆和原核表达

α-苦瓜素(Alpha-momorcharin)是一种多功能核糖体失活蛋白,具有抗肿瘤、抗HIV-1和抗菌活性,并同时具有免疫抑制活性.利用PCR(polymerase chain reaction)技术从苦瓜基因组中扩增出了成熟的α-苦瓜素蛋白基因,并亚克隆到表达载体pET28a( )上,然后分别在BL21(DE3) 和RosettaTM(DE3)pLysS中进行表达.结果表明只在RosettaTM(DE3)pLysS中,重组α-苦瓜素基因能成功地表达出33 kD大小的重组蛋白,而且在18℃和22℃的温度下,经IPTG诱导后,能成功地表达出大量可溶性重组蛋白.利用重组蛋白的N末端带有的6×His 标签,通过Ni-NTA柱纯化获得了α-苦瓜素重组蛋白.Western杂交实验表明,纯化后的重组蛋白可与鼠抗His-Tag单克隆抗体发生特异性反应.α-苦瓜素重组蛋白的获得为进一步系统研究和改造其功能与活性奠定了基础.     

苦瓜籽核糖体失活蛋白的理化性质及生物活性

采用硫酸铵分级分离,假配基亲和层析和ＳｅｐｈａｃｒｙｌＳ－１００分子筛层析等方法,从苦瓜籽中获得核糖体失活蛋白（ＲＩＰ）．经ＳＤＳ－ＰＡＧＥ、ＰＡＧＥ、ＩＥＦ和ＰＡＳ方法分析均表明为单一蛋白着色带或单一糖蛋白着色带．根据ＳＤＳ－ＰＡＧＥ和Ｓｅｐｈａｄｅｘ Ｇ－１５０分子筛层析结果计算其相对分子质量为３．０×１０４,经ＩＥＦ－ＰＡＧＥ结果计算其ｐＩ为８．９～９．０．对无细胞系统中蛋白质生物合成抑制活性明显,其ＩＣ５０为５．３×１０－ １０ ｍ ｏｌ／Ｌ左右．体外生物活性试验结果表明其对人肝癌细胞、Ｖｅｒｏ、ＳＰ２／０、３Ｔ３、Ｋｂ、Ｎａｖａｎａ 等肿瘤细胞株均表现有不同程度的抑制作用．而对完整细胞人胚肺二倍体细胞却毒性极小．因此,上述实验结果为该ＲＩＰ的进一步深入研究和有可能开发成免疫毒素的高效弹头药物提供了一定的工作基础．     

Investigation of the mechanism of temperature sensitivity of the electroreceptors of ampullae of lorenzini

In experiments on Black Sea skates (Raja clavata), the potential of the receptor epithelium of the ampullae of Lorenzini and spike activity of single nerve fibers connected to them were investigated during electrical and temperature stimulation. Usually the potential within the canal was between 0 and –2 mV, and the input resistance of the ampulla 250–400 k. Heating of the region of the receptor epithelium was accompanied by a negative wave of potential, an increase in input resistance, and inhibition of spike activity. With worsening of the animal's condition the transepithelial potential became positive (up to +10 mV) but the input resistance of the ampulla during stimulation with a positive current was nonlinear in some cases: a regenerative spike of positive polarity appeared in the channel. During heating, the spike response was sometimes reversed in sign. It is suggested that fluctuations of the transepithelial potential and spike responses to temperature stimulation reflect changes in the potential difference on the basal membrane of the receptor cells, which is described by a relationship of the Nernst's or Goldman's equation type.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. I. M. Sechenov, Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Pacific Institute of Oceanology, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Neirofiziologiya, Vol. 12, No. 1, pp. 67–74, January–February, 1980.     

Principles of organization and evolution of systems of regulation of functions

Evolution of living organisms is closely connected with evolution of structure of the system of regulations and its mechanisms. The functional ground of regulations is chemical signalization. As early as in unicellular organisms there is a set of signal mechanisms providing their life activity and orientation in space and time. Subsequent evolution of ways of chemical signalization followed the way of development of delivery pathways of chemical signal and development of mechanisms of its regulation. The mechanism of chemical regulation of the signal interaction is discussed by the example of the specialized system of transduction of signal from neuron to neuron, of effect of hormone on the epithelial cell and modulation of this effect. These mechanisms are considered as the most important ways of the fine and precise adaptation of chemical signalization underlying functioning of physiological systems and organs of the living organism