五步蛇蛇毒类凝血酶N端的部分氨基酸序列

从五步蛇蛇毒中纯化得到的类凝血酶,在SDS-PAGE及IEF均为一条带,且分子质量约38 ku,等电点约为4.0。测定该酶N端15个氨基酸的序列是VIGGVECDINEHRFL,与其他的蛇毒类凝血酶有高度同源性。     

清栓酶治愈10例急性肺栓塞报告

我们应用清栓酶对10例急性肺栓塞患者进行治疗观察,收到出人意料的临床效果,未发现明显的不良反应,提示该药溶栓、抗凝、止痛、止血等效果迅速、显著,确实。该药药源丰富,作用优于尿激酶,使用简便、安全,是治疗急性肺血栓病的一种颇有前途的新药。     

Crystal structure determination of basic phospholipase A_2 from venom of Agkistrodon halys pallas by molecular replacement method

Basic phospholipase A2 (BPLA2) from the venom of Agkistrodon halys pallas has a strong ability to hemolyze erythrocytes. The asymmetrical unit of P212121 crystal of BPLA2 contains two molecules. Self-rotation function was used to study the orientation relationship of these two molecules. Cross-rotation and translation functions were then used to determine the orientations and positions of the two molecules in the unit cell. The model building and preliminary structure refinement were carried out. The result shows that the two molecules in the asymmetrical unit of orthorhombic crystal are related by a non-crystallographic 2-fold symmetry axis.     

浙江蝮蛇蛇毒蛋白水解酶(蛋白酶a)的酶学性质及生物学活性研究

应用离子交换及凝胶柱层析,从浙江蝮蛇(Agkistrodon halys Pallas)蛇毒中分离纯化出一种具有酪蛋白水解活性的蛋白酶a。经研究表明,以酪蛋白为底物,该蛋白酶a作用的最适pH值为9.5,最适温度为45℃,Km值为1.33×10~(-5)mol/L,酶活性受EDTA抑制。蛋白酶a不水解TAME,BAEE等精氨酸脂。实验表明,蛋白酶a具有纤维蛋白溶解作用而无出血毒性,EDTA和半胱氨酸可抑制其纤溶活性。     

浙江产蝮蛇(Agkistrodon halys Pallas)蛇毒抗凝血活酶组份抗凝机理的研究

应用三次离子交换柱层析和一次凝胶过滤从浙江产蝮蛇毒中分离纯化了抗凝血活酶组份。测定出该组份由119个氨基酸残基组成,分子量为15,000道尔顿,等电点为9.4,N—末端为组氨酸。 纯化的抗凝血活酶组份在体外对血浆重钙化时间有显著影响,但不延长血浆凝血酶原时间和凝血酶时间,对纤维蛋白也无溶解作用,极低浓度（0.5微克/毫升）的抗凝组份就能抑制血液凝血活酶的生成。家兔静脉注射抗凝血活酶组份后十分钟,全血凝固时间和血浆重钙化时间均明显延长,但血浆凝血酶原时间、纤维蛋白含量和全血凝块溶解时间却不受影响。 蝮蛇毒抗凝血活酶组份具有磷脂酶A_2活性,但血浆中磷脂的水解似乎并不是血浆凝固延迟的主要原因,很可能是抗凝血活酶组份能够同血浆中凝血活酶组份（磷脂部份）可逆地结合,从而干扰了凝血酶原的活化。     

Metal-ion- and pH-induced conformational changes of acutolysin D from Agkistrodon acutus venom probed by fluorescent spectroscopy

Acutolysin D isolated from the venom of Agkistrodon acutus is a protein of 44 kDa with marked hemorrhagic and proteolytic activities. The metal-ion- and pH-induced conformational changes of acutolysin D have been studied by following fluorescence and activity measurements. Here we provide evidence for the fact that native holo-acutolysin D adopts two different conformations, native state a, stable in the weak acidic pH range from 5.5 to 7.0 with low activity, and native state b, stable in the weak alkaline pH range from 8.0 to 9.0 with high activity. Holo-acutolysin D has an optimum pH of 9.0 for caseinolytic activity and a maximum fluorescence at pH 9.0. The protein adopts the most stable conformation at pH 9.0. The addition of 1 mM Zn(2+) shifts both the alkali-induced unfolding transition curve and the alkali-induced inactivation curve toward higher pH value but has little effect on the acid-induced unfolding transition curve. No obvious effects on the pH-induced unfolding transition curve and the pH-dependent activity curve have been observed after the addition of 1 mM Ca(2+) to holo-acutolysin D. The results indicate that Zn(2+) is essential for its CA, while Ca(2+) is not essential for its CA. Removal of Ca(2+) and Zn(2+) from the protein enhances its sensitivity to pH and significantly reduces its overall stability during acid-induced denaturation. The kinetic results of the demetalization of holo-acutolysin D show that the demetalization rate constant K(1) for a slower reaction linearly decreases with the pH increase from 5.0 to 9.0, while K(2) for the faster reaction linearly increases with the pH change from 5.0 to 7.0. It is also evident from the present work that the free Zn(2+)-induced inactivation in the pH range from 8.0 to 9.0 should be attributed to the effect of Zn(OH)(2) precipitation on the protein.     

蕲蛇酶在实验性动物的尿,粪排泄率和血浆蛋白结合率研究

用１３１Ｉ标记方法研究蕲蛇酶在大鼠尿、粪中排泄情况和与家兔血浆蛋白结合率,结果表明,其自大鼠尿中排泄率为结合量的３２．８±ｓ０．４８％,粪中排泄率为４．９６±ｓ０．９９％,与家兔血清蛋白结合率为３０．６３％。     

蕲蛇酶对动物实验性血栓的防栓和溶栓作用

采用大鼠颈动脉－颈外静脉回路循环形成的血小板性动脉血栓,用兔脑粉浸出液诱导的大鼠下腔静脉血栓以及用凝血酶诱导的兔耳缘静脉血栓,作为实验性动脉及静脉血栓模型,并分别用阿斯匹林和尿激酶作为阳性对照药,以观察蕲蛇酶对血栓形成的影响。不同剂量的蕲蛇酶（６００,３００和１５０μｇ／ｋｇｉｖ）能使大鼠动脉和静脉血栓形成减少,并呈量效关系。蕲蛇酶对家兔耳缘静脉血栓形成亦表现抑制作用并促进血栓消褪。３００和６００μｇ／ｋｇ对家兔已形成的动脉和静脉血栓,能促使消褪,提示蕲蛇酶亦有溶栓作用     

五步蛇蛇毒磷脂酶A_2的纯化及部分性质

经Sephadex G-75和QAE-Sephadex A-50离子交换层析等方法,从湖南产五步蛇(Agkistrodon acutus)蛇毒中纯化一种均一的酸性磷脂酶A_2。SDS-PAGE测得分子量为15.8kD,按氨基酸残基计算其分子量为14.352kD,IEF-PAGE测得等电点为5.32。氨基酸组份分析表明磷脂酶A_2分子由128个氨基酸残基组成,富含Asp和Glu,不含中性糖。PLA_2酶活性的最适温度为45℃,最适pH为8.5左右,没有抗胰蛋白酶的活性,具一定的热稳定性。K~+、Ca~(++)和Na~+离子激活,而Cd~(++)、Sn~(++)、Cu~(++)、Li~+、Hg(++)、Zn~(++)、Fe~(++)和Co~(++)离子可抑制或完全丧失酶活力。手工微量顺序分析测得PLA_2分子N-末端氨基酸为Leu。此酶对小白鼠的LD_(50)至少大于10mg/kg(ip)。     

濒危植物秦岭石蝴蝶的生态学特性及濒危原因分析

通过野外调查和随机取样法,对仅产于陕西勉县的中国特有濒危植物秦岭石蝴蝶( Petrocosmea qinlingensis W. T. Wang)群落的维管植物组成、垂直结构和分布区类型及其种群特征和土壤化学性质进行了调查和分析;在此基础上,初步探讨了该种类的濒危原因。调查结果显示：秦岭石蝴蝶为喜阴植物,仅分布于山体海拔约640 m的区域,种群面积仅约42 m2;土壤为黄棕壤,呈中性(pH 6.50),土壤中有机质含量较高,全氮、全磷和全钾含量较低,有效铁、有效镁、有效钠和有效钙含量则较高;秦岭石蝴蝶种群中个体数量约1000株,多生长于覆有土壤或苔藓的岩石上,也有部分成年个体生长在裸露且瘠薄的岩石上。秦岭石蝴蝶群落中共有维管植物28种,隶属于23科28属;其中,蕨类植物3科4属4种,裸子植物1科1属1种,被子植物19科23属23种,优势科和优势属不明显。秦岭石蝴蝶群落垂直结构明显,可分为乔木层、灌木层和草本层,其中,乔木层优势种为杜仲( Eucommia ulmoides Oliver),灌木层优势种为华西小石积( Osteomeles schwerinae Schneid.),草本层优势种为裂叶荨麻( Urtica lobatifolia S. S. Ying)。该群落维管植物科的分布型以热带分布型科为主,其中泛热带分布型科占明显优势;属的分布型以温带分布型属为主,其中北温带分布型属占优势;中国特有分布的科和属均很少;总体上看,该群落具有暖温带向亚热带过渡的特点。在秦岭石蝴蝶种群的不同样方中,成年个体和幼苗数量均有一定差异,成年个体占14.6%~37.5%,幼苗占61.3%~80.0%,幼苗数量明显高于成年个体;各样方的单株叶片数为7~9,冠幅为6.0~7.2 cm,大多数样方的单株结实量小于4,表明在同一个种群的不同生境中秦岭石蝴蝶的分布和生长状况有明显差异。根据调查结果,推测种群规模较小、分布范围狭窄以及人为干扰可能是造成秦岭石蝴蝶濒危的主要原因,而人为干扰是其中的重要原因。