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1.
1. The loss in activity of crystalline pepsin solutions when exposed to beta and gamma rays from radium or to ultra-violet light is accompanied by a corresponding decrease in pepsin protein. 2. The rate of inactivation by ultra-violet light depends upon the pH and is a maximum at about pH 2.0.  相似文献   

2.
3.
1. A method has been described for isolating a crystalline protein with high proteolytic activity from bovine gastric juice by means of precipitation with magnesium sulfate and fractionation of the precipitate with acetone and magnesium sulfate. 2. The crystalline protein obtained in this way has the same crystalline form, optical activity, and specific activity, as determined by a number of methods, as does the crystalline protein previously isolated from swine gastric mucosa. 3. The solubility of the two preparations, however, is additive so that they are different although very closely related proteins.  相似文献   

4.
Crystalline trypsinogen is most readily and completely transformed into trypsin by means of enterokinase in the range of pH 5.2–6.0 at 5°C. and at a concentration of trypsinogen of not more than 0.1 mg. per ml. The action of enterokinase under these conditions is that of a typical enzyme. The process follows closely the course of a catalytic unimolecular reaction, the rate of formation of trypsin being proportional to the concentration of enterokinase added and the ultimate amount of trypsin formed being independent of the concentration of enterokinase. The catalytic action of enterokinase on crystalline trypsinogen in dilute solution at pH more alkaline than 6.0 and in concentrated solution at pH even slightly below 6.0 is complicated by the partial transformation of the trypsinogen into inert protein which can no longer be changed into trypsin even by a large excess of enterokinase. This secondary reaction is catalyzed by the trypsin formed and the rate of the reaction is proportional to the concentration of trypsin as well as to the concentration of trypsinogen in solution. Hence under these conditions only a small part of the trypsinogen is changed by enterokinase into trypsin while a considerable part of the trypsinogen is transformed into inert protein, the more so the lower the concentration of enterokinase used. The kinetics of the formation of trypsin by means of enterokinase when accompanied by the formation of inert protein can be explained quantitatively on the theoretical assumption that both reactions are of the simple catalytic unimolecular type, the catalyst being enterokinase in the first reaction and trypsin in the second reaction.  相似文献   

5.
6.
1. From leaves of Portulaca grandiflora, a substance which inhibitedthe IAA-induced elongation of Avena coleoptile sections andthe adventitious root formation of Raphanus hypocotyl cuttingswas separated by means of thin layer chromatography. It wasisolated and crystallized. 2. On paper chromatograms, this substance gave the same Rf valuesas the inhibitor from leaves of Xanthium strumarium and thatfrom leaves of Helianthus tuberosus ("heliangine"), namely,Rf0.9 in ammoniacal isopropanol, Rf 0.85 in methanol-water andRf 0.0 in n-hexane-water. On thin layer chromatograms, however,these inhibitors were clearly separated from each other. 3. Infra-red absorption spectrum also indicated that this substanceis identical with neither xanthinin nor heliangine. 1 Contribution No. 8 from the Botanical Gardens, Faculty ofScience, University of Tokyo, Koishikawa, Tokyo  相似文献   

7.
毛花猕猴桃根中的一个新三萜化合物   总被引:5,自引:0,他引:5  
从毛花猕猴桃(Actindia eriantha Benth)的根中分离到三个结晶成分,根据光谱数据(MS,IR,~(12)CNMR,~1HNMR)和化学证明,R_6的结构为2α,3β,24-三羟基-12-烯-28-乌苏酸是一新化合物,其余两个成分分别为二十四碳酸和葡萄糖。  相似文献   

8.
毛花猕猴桃中的两个新三萜化合物   总被引:14,自引:0,他引:14  
从毛花猕猴桃(Actinidia eriantha Benth.)的根中,分离到β-谷甾醇,胡萝卜甙,熊果酸,2α,3α,24-三羟基-12-烯-28-乌苏酸,同时还得到两个新的三萜化合物,命名为毛花猕猴桃酸A(eriatic acid A)和毛花猕猴桃酸B(eriantic acid B)。根据光谱数据及化学反应证明,其结构分别为24-乙酰氧基-2α,3α-二羟基-12-烯-28-乌苏酸和2β,3β,23-三羟基-12-烯-28-乌苏酸。  相似文献   

9.
A new crystalline protein, chymo-trypsinogen, has been isolated from acid extracts of fresh cattle pancreas. This protein is not an enzyme but is transformed by minute amounts of trypsin into an active proteolytic enzyme called chymo-trypsin. The chymo-trypsin has also been obtained in crystalline form. The chymo-trypsinogen cannot be activated by enterokinase, pepsin, inactive trypsin, or calcium chloride. There is an extremely slow spontaneous activation upon standing in solution. The activation of chymo-trypsinogen by trypsin follows the course of a monomolecular reaction the velocity constant of which is proportional to the trypsin concentration and independent of the chymotrypsinogen concentration. The rate of activation is a maximum at pH 7.0–8.0. Activation is accompanied by an increase of six primary amino groups per mole but no split products could be found, indicating that the activation consists in an intramolecular rearrangement. There is a slight change in optical activity but no change in molecular weight. The physical and chemical properties of both proteins are constant through a series of fractional crystallizations. The activity of chymo-trypsin decreases in proportion to the destruction of the native protein by pepsin digestion or denaturation by heat or acid. Chymo-trypsin has powerful milk-clotting power but does not clot blood plasma and differs qualitatively in this respect from the crystalline trypsin previously reported. It hydrolyzes sturin, casein, gelatin, and hemoglobin more slowly than does crystalline trypsin but the hydrolysis of casein is carried much further. The hydrolysis takes place at different linkages from those attacked by trypsin. The optimum pH for the digestion of casein is about 8.0–9.0. It does not hydrolyze any of a series of dipeptides or polypeptides tested. Several chemical and physical properties of both proteins have been determined.  相似文献   

10.
A crystalline protein compound has been isolated from a solution containing crystalline trypsin and crystalline soybean inhibitor. The protein consists of about equal weights of trypsin and of the inhibitor. Denaturation by heat or by alkali resolves the compound into its components.  相似文献   

11.
万年蒿中两个新贝壳杉烷型二萜的分离与结构测定   总被引:4,自引:0,他引:4  
自菊科蒿属植物万年蒿(Artemisia sacrorum Ledeb.)地上部分首次分得3个单体化合物(两个贝壳杉烷型二萜和一个酸性化合物),经理化常数测定及光谱分析(UV,IR,~1H-NMR,~(13)C-NMR,MS)鉴定其结构分别为3α,16α-二羟基贝壳杉烷-200-O-β-D-葡萄糖甙(Ⅰ)(3α,16α-dihydroxykaurane-20-O-β-D-glucoside(Ⅰ)),3α,6α-二羟基贝壳杉烷-19-O-β-D-葡萄糖甙(Ⅱ)(3α,16α-dihydroxykaurane-19-O-β-D-glucoside(Ⅱ))和1,4-二咖啡酰奎宁酸(Ⅲ)(1,4-dicaffeylquinic acid(Ⅲ))。(Ⅰ)和(Ⅱ)为两个未见报道的新化合物。  相似文献   

12.
随着免疫组织化学研究的进展,各种新的肿瘤标记物的发现对肿瘤的来源和罕见肿瘤的诊断、以及转移瘤原发部位的确定,提供了客观而可靠的依据。但是免疫组化还面临不少问题。越来越多的肿瘤标记物的相对特异性和交叉反应,未分化或低分化肿瘤不表达有关抗原,给诊断带来困难。尤其是软组织肿瘤,由于组织起源的多样性和多向分化的潜能,瘤细  相似文献   

13.
Three kinds of enzymes, agarase, β-1,4-mannanase, and β-1,3-xylanase, required for isolation of protoplasts from the red alga Bangia atropurpurea (Roth) C. Ag. were prepared from bacterial culture fluids of Vibrio sp. PO-303, Vibrio sp. MA-138, and Alcaligenes sp. XY-234, respectively, isolated from the sea environment. The optimal pH of all enzymes was around 7.5. Suitable conditions for protoplast isolation from B. atropurpurea were examined. The pretreatment of the fronds with pa-pain solution (20 mM Mes buffer, pH 7.5, containing 2% papain and 0.5 M mannitol) contributed to successful protoplast isolation. When razor-cut fragments of the fronds (about 200 mg in fresh weight) immersed in 20 mM Mes buffer, 7.5, containing 0.5 M mannitol and one unit each of agarase, β-1,4-mannanase, and β-1,3-xylanase were incubated at 22°C for 90 min with gentle agitation, 5.7 × 106 protoplasts were released from them. Many protoplasts regenerated into fronds of regular or irregular shape.  相似文献   

14.
Methods are described for the isolation and crystallization of trypsinogen, trypsin, a substance which inhibits trypsin, and an inhibitor-trypsin compound. Analyses and some of the properties of these compounds are given.  相似文献   

15.
罗汉果中甘露醇的分离和鉴定   总被引:11,自引:1,他引:11  
徐位坤  孟丽珊  李仲瑶   《广西植物》1990,10(3):254-255
从罗汉果的新鲜果实中提取分离出一种非三萜葡萄糖甙的甜味成分,经化学和光谱测定鉴定为D-甘露醇。  相似文献   

16.
阜新海州组侧羽叶属一新种及其表皮构造   总被引:2,自引:0,他引:2  
本文报道了辽宁西部阜新地区下白垩统海州组本内苏铁类植物侧羽叶属的一个新种,即阜新侧羽叶(新种)[Pterophyllum fuxinense(sp.nov.)]。讨论了海州组植物群的性质。并对新种的形态特征及其表皮构造进行了描述。  相似文献   

17.
Hagen , George L. (The Institute for Cancer Research, Philadelphia, Pa.), James E. Gunckel , and Arnold H. Sparrow . Morphology and histology of tumor types induced by X, gamma and beta irradiation of a tobacco hybrid. Amer. Jour. Bot. 48(8): 691–699. Illus. 1961.—Radiation-induced tumors of an interspecific hybrid, Nicotiana glauca × N. langsdorffii, were of 6 morphological types: white-smooth; green-smooth; green-tomentose; purple-pigmented; green-leafy and stalked, although all intergrades could be found in 1 tumor mass. The morphological responses were essentially the same after treatment with acute X rays, chronic gamma or beta rays. Gamma rays were from an external cobalt-60 source and beta rays from internally deposited P32. The histology of the 6 morphological tumor types was not distinctive in terms of meristem, vascular and surface development, but rather followed an ontogenetic series from non-organoid to organoid. The results are discussed in terms of abnormal genome and physiological imbalances, and are compared to similar responses from infection with crown gall and wound-tumor virus.  相似文献   

18.
似巨型禄丰龙cf.Lufengosaurus magnus在四川盆地自流井组大安寨段的发现,说明自流井组与下禄丰组可以对比,沉积时代应为早侏罗世。  相似文献   

19.
对核糖核酸酶、胰凝乳蛋白酶等近十种蛋白质、氨基酸及其衍生物进行光照研究,发现在强紫外光照后都能产生荧光物,其发射峰的位置在400um左右.光照带芳香氨基酸残基的蛋白质形成荧光物是蛋白质的一个共同的特性.进一步分离这些蛋白荧光物时,发现这些蛋白质受到紫外光照后,有一定的破坏,包括链的断裂和某些氨基酸含量的减少.  相似文献   

20.
孟繁松 《古生物学报》1992,31(6):703-707
报道了采自鄂西晚三叠世九里岗组的植物Radiatifolium magnusum gen. et sp. nov.,并订正了种名 Nilssonia hubeiensis nom. nov..因新属裂片的形态和脉序等与古生代的 Rhipidopsis 有些接近,认为其分类位置属银杏类的可能性较大;依据叶的分裂方式比较简单,裂片大小相差不大等,推测它可能代表银杏类中比较原始的类型.此外,对九里岗组植物群与我国南、北两个晚三叠世植物群的关系也作了扼要的讨论.  相似文献   

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