猪精子凝集素在精卵结合中的作用机制

猪精子凝集素（ＢＳＬ）位于精子头部,既与精子蛋白结合,亦与透明带糖蛋白ＺＰ３结合。并且ＢＳＬ自身分子间亦会聚合。与ＺＰ３结合的片段亦结合于岩藻素－Ｓｅｐｈａｒｏｓｅ亲和柱,但不与胎球蛋白－Ｓｅｐｈａｒｏｓｅ柱结合。该片段具有较强的抑制精卵结合的活性。ＢＳＬ经ＮＢＳ修饰后,血凝活力大大下降,同时推动与精子结合的活性,但不影响它与ＺＰ３的结合。修饰后的ＢＳＬ亦显著抑制精卵结合。表明ＢＳＬ以两个不同的部     

格拉姆柱花草(Stylosanthes gracilis H.B.K.cv.Graham)凝集素的纯化与性质研究

为了探讨凝集素在豆科植物与根瘤菌的识别过程中的作用,用ＤＥＡＥ－３２离子交换层析和ＳｅｐｈａｄｅｘＧ－１５０凝胶过滤分离、纯化格拉姆柱花草种子凝集素（ＳＧＬ）,其分子量约为４５ｋＤ,由两个相同的亚基组成,等电点约ｐＨ５．８,它是一种糖蛋白,含糖量约为２．６％．ＳＧＬ的热稳定性强．ＳＧＬ的血凝活性能被甘露糖所抑制．ＳＧＬ对红细胞的凝集作用可能具有种属专一性;ＳＧＬ具有强的促有丝分裂作用;荧光标记实验显示：９株能与格拉姆柱花草植株结瘤的菌株有７株能与ＳＧＬ结合,６株不能与之结瘤的菌株,只有１株能与ＳＧＬ结合,这表明不同根瘤菌菌株对ＳＧＬ的结合能力,和它们在格拉姆柱花草上结瘤能力之间可能具有一定的生物学相关性．     

猪精子凝集素的纯化,性质及其作用

用胎球蛋白－Ｓｅｐｈａｒｏｓｅ亲和层析和凝胶过滤层析从精子和精浆中分离纯化了猪精子凝集素（简称ＢＳＬ）。ＢＳＬ的血凝活性只被若干糖蛋白和聚糖所抑制。ＢＳＬ的分子量为５６ｋｄ,由分子量分别为１３．６ｋｄ（β）和１６．０ｋｄ（α）的两个不同的亚基以α１β３所组成。ＢＳＬ为糖蛋白,含中性糖３．２％,不含唾液酸。用ＥＬＩＳＡ法测定猪精子中ＢＳＬ的含量及分布,表明７０％嵌入在精子膜中,２５％结合在精子表面,     

大瓶螺凝集素的分离纯化及部分性质研究

大瓶螺蛋白腺经磷酸盐缓冲液抽提、硫酸铵分级沉淀、Ｓｅｐｈａｄｅｘ Ｇ－１００和Ｓｅｐｈａｒｏｓｅ ４Ｂ凝胶过滤,可获得在不连续ＰＡＧＥ（ｐＨ４．３和ｐＨ８．９）上显示单一蛋白质染色带的大瓶螺凝集素（ＡＧＬ）。该凝集素对人血红细胞无血型专一性,但对Ａ型血红细胞胞的凝集作用最强。ＡＧＬ的血凝活力可被乳糖或半乳糖所抑制。ＡＧＬ分子中的中性糖含量为０．２４ｍｇ／ｍｇ蛋白质。用ＳＤＳ－ＰＡＧＥ法测得其亚基分     

大瓶螺凝集素的分离纯化及部分性质研究

大瓶螺蛋白腺经磷酸盐缓冲液抽提、硫酸铵分级沉淀、ＳｅｐｈａｄｅｘＧ－１００和Ｓｅｐｈａｒｏｓｅ４Ｂ凝胶过滤,可获得在不连续ＰＡＧＥ（ｐＨ４．３和ｐＨ８．９）上显示单一蛋白质染色带的大瓶螺凝集素（ＡＧＬ）．该凝集素对人血红细胞无血型专一性,但对Ａ型血红细胞的凝集作用最强．ＡＧＬ的血凝活力可被乳糖或半乳糖所抑制．ＡＧＬ分子中的中性糖含量为０．２４ｍｇ／ｍｇ蛋白质．用ＳＤＳ－ＰＡＧＥ法测得其亚基分子量为１５０００,且只有一种亚基．ＡＧＬ中Ｃｙｓ和Ｐｈｅ的含量较高,并较耐热．     

天花粉同工凝集素—1双链的拆分和鉴定

天花粉同工凝集素－１经巯基乙醇还原,碘代乙酰胺保护,其链间二硫键被打开,但仍非共价结合在一起。我们利用尿素变性的Ｑ－Ｓｅｐｈａｒｏｓｅ离子交换层析分离了此凝集素的两条链。氨基酸组成测定与其他３种肽链作一比较,它们都含有较多的酸性和羟基氨基酸。蛋白质印迹显示ＴＫＬ的抗血清不仅能与ＴＫＬ－１的两条链分别分应,也能与天花粉毒蛋白及蓖麻毒蛋白的Ａ链起作用。溴化氰裂解的ＳＤＳ－ＰＡＧＥ肽谱表明天花粉凝集素的     

红花菜豆(矮生红花变种)凝集素分子的色氨酸残基修饰与其活性的关系

用各种化学试剂修饰红花菜豆（Ｐｈａｓｅｏｌｕｓｃｏｃｃｉｎｅｕｓｖａｒｒｕｂｒｏｎａｎｕｓ,Ｂｅｒｒｙ）凝集素（简称ＰＣＬ）分子,测定与其活性相关的氨基酸残基．经ＮＢＳ修饰表明ＰＣＬ具有８个Ｔｒｐ残基,其中４个暴露于分子表面,此４个Ｔｒｐ残基被修饰后,ＰＣＬ的凝血活性完全丧失．比较ＰＣＬ修饰前后的ＣＤ光谱表明修饰不改变其二级结构。修饰Ｔｙｒ,Ａｒｇ,Ｈｉｓ残基和游离氨基及羧基不影响ＰＣＬ的血凝活性．巯基也不是血凝活性所必需,但是ＰＣＬ分子中的二硫键被还原,或被ＣＮＢｒ分解为两个片断则使蛋白质丧失血凝活性,提示分子的完整结构对ＰＣＬ的血凝活力是重要的     

天花粉同工凝集素－1双链的拆分和鉴定

天花粉同工凝集素－１经巯基乙醇还原,碘代乙酰胺保护,其链间二硫键被打开,但仍非共价结合在一起。我们利用尿素变性的Ｑ－Ｓｅｐｈａｒｏｓｅ离子交换层忻分离了此凝集素的两条链。氨基酸组成测定与其他３种肽链作一比较,它们都含有较多的酸性和羟基氨基酸。蛋白质印迹显示ＴＫＬ的抗血清不仅能与ＴＫＬ－１的两条链分别反应,也能与天花粉毒蛋白及蓖麻毒蛋白的Ａ链起作用。溴化氰裂解的ＳＤＳ－ＰＡＧＥＲ肽谱表明天花粉凝集素的两条链与天花粉毒蛋白含有类似的裂解片段,在分子量１６ｋｄ左右有相同的电泳条带。ＴＫＬ－１两亚基的Ｎ末端序列已经测定,同源性比较发现其３３ｋｄ亚基的Ｎ末端序列与天花粉毒蛋白、蓖麻毒蛋白的一些肽段类似。迄今已有的证据表明ＴＫＬ与ＴＣＳ等是一些非常相关的蛋白质。     

红花菜豆（矮生红花变种）凝集素分子的色氨酸残基修饰与其活性的关系

用各种化学试剂修饰红花菜豆凝集素分子,测定与其活性相关的氨基酸残基,经ＮＢＳ修饰表明ＰＣＬ具有８个Ｔｒｐ残基,其中４个暴露于分子表面,此４个Ｔｒｐ残基被修饰后,ＰＬＣ的凝血活性完全丧失,比较ＰＣＬ修饰前后的ＣＤ光谱表明修饰不改变其二级结构。修饰Ｔｙｒ,Ａｒｇ,Ｈｉｓ残基和游离氨基及羧基不影响ＰＣＬ的血凝活性,巯基也不是血凝活性所必需,但是ＰＣＬ分子中二硫键被还的,或被ＣＮＢｒ分解为两个片断则使蛋白     

^15N标记蛋白GAL4（62）的2D NMR实验

利用自编的脉冲程序,采用预饱和和自旋锁定对水峰进行双重抑制的方法,得到了＾１５Ｎ标记蛋白ＧＡＬ４（６２）的２Ｄ＾１Ｈ－＾１５ＮＨＳＱＣ、ＨＳＱＣ－ＮＯＥＳＹ、ＨＳＱＣ－ＴＯＣＳＹ谱,并对这几个谱在蛋白质＾１Ｈ谱的归属中所到的作用作了讨论。     

三齿草藤(Vicia bungei Ohwi)凝集素糖组分的高效液相色谱分析

本文报道经亲和层析纯化的三齿草藤凝集素(VBL)的糖含量和糖组分的测定结果。经酚-硫酸法测得VBL的总糖含量为4.7％。应用高效液相色谱法对一系列已知标准单糖的定性定量分析条件进行了探索,选用乙腈-水-甲醇=60:30:5体系作流动相,YWG-NH_2作固定相,在高效液相色谱仪中测出VBL含有核糖和鼠李糖,二者摩尔数之比为9.4:1。     

A sialic acid-specific lectin from the slug Limax flavus

The slug, Limax flavus, contains a lectin that appears to be highly specific for sialic acid residues of glycoproteins. The carbohydrates which inhibited the hemagglutinating activity of the slug lectin and the concentration of the carbohydrate which gave a 50% inhibition are as follows: N-acetylneuraminic acid, 0.13 mm; N-glycolylneuraminic acid, 0.90 mm; d-glucosamine, 4.9 mm; d-galactosamine, 7.6 mm; N-acetyl-d-glucosamine, 23 mm; and N-acetyl-d-galactosamine, 24 mm. d-Galactose, d-glucose, d-mannose, α-methyl-d-glucoside, α-methyl-d-mannoside, l-arabinose, d-xylose, l-fucose, d-glucuronic acid, lactose, and sucrose were found to be ineffective as inhibitors of the hemagglutinating activity of the slug lectin. Hemagglutination by slug lectin was strongly inhibited by bovine submaxillary mucin and fetuin but not by sialic acid-free bovine submaxillary mucin or fetuin.     

从绿藻礁膜（Monostroma nitidum Wittr）分离半乳糖专一的凝集素

礁膜（Monostroma nitidum Wittr）经 25%～80%硫酸铵分级、DEAE-纤维素52离子交换层析和Sephadex G-200凝胶过滤层析,得到纯化礁膜凝集素（Monostroma nitidum lectin,MNL）,在SDS-PAGE上显示单一蛋白染色带. 用Sephadex G-200层析测得其分子质量为66.6 kD, 用SDS-PAGE测得其分子质量为66.2 kD．该凝集素可以凝集人A、B、AB、O型红细胞,且凝集活性相同. 在对人（A、B、AB、O）、兔、鲤、鲫、鼠、羊、鸡、狗的红细胞凝集作用中,兔凝集作用最强．该凝集素在pH 4.00～10.53范围内均有活性,但在pH 5.20～9.40范围内活性最大．经100 ℃热处理30 min后,该凝集素对兔红细胞血凝活性保留25%,活性最大的温度范围为25～55 ℃．MNL被EDTA抑制,最小抑制浓度为3.13 mmol/L,但对 Ca^２＋和Mg^２＋不敏感．该凝集素凝集兔红细胞的作用不被D -果糖、D-甘露糖、D-葡萄糖、蔗糖、麦芽糖、γ-球蛋白、牛甲状腺球蛋白所抑制,但被D- 半乳糖和乳糖抑制,最小抑制浓度分别为5 mmol/L和2.5 mmol/L．     

Isolation and some properties of a lectin from the venom of the Vietnamese scorpion Buthus occitanus sp

A lectin was isolated from the venom of scorpion Buthus occitanus sp. by means of Sephadex G-50 gel filtration and CM-cellulose ion exchange chromatography. The homogeneous lectin preparation consisted of homodimeric molecules with a subunit Mr of 9.3 kDa. Glycine, alanine, and serine dominated in the lectin amino acid composition. The lectin was a glycoprotein containing 20% carbohydrates (predominantly mannose and glucose). Trypsin-treated murine erythrocytes agglutinated at the lectin concentration of 32 micrograms/ml. Hemagglutination was inhibited by carbohydrates (L-fucose > D-glucose > L-rhamnose > D-xylose). The lectin revealed no phospholipase or hyaluronidase, nor toxic activity.     

黑色菜豆(Phaseolus sp.)凝集素的纯化和性质

黑色菜豆(phaseolussp.)种子中含有对人A型血专一凝集的凝集素。用猪胃粘蛋白-Sepharose 4B作亲和吸附剂和Sephadex G-200凝胶过滤,可以纯化这种凝集素。纯化的凝集素在pH8.9,Tris-EDTANa_2-borate缓冲液的PAGE中,呈现单一蛋白带;酚-硫酸法测得总糖含量为3.22％。在SDS-PAGE中发现其分子由两种亚基所组成,亚基分子量分别为38,000和35,000。当凝集素浓度分别为0.98μg/ml和1.95μg/ml时能强烈地凝集人A型和AB型血细胞。在凝集素浓度高达500μg/ml时,B型血细胞能发生弱凝集反应,但对O型血和兔红细胞则完全不发生凝集反应。其凝集活性可被GalNAC、L-Fuc、猪甲状腺球蛋白和卵粘蛋白所抑制。该凝集素对人外周血中淋巴细胞的转化率达80％,细胞分裂比率高达37.1％;氨基组成分析表明,凝集素分子中Asp和Glu含量较高,而cys和Met含量很低。     

Photosynthetic rate and lectin activity of soybean leaves after inoculation with rhizobia together with homologous lectin

Nodule bacteria (Bradyrhizobium japonicum) of various activities were preincubated with homologous lectin and then used for inoculating soybean (Glycine max (L.) Merrill) seeds. The effect of this inoculation on the photosynthetic rate, lectin activity in leaves, and plant development at different supply of mineral nitrogen was investigated under the conditions of pot experiments. There was a positive relationship between the photosynthetic rate and the lectin activity of proteins isolated from soybean leaves. Under the conditions of effective symbiosis, activation of functioning of the symbiotic apparatus by preincubation of the rhizobia with lectin exerted an additional stimulating effect on the photosynthetic rate. It is suggested that a relationship between the effectiveness of legume-rhizobium symbiosis and the lectin activity in leaves is mediated by the regulation of photosynthesis through a demand for assimilates in the source-sink system of soybean plants.     

Purification of a lectin from Eugenia uniflora L. seeds and its potential antibacterial activity

Aims: The aim of this work was to analyse the antimicrobial properties of a purified lectin from Eugenia uniflora L. seeds. Methods and Results: The E. uniflora lectin (EuniSL) was isolated from the seed extract and purified by ion‐exchange chromatography in DEAE‐Sephadex with a purification factor of 11·68. The purified lectin showed a single band on denaturing electrophoresis, with a molecular mass of 67 kDa. EuniSL agglutinated rabbit and human erythrocytes with a higher specificity for rabbit erythrocytes. The haemagglutination was not inhibited by the tested carbohydrates but glycoproteins exerted a strong inhibitory action. The lectin proved to be thermo resistant with the highest stability at pH 6·5 and divalent ions did not affect its activity. EuniSL demonstrated a remarkable nonselective antibacterial activity. EuniSL strongly inhibited the growth of Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella sp. with a minimum inhibitory concentration (MIC) of 1·5 μg ml^?1, and moderately inhibited the growth of Bacillus subtilis, Streptococcus sp. and Escherichia coli with a MIC of 16·5 μg ml^?1. Conclusions: EuniSL was found to be effective against bacteria. Significance and Impact of the Study: The strong antibacterial activity of the studied lectin indicates a high potential for clinical microbiology and therapeutic applications.     

A cortical lectin from the oocytes of Rutilus rutilus stimulates mitogenic activity and release of soluble factors from human lymphocyte cultures and inhibits protein synthesis in a cell-free system

1. A cortical granule lectin was isolated from vitellogenic oocytes of a bony fish, the roach Rutilus rutilus. 2. The lectin agglutinates human erythrocytes, is specific for L-rhamnose and is composed of different polypeptide subunits. 3. The lectin is the first lectin of animal origin that inhibits protein-synthesis by a rabbit reticulocyte lysate, and is also mitogenic for human lymphocytes.     

Purification and separation of tomato isolectins by chromatofocusing

Tomato lectin can be rapidly separated from a crude extract of tomato fruit proteins by chromatofocusing. The lectin is recovered from a PBE94 column in two peaks, each with a specific activity comparable to that of lectin purified by affinity chromatography on ovomucoid-Sepharose. Both isolectins consist of a single polypeptide chain (Mr 68,000) and have similar properties.