Proteolysis of synthetic peptides by type A botulinum neurotoxin

Type A botulinum neurotoxin catalyzed the hydrolysis of synthetic peptides based on the sequence of the 25-kD synaptosomal protein SNAP-25. In each peptide, the toxin cleaved at a single glutaminyl-arginine bond corresponding to residues 197 and 198 of SNAP-25, confirming earlier reports on the enzymatic specificity of the toxin in synaptosomal preparations. Metal chelators inhibited catalysis, consistent with a metalloprotease activity. In contrast to tetanus toxin and other botulinum toxin serotypes, type A toxin hydrolyzed relatively short, 17-to 20-residue peptides. In the substrates, SNAP-25 residue 202 and one or more of residues 187–191 were required for efficient hydrolysis, but residues 167–186 and 203–206 were not. The highest rates of hydrolysis were found when the C-terminal residues of the peptides were amidated.     

Peptide Toxins in Sea Anemones: Structural and Functional Aspects

Sea anemones are a rich source of two classes of peptide toxins, sodium channel toxins and potassium channel toxins, which have been or will be useful tools for studying the structure and function of specific ion channels. Most of the known sodium channel toxins delay channel inactivation by binding to the receptor site 3 and most of the known potassium channel toxins selectively inhibit Kv1 channels. The following peptide toxins are functionally unique among the known sodium or potassium channel toxins: APETx2, which inhibits acid-sensing ion channels in sensory neurons; BDS-I and II, which show selectivity for Kv3.4 channels and APETx1, which inhibits human ether-a-go-go-related gene potassium channels. In addition, structurally novel peptide toxins, such as an epidermal growth factor (EGF)-like toxin (gigantoxin I), have also been isolated from some sea anemones although their functions remain to be clarified.     

玫瑰红鹅膏主要肽类毒素的HPLC 测定及其对白色念珠菌的抑制活性

【目的】检测玫瑰红鹅膏中所含肽类毒素及其含量,并对其肽类毒素的抑制白色念珠菌活性进行研究。【方法】采用HPLC和ESI-MS法从玫瑰红鹅膏中分离并鉴定出所含肽类毒素,并采用HPLC法测定其子实体、菌盖及菌柄和菌托混合部分中肽类毒素的含量。同时,采用纸片法研究了玫瑰红鹅膏粗毒液和分离到的单品肽类毒素对白色念珠菌JLC31680和JLC31681的抑菌作用。【结果】分离并鉴定出α-鹅膏毒肽(α-AMA)、β-鹅膏毒肽(β-AMA)和二羟鬼笔毒肽(PHD)等3种肽类毒素。玫瑰红鹅膏子实体中α-AMA、β-AMA、PHD的含量分别为30.3168、6.9932和9.9459 mg/g;菌盖中含量分别为44.9573、11.0798和11.3025 mg/g;菌柄和菌托混合部分中:α-AMA 11.6904 mg/g和PHD 7.9775 mg/g,β-AMA未检出。粗毒液、α-AMA、β-AMA和PHD对白色念珠菌JLC31680均具有很好的抑制作用,抑制率分别达到11.96%、32.52%、23.29%(p<0.01)和15.46%(p<0.05);粗毒液和β-AMA对白色念珠菌JLC31681的最高抑制率分别为10.16%和11.10%(p<0.01),α-AMA对白色念珠菌JLC31681最高抑菌率为6.89%(p<0.05)。【结论】玫瑰红鹅膏中的三种肽类毒素的含量较高,是制备肽类毒素的新资源;其具有抑制白色念珠菌的活性,可开发利用。     

蜘蛛肽类神经毒素研究进展

对目前已知一级结构的蜘蛛肽类神经毒素的结构和生理活性作了扼要的介绍,这类毒素基本上可分为短链（33-40个氨基酸残基）和长链（66-77个氨基酸残基）两大类.不同种属蜘蛛的肽类毒素之间在一级结构上同源性很小,在生理活性机制上有较大差异.其中某些毒素可选择性的作用于昆虫或脊推动物神经突触上钙与钠离子通道,显示出在神经生物学和神经药理学研究上有很大的应用前景.     

Immunization with a synthetic robustoxin derivative lacking disulphide bridges protects against a potentially lethal challenge with funnel-web spider (<Emphasis Type="Italic">Atrax robustus</Emphasis>) venom

The venom of male Atrax robustus spiders is potentially lethal to primates. These spiders have been responsible for a number of human deaths. Robustoxin is the lethal toxin in the venom. It is a highly cross-linked polypeptide that has 42 amino acid residues and four disulphide bridges. If these bridges are broken, the resulting polypeptide is nontoxic. Robustoxin was chemically synthesized with all of its eight cysteine residues protected with acetamidomethyl groups in order to avoid formation of disulphide bridges. The resulting derivative was co-polymerized with keyhole limpet haemocyanin. Two Macaca fascicularis monkeys were immunized with this conjugate. The monkeys were challenged, under anaesthesia, with a potentially lethal dose of male A. robustus crude venom. Both monkeys showed some minor symptoms of intoxication but recovered fully with no adverse after-effects. Immunization with the same immunogen, in the absence of keyhole limpet haemocyanin, did not protect a third monkey. The N-terminal 23 amino acid peptide derived from the sequence of robustoxin was synthesized and conjugated with ovalbumin. A fourth monkey was immunized with this conjugate. However, it was not protected against challenge. The implications of these results for the preparation of synthetic peptide vaccines are discussed.     

A cDNA from pea petals with sequence similarity to pollen allergen, cytokinin-induced and genetic tumour-specific genes: identification of a new family of related sequences

A cDNA isolated from pea petals exhibits extensive similarity to pollen allergen genes, a cytokinin-regulated cDNA from soybean suspension cultures, a partial cDNA preferentially expressed in tobacco genetic tumours, four Arabidopsis expressed sequence tags (ESTs) and fifteen rice ESTs. This diverse family of pollen allergen-likes genes may have a common ancestor or at least share common functional domains. Possession of a putative signal peptide and a presumed extracellular location is a common aspect of this family of sequences.     

间斑寇蛛毒素的蛋白质化学与蛋白质组学研究新进展

间斑寇蛛Latrodectus tredecimguttatus俗称\"黑寡妇\"蜘蛛。其毒素不仅存在于毒腺中,而且存在于其身体的其他部分、卵粒甚至新生幼蛛体内。研究间斑寇蛛毒腺和毒腺外材料中的毒素成分,探明它们之间的异同、进化关系和生物学作用,具有重要的理论和实际意义。现代蛋白质化学和蛋白质组学技术的发展为间斑寇蛛蛋白质和多肽毒素的研究提供了有效手段,从而可以同时从单一纯化蛋白质和组学的层面探究毒素作用的分子基础和作用机制。到目前为止,间斑寇蛛毒素的蛋白质化学与蛋白质组学研究已取得一定的进展,但相关研究尤其是毒腺外材料来源的毒素研究还有待进一步深入。     

α-鹅膏毒肽和二羟鬼笔毒肽的制备和鉴定

α-鹅膏毒(环)肽和二羟鬼笔毒(环)肽是剧毒的鹅膏菌和其它几种致死毒菌中由一些修饰氨基酸组成的环肽毒素.由于α-鹅膏毒肽对真核生物的mRNA合成的专一性抑制和和二羟鬼笔毒肽对肌动蛋白的专一性束缚,因而它们在分子生物学和细胞学研究中具有重要应用,对其需求逐步增加.为此,作者使用了一种改良的毒素提取方法,以制备高效液相色谱从灰花纹鹅膏菌中分离制备α-鹅膏毒肽和二羟鬼笔毒肽,并通过紫外吸收光谱和质谱进行鉴定,表明α-鹅膏毒肽和二羟鬼笔毒肽的分离效果好,纯度高.本方法对其它毒菌中的α-鹅膏毒肽和二羟鬼笔毒肽的分离制备具有同样的应用价值.     

a-鹅膏毒肽和二羟鬼笔毒肽的制备和鉴定(英文)

-鹅膏毒(环)肽和二羟鬼笔毒(环)肽是剧毒的鹅膏菌和其它几种致死毒菌中由一些修饰氨基酸组成的环肽毒素。由于-鹅膏毒肽对真核生物的mRNA合成的专一性抑制和和二羟鬼笔毒肽对肌动蛋白的专一性束缚,因而它们在分子生物学和细胞学研究中具有重要应用,对其需求逐步增加。为此,作者使用了一种改良的毒素提取方法,以制备高效液相色谱从灰花纹鹅膏菌中分离制备-鹅膏毒肽和二羟鬼笔毒肽,并通过紫外吸收光谱和质谱进行鉴定,表明-鹅膏毒肽和二羟鬼笔毒肽的分离效果好,纯度高。本方法对其它毒菌中的-鹅膏毒肽和二羟鬼笔毒肽的分离制备具有同样的应用价值。     

A test of maternal human chorionic gonadotropin during pregnancy as an adaptive filter of human gestations

The risk of abnormalities and morbidity among live births increases with advanced maternal age. Explanations for this elevated morbidity invoke several maternal mechanisms. The relaxed filter stringency (RFS) hypothesis asserts that mothers, nearing the end of their reproductive lifespan, reduce the stringency of a screen of offspring quality in utero based on life-history traits of parity and interbirth interval (IBI). A separate line of research implicates human chorionic gonadotropin (hCG) during pregnancy as a signal of offspring quality. We test the RFS hypothesis directly by examining whether the difference in gestational hCG across consecutive live births varies positively with the mother''s number of previous live births but inversely with her most recent IBI. We applied multivariable regression methods to a unique dataset of gestational hCG for over 500 000 live births from 2002 to 2007. The difference in gestational hCG across mothers'' consecutive live births varies positively with both mothers'' parity and IBI. These associations remain similar among older mothers (35+ years). Findings support the RFS hypothesis for the parity expectation but not for the IBI expectation. Further evidence for the RFS hypothesis among contemporary human gestations would have to invoke screening mechanisms other than hCG.     

中国胯舟蛾属分类研究 （鳞翅目：舟蛾科）

系统整理了中国胯舟蛾属（Syntypistis Turner）的全部种类共20种,包括1新种黑胯舟蛾Syntypistis melana Wu et Fang,sp. Nov. 和2中国新记录种：篱胯舟蛾 Syntypistis hercules (Schintlmeister) comb. Nov.与防胯舟蛾 Syntypistis defector (Schintlmeister) comb. Nov.,后2种均为新组合。文中提供了分种检索表,新种形态描述和外生殖器特征图。模式标本保存在中国科学院动物研究所动物标本馆。