Cloning of two novel P-III class metalloproteinases from Trimeresurus stejnegeri venom gland

Hemorrhagic toxins are widely distributed in viperid and crotalid snake venoms. Envenomation of Trimeresurus stejnegeri, a member of Crotalidae family, caused potent systemic and local hemorrhage. Up to now, there is no report on hemorrhage toxins from th

Toward an understanding of the molecular mechanism for successful blood feeding by coupling proteomics analysis with pharmacological testing of horsefly salivary glands

Horseflies are economically important blood-feeding arthropods and also a nuisance for humans and vectors for filariasis. They rely heavily on the pharmacological properties of their saliva to get a blood meal and suppress immune reactions of hosts. Little information is available on antihemostatic substances in horsefly salivary glands; especially no horsefly immune suppressants have been reported. By proteomics or peptidomics and coupling transcriptome analysis with pharmacological testing, several families of proteins or peptides, which act mainly on the hemostatic system or immune system of the host, were identified and characterized from 30,000 pairs salivary glands of the horsefly Tabanus yao (Diptera, Tabanidae). They are: (i) a novel family of inhibitors of platelet aggregation including two members, which possibly inhibit platelet aggregation by a novel mechanism and act on platelet membrane, (ii) a novel family of immunosuppressant peptides including 12 members, which can inhibit interferon-gamma production and increase interleukin-10 secretion, (iii) a serine protease inhibitor with 56 amino acid residues containing anticoagulant activity, (iv) a serine protease with anticoagulant activity, (v) a protease with fibrinogenolytic activity, (vi) three families of antimicrobial peptides including six members, (vii) a hyaluronidase, (viii) a vasodilator peptide, which is an isoform of vasotab identified from Hybomitra bimaculata, and interestingly (ix) two metallothioneins, which are the first metallothioneins reported from invertebrate salivary glands. The current work will facilitate the understanding of the molecular mechanisms of the ectoparasite-host relationship and help in identifying novel vaccine targets and novel leading pharmacological compounds.

Comparative study of three short-chain neurotoxins from the venom of Naja kaouthia (Yunnan, China)

Three short-chain neurotoxins named NT-I, NT-II, and NT-III were purified from the venom of Naja kaouthia, a snake distributed throughout the south of Yunnan province, China, by a series of chromatographic steps, including an FPLC Resource S column. Their molecular weights, determined by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) MS, were 6952.19 Da, 6854.92 Da, and 6828.80 Da, respectively. NT-I consisted of 62 amino acid residues, and the other two consisted of 61 amino acid residues, including 8 cysteines. After hydrolysis by endoproteinase Glu-C, their primary sequences were determined. A test of their activities demonstrated that they effectively inhibited muscle contractions induced by electric stimulation. Furthermore, the extent of inhibition caused by NT-II and NT-III was less than that of NT-I. The IC(50)s were 0.04 mug/ml, 0.20 mug/ml, and 0.23 mug/ml for NT-I, NT-II, and NT-III, respectively. Compared with NT-II and NT-III, the higher activity of NT-I may be a result of the amino acid residue substitution Ile36 to Arg36.

A novel short neurotoxin, cobrotoxin c, from monocellate cobra (Naja kaouthia) venom: isolation and purification, primary and secondary structure determination, and tertiary structure modeling

A novel short neurotoxin, cobrotoxin c (CBT C) was isolated from the venom of monocellate cobra (Naja kaouthia) using a combination of ion-exchange chromatography and FPLC. Its primary structure was determined by Edman degradation. CBT C is composed of 61 amino acid residues. It differs from cobrotoxin b (CBT B) by only two amino acid substitutions, Thr/Ala11 and Arg/Thr56, which are not located on the functionally important regions by sequence similarity. However, the LD50 is 0.08 mg/g to mice, i.e. approximately five-fold higher than for CBT B. Strikingly, a structure-function relationship analysis suggests the existence of a functionally important domain on the outside of Loop III of CBT C. The functionally important basic residues on the outside of Loop III might have a pairwise interaction with alpha subunit, instead of gamma or delta subunits of the nicotinic acetylcholine receptor (nAChR). (C) 2002 Elsevier Science Inc. All rights reserved.

A novel high molecular weight metalloproteinase cleaves fragment F1 of activated human prothrombin

A hemorrhagic proteinase, jerdohagin, was purified from Trimeresurus jerdonii venom by gel filtration and ion-exchange chromatographies. It was a single chain polypeptide with an apparent molecular weight of 96 kDa as estimated by SDS-PAGE under the non-reducing and reducing conditions. Internal peptide sequencing indicated that it consisted of metalloproteinase, disintegrin-like and cysteine-rich domains and belonged to the class III snake venom metalloproteinases (class P-III SVMPs). Like other typical metalloproteinases, hemorrhagic activities of jerdohagin were completely inhibited by EDTA, but not by PMSF. Jerdohagin preferentially degraded a-chain of human fibrinogen. Interestingly, jerdohagin did not activate human prothrombin, whereas it cleaved human prothrombin and fragment F1 of activated human prothrombin. (C) 2004 Elsevier Ltd. All rights reserved.

B itte r an d Sw e e t /Um am i Ta s te Re c ep to rs w ith D iffe ren tly Evo lu tio n a ry Pa thw ays

通过生物信息学和系统发育学分析,研究了苦味受体和甜味/鲜味受体的进化途径。结果显示,苦味受体 和甜味/鲜味受体在进化上具有远相关,并且具有不同的进化途径,提示这可能是导致这些受体具有不同功能,传 导不同味觉的原因。

肝素钠的生产及其存在的问题和解决的方法(III)——无蛋白品和精品的生产

从技术路线、原料控制和设备设施等方面对肝素钠无蛋白品和精品的生产进行了论述，并就如何提高品质收率和目前存在的一些问题进行探讨。