The synthetic peptide SNX-111 corresponding to the sequence of the omega-conopeptide MVIIA from the venom of the marine snail Conus magus is a highly potent and selective antagonist of N-type calcium channels. We have synthesized and characterized a large number of analogs of SNX-111 in order to elucidate the structural features of the peptide involved in blocking N-type calcium channels. Comparison of the binding of SNX-111 and its analogs to rat brain synaptosomal membranes rich in N-type channels revealed that, among the four lysines and two arginines in the molecule, lysine in position 2 and arginines at position 10 and 21 are important for the interaction of SNX-111 with N-type channels. The importance of the middle segment from residues 9 through 14 for this binding interaction was revealed by substitution of the individual residues as well as by the construction of hybrid peptides in which the residues 9-12 in SNX-111 and another conopeptide, SNX-183, corresponding to a peptide SVIB from Conus striatus, were interchanged. Introduction of the sequence SRLM from SNX-111 in place of RKTS in position 9-12 in SNX-183 resulted in a 38-fold increase in affinity.

The isolation of an untriakontapeptide from camel pituitary extracts has been described. Its structure has been determined and shown to be identical to the sequence of carboxyl-terminal 31 amino acids of ovine f-lipotropin.The peptide possesses very low lipotropic activity but significant opiate activity.During the course of isolation of melanotropins from camel pituitary glands (1), we obtained an untriakontapeptide that has an amino-acid sequence identical to the COOH-terminal 31 residues of ovine fl-lipotropin (2-4). This peptide was found to possess opiate activity. This article describes the isolation, amino-acid sequence, and biological activity of the untriakontapeptide. EXPERIMENTALThe starting material was component N, which was obtained by chromatography of fraction D on a carboxymethyl-cellulose column (1). Fraction D was prepared from acid acetone extracts of whole camel (Camelus dromedarius) pituitaries. Component N was purified further by gel filtration on Sephadex G-25 (fine), followed by electrophoresis on Whatman no. 3 MM paper in pyridine-HOAc buffer, pH 3.7 (pyridine-HOAc-H20, 4:40:1150 vol/vol) for 2 hr at 400 V.Trypsin was obtained from Calbiochem and subtilisin from Sigma. Digestions were performed with 1 mg of peptide and 0.02 mg of trypsin or 0.05 mg of subtilisin in 0.2 M NH4OAc, pH 8.0, at 370 for 8 hr for trypsin and 1 hr for subtilisin. The digests were mapped by paper chromatography (butanol-HOAc-H20, 4:1:5 vol/vol) and subsequent high voltage electrophoresis at pH 2.0 [HCOOH (88%)-HOAc-H20, 218:63:719 vol/vol] for 1.5 hr at 2000 V. Maps were sprayed with 1% ninhydrin in ethanol solution and allowed to develop in the dark for 20 hr; the spots were cut out and material was eluted with 0

Cross-coupling reactions between lipophilic terminal alkynes and aryl bromides can be catalyzed by ligated Pd, in the absence of copper, in pure water at ambient temperatures. Small amounts of the nonionic amphiphile PTS assist by virtue of nanometer micelles formed spontaneously in an aqueous medium.

During October 2020–January 2021, we isolated a total of 67 highly pathogenic avian influenza (HPAI) H5N8 viruses from wild birds and outbreaks in poultry in South Korea. We sequenced the isolates and performed phylogenetic analysis of complete genome sequences to determine the origin, evolution, and spread patterns of these viruses. Phylogenetic analysis of the hemagglutinin (HA) gene showed that all the isolates belong to H5 clade 2.3.4.4 subgroup B (2.3.4.4b) and form two distinct genetic clusters, G1 and G2. The cluster G1 was closely related to the 2.3.4.4b H5N8 HPAI viruses detected in Europe in early 2020, while the cluster G2 had a close genetic relationship with the 2.3.4.4b H5N8 viruses that circulated in Europe in late 2020. A total of seven distinct genotypes were identified, including five novel reassortants carrying internal genes of low pathogenic avian influenza viruses. Our Bayesian discrete trait phylodynamic analysis between host types suggests that the viruses initially disseminated from migratory waterfowl to domestic duck farms in South Korea. Subsequently, domestic duck farms most likely contributed to the transmission of HPAI viruses to chicken and minor poultry farms, highlighting the need for enhanced, high levels of biosecurity measures at domestic duck farms to effectively prevent the introduction and spread of HPAI.

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