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Recent Literature

Aldehyde Capture Ligation for Synthesis of Native Peptide Bonds

Monika Raj, Huabin Wu, Sarah L. Blosser, Marc A. Vittoria, Paramjit S. Arora, J. Am. Chem. Soc., Just Accepted Manuscript DOI: 10.1021/jacs.5b03538 Publication Date (Web): May 12, 2015 Copyright © 2015 American Chemical Society

Chemoselective reactions for amide bond formation have transformed the ability to access synthetic proteins and other bioconjugates through ligation of fragments. In these ligations, amide bond formation is accelerated by transient enforcement of an intramolecular reaction between the carboxyl and the amine termini of two fragments. Building on this principle, we introduce an aldehyde capture ligation that parlays the high chemoselective reactivity of aldehydes and amines to enforce amide bond formation between amino acid residues and peptides that are difficult to ligate by existing technologies.

Chemical protein synthesis using a second generation N-acylurea linker for the preparation of peptide-thioester precursors.

Juan B. Blanco-Canosa, Brunello Nardone, Fernando Albericio, Philip E. Dawson, J. Am. Chem. Soc., Just Accepted Manuscript DOI: 10.1021/jacs.5b03504 Publication Date (Web): May 15, 2015 Copyright © 2015 American Chemical Society

The broad utility of Native Chemical Ligation (NCL) in protein synthesis has fostered a search for methods that enable the efficient synthesis of C-terminal peptide-thioesters, key intermediates in NCL. We have developed an N-acylurea (Nbz) approach for the synthesis of thioester peptide precursors that efficiently undergo thiol exchange yielding thioesterpeptides, and subsequently NCL reaction. However, the synthesis of some glycine rich sequences revealed limitations, such as diacylated products that cannot be converted into N-acylurea peptides. Here, we introduce a new N-acylurea linker bearing an o-amino(methyl)aniline (MeDbz) moiety that enables in a more robust peptide chain assembly. The generality of the approach is illustrated by the synthesis of a pentaglycine sequence under different coupling conditions including microwave heating at coupling temperatures up to 90 °C, affording the unique and desired N-acyl-N’-methylacylurea (MeNbz) product. Further extension of the method allowed the synthesis of all 20 natural amino acids and their NCL reactions. The kinetic analysis of the ligations using model peptides shows the MeNbzpeptide rapidly converts to arylthioesters that are efficient at NCL. Finally, we show that the new MeDbz linker can be applied to the synthesis of cysteine rich proteins such the cyclotides Kalata B1 and MCoTI-II through a one cyclization / folding step in the ligation / folding buffer. The MeNbz linker is fully compatible with the most demanding acylation methods used in peptide synthesis and represents a robust solution to the challenge of synthesizing C-terminally activated peptides.

Identification and Characterization of the First Cathelicidin from Sea Snakes with Potent Antimicrobial and Anti-inflammatory Activity, and Special Mechanism.

Wei L, Gao J, Zhang S, Wu S, Xie Z, Ling G, Kuang Y, Yang Y, Yu H, Wang Y., J Biol Chem. 2015 May 26. doi:10.1074/jbc.M115.642645. [Epub ahead of print]

Cathelicidins are a family of gene-encoded peptide effectors of innate immunity found exclusively in vertebrates. They play pivotal roles in host immune defense against microbial invasions. Dozens of cathelicidins have been identified from several vertebrate species. However, no cathelicidin from marine reptiles has been characterized before. Here we report the identification and characterization of a novel cathelicidin (Hc-CATH) from the sea snake Hydrophis cyanocinctus. Hc-CATH is composed of 30 amino acids and the sequence is KFFKRLLKSVRRAVKKFRKKPRLIGLSTLL. Circular dichroism spectroscopy and structure modeling analysis indicated that Hc-CATH mainly assumes an amphipathic alpha-helical conformation in bacterial membrane-mimetic solutions. It possesses potent, broad-spectrum and rapid antimicrobial activity. Meanwhile, it is highly stable and shows low cytotoxicity toward mammalian cells. The microbial killing activity of Hc-CATH is executed through the disruption of cell membrane and lysis of bacterial cells. Besides, Hc-CATH exhibited potent anti-inflammatory activity by inhibiting the LPS-induced production of nitric oxide (NO) and pro-inflammatory cytokines such as TNF-α, IL-1β and IL-6. Hc-CATH could directly bind with LPS to neutralize its toxicity, and it also could bind to Toll-like receptor 4 (TLR4/MD2 complex), which therefore inhibits the binding of LPS to TLR4/MD2 complex and the subsequent activation of LPS-induced inflammatory response pathways. Taken together, our study demonstrates that Hc-CATH, the first cathelicidin from sea snake with both antimicrobial and anti-inflammatory activity, is a potent candidate for the development of peptide antibiotics. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.

Different Neuropeptides Are Expressed in Different Functional Subsets of Cholinergic Excitatory Motorneurons in the Nematode Ascaris suum

Christopher J. Konop, Jennifer J. Knickelbine, Molly S. Sygulla, Martha M. Vestling, andAntony O. W. Stretton, ACS Chem. Neurosci., Article ASAP DOI: 10.1021/cn5003623 Publication Date (Web): March 26, 2015 Copyright © 2015 American Chemical Society

Neuropeptides are known to have dramatic effects on neurons and synapses; however, despite extensive studies of the motor neurons in the parasitic nematode Ascaris suum, their peptide content had not yet been described. We determined the peptide content of single excitatory motor neurons by mass spectrometry and tandem mass spectrometry. There are two subsets of ventral cord excitatory motor neurons, each with neuromuscular output either anterior or posterior to their cell body, mediating forward or backward locomotion, respectively. Strikingly, the two sets of neurons contain different neuropeptides, with AF9 and six novel peptides (As-NLP-21.1–6) in anterior projectors, and the six afp-1 peptides in addition to AF2 in posterior projectors. In situ hybridization confirmed the expression of these peptides, validating the integrity of the dissection technique. This work identifies new components of the functional behavioral circuit, as well as potential targets for antiparasitic drug development.






New AAPPTec Catalog

AAPPTec has just released its latest printed catalog of amino acid derivates, resins and reagents for peptide synthesis. The new catalog features over 2500 high quality chemicals, including alkenyl amino acids used to form stapled peptides, azidoamino acids utilized in “click” chemistry, pseudoprolines, fluorescent reagents, beta-homo amino acids in addition to standard Fmoc- or Boc- prorected amino acids.

Send an email to to request your copy or go to

Spirit HPLC Columns

High pH reversed phase chromatography is becoming a powerful and highly useful technique in proteome analysis. It has been successfully used as a first dimension peptide separation technique in shotgun proteomic experiments. AAPPTec’s Spirit peptide columns and protein columns are ideally suited for high pH separations. Spirit columns are specially manufactured to provide stability, reproducibility and high resolution at high pH. In fact, Spirit HPLC columns provide high performance and stability over a wide range of pH conditions, from very low to high.

For more information about Spirit HPLC columns, go to the Spirit HPLC Column page of the AAPPTec web site or send an email to

Fluorescent Dyes

Fluorescence labeled peptides are used to study enzyme kinetics, transport of peptides into cells and the disposition of peptides within cells, tissues and organs. AAPPTec offers five fluorescein-based reagents for preparing labeled peptides, 5-FAM, 6-FAM, 5(6)-FAM, 5-FITC and 6-FITC. These reagents react with amines to form labeled compounds that fluoresce green when illuminated with UV light.





















Apex 396 HT Library Synthesizer

The Apex 396 HT is unsurpassed for high-throughput synthesis of peptide libraries. It synthesizes up to 192 different sequences at the same time using standard 1 mL well titer plates.

The Apex 396 HT is ideal for SAR studies. It can prepare complete alanine scan libraries, deletion libraries and truncation libraries to identify critical segments and residues. The library peptides are cleaved into standard 96 well titer plates.

SPPS Resins

AAPPTec provides the highest quality peptide synthesis resins at very competitive prices. All AAPPTec resins are examined microscopically to assure there are no broken, misshapen or undersize beads that can clog filters and interfere with peptide synthesis. The loading of AAPPTec resins are tested by two independent methods, assuring that the loading reported on the label is the loading you will observe during synthesis.

Rink amide resin, Merrifield resin, Wang resin, 2-chlorotrityl chloride resin and Sieber resin are a few of the high quality resins available from AAPPTec. In addition, AAPPTec offers preloaded Wang resins and preloaded 2-chlorotrityl resins.

AAPPTec resins are available in 100-200 mesh, 1% DVB crosslinked beads. Other bead sizes and crosslinkings are available upon request. For additional information about AAPPTec resin products, go to

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July 2015

Drug Discovery & Therapy World Congress

July 22-25
Boston, MA

29th Annual Symposium of the Protein Society

July 22-25
Barcelona, Spain

International Symposium on the Separation of Proteins, Peptides, and Polynucleotides

July 29-31
Philadelphia, PA