John M. Swan

Bio: John M. Swan is an academic researcher from Cooperative Research Centre. The author has contributed to research in topics: Isoglutamine & Peptide. The author has an hindex of 3, co-authored 3 publications receiving 466 citations.

Polymerization of Unprotected Synthetic Peptides: A View toward Synthetic Peptide Vaccines

Abstract: A generic method is reported for the assembly of multi-peptide polymers in which peptides are synthesized in the solid phase, the N-terminal residue acryloylated, and the derivitized peptides cleaved, purified and finally polymerized by free radical induced polymerization. The high molecular weight polymers generated in this way have individual peptides pendant from a backbone support. Incorporation of 6-aminohexanoyl or other residue(s) at the N-terminus of the peptide prior to acryloylation allows the peptide to be distanced from the polymer backbone and incorporation of acryloylated reagents into the polymerization mixture also permits distancing of pendant peptides along the length of the backbone support. The polymerization process results in highly antigenic artificial proteins as measured by ELISA. Because this approach allows the incorporation of the same or combinations of different purified peptides into polymers, it lends itself to the assembly of potential vaccine candidates containing epitopes from single or multiple pathogens into a single covalent structure.

Sequence-controlled polymers.

Abstract: Background During the last few decades, progress has been made in manipulating the architecture of synthetic polymer materials. However, the primary structure—that is, the sequential arrangement of monomer units in a polymer chain—is generally poorly controlled in synthetic macromolecules. Common synthetic polymers are usually homopolymers, made of the same monomer unit, or copolymers with simple chain microstructures, such as random or block copolymers. These polymers are used in many areas but do not have the structural and functional complexity of sequence-defined biopolymers, such as nucleic acids or proteins. Indeed, monomer sequence regulation plays a key role in biology and is a prerequisite for crucial features of life, such as heredity, self-replication, complex self-assembly, and molecular recognition. In this context, developing synthetic polymers containing controlled monomer sequences is an important area for research. Precise molecular encoding of synthetic polymer chains. In most synthetic copolymers, monomer units (represented here as colored square boxes A, B, C, and D) are distributed randomly along the polymer chains (left). In sequence-controlled polymers, they are arranged in a specific order in all of the chains (right). Monomer sequence regularity strongly influences the molecular, supramolecular, andmacroscopic properties of polymer materials. Advances Various synthetic methods for controlling monomer sequences in polymers have been identified, and two major trends in the field of sequence-controlled polymers have emerged. Some approaches use biological concepts that have been optimized by nature for sequence regulation. For instance, DNA templates, enzymes, or even living organisms can be used to prepare sequence-defined polymers. These natural mechanisms can be adapted to tolerate nonnatural monomers. The other trend is the preparation of sequence-controlled polymers by synthetic chemistry. In the most popular approach, monomer units are attached one by one to a support, which is an efficient method but demanding in practice. Recently, some strategies have been proposed for controlling sequences in chain-growth and step-growth polymerizations. These mechanisms usually allow fast and large-scale synthesis of polymers. Specific kinetics and particular catalytic or template conditions allow sequence regulation in these processes. Outlook The possibility of controlling monomer sequences in synthetic macromolecules has many scientific and technological implications. Information can be controlled at the molecular level in synthetic polymer chains. This opens up interesting perspectives for the field of data storage. In addition, having power over monomer sequences could mean structural control of the resulting polymer, as it strongly influences macromolecular folding and self-assembly. For instance, functional synthetic assemblies that mimic the properties of globular proteins, such as enzymes and transporters, can be foreseen. Moreover, monomer sequence control influences some macroscopic properties. For example, bulk properties such as conductivity, rigidity, elasticity, or biodegradability can be finely tuned in sequence-controlled polymers. The behavior of polymers in solution, particularly in water, is also strongly dependent on monomer sequences. Thus, sequence regulation may enable a more effective control of structure-property relations in tomorrow’s polymer materials.

Experimental and theoretical aspects of protein folding.

Abstract: Publisher Summary In the proper environment, a polypeptide chain can fold spontaneously to the three-dimensional structure of a native protein, and despite the possible presence of barriers in conformational space, the chain can find its way around these barriers to reach the structure of lowest free energy. This chapter describes the spontaneous folding of proteins; in vitro complementation of protein fragments; flexibility of proteins in solution: effect of cross-links and ligands, synthetic analogs of proteins; experimental approaches to the study of conformation; and energetic factors determining protein folding. The interatomic interactions within the chain and between the chain and the solvent dictate the folding and the range of the forces involved, is such that near-neighbor interactions are dominant. Folding is envisaged as taking place by the formation of nucleation sites in various parts of the chain, in response to near-neighbor interactions; the various nucleation sites become stabilized, when they are brought into proximity, so that long-range interactions can become operative. However, the development of conformational energy calculation procedures will enable the three-dimensional structure of a native protein to be predicted from the knowledge of its amino acid sequence and its interactions with the solvent in which it is dissolved.

The Current State of Peptide Drug Discovery: Back to the Future?

Abstract: Over the past decade, peptide drug discovery has experienced a revival of interest and scientific momentum, as the pharmaceutical industry has come to appreciate the role that peptide therapeutics can play in addressing unmet medical needs and how this class of compounds can be an excellent complement or even preferable alternative to small molecule and biological therapeutics. In this Perspective, we give a concise description of the recent progress in peptide drug discovery in a holistic manner, highlighting enabling technological advances affecting nearly every aspect of this field: from lead discovery, to synthesis and optimization, to peptide drug delivery. An emphasis is placed on describing research efforts to overcome the inherent weaknesses of peptide drugs, in particular their poor pharmacokinetic properties, and how these efforts have been critical to the discovery, design, and subsequent development of novel therapeutics.

The Oxytocin Receptor: From Intracellular Signaling to Behavior

Abstract: The many facets of the oxytocin (OXT) system of the brain and periphery elicited nearly 25,000 publications since 1930 (see FIGURE 1, as listed in PubMed), which revealed central roles for OXT and ...