1,2,3-Triazoles as Biomimetics in Peptide Science

Natural peptides are an important class of chemical mediators, essential for most vital processes. What limits the potential of the use of peptides as drugs is their low bioavailability and enzymatic degradation in vivo. To overcome this limitation, the development of new molecules mimicking peptides is of great importance for the development of new biologically active molecules. Therefore, replacing the amide bond in a peptide with a heterocyclic bioisostere, such as the 1,2,3-triazole ring, can be considered an effective solution for the synthesis of biologically relevant peptidomimetics. These 1,2,3-triazoles may have an interesting biological activity, because they behave as rigid link units, which can mimic the electronic properties of amide bonds and show bioisosteric effects. Additionally, triazole can be used as a linker moiety to link peptides to other functional groups.

Recovery, Purification, and Reusability of Building Blocks for Solid Phase Synthesis

Solid phase synthesis (SPS) is well established for the synthesis of biomacromolecules such as peptides, oligonucelotides, and oligosaccharides, and today is also used for the synthesis of synthetic macromolecules and polymers. The key feature of this approach is the stepwise assembly of building blocks on solid support, enabling monodispersity and monomer sequence control. However, in order to achieve such control, a high excess of building blocks is required during the reaction. Herein, the recovery, purification, and reusability of building blocks used in SPS, including representative examples of tailor-made building blocks, Fmoc-protected amino acids, and functionalized carbohydrate ligands, are reported for the first time. Results demonstrate the general applicability with recovery in high yields and high purity. Furthermore, the described recovery process can be applied in both manual and automated synthesis using a standard peptide synthesizer. Overall, this process is envisioned to be applicable for a large variety of building blocks used in the SPS of different types of molecules, and to contribute to more resourceful SPS syntheses.

Design and synthesis of galactose-conjugated fluorinated and non-fluorinated proline oligomers: towards antifreeze molecules

Galactose-conjugated fluorinated and non-fluorinated proline oligomers that exhibit an α-helical structure with hydrophilic and lipophilic parts were designed as potential antifreeze molecules. These galactose-proline oligomers were synthesized and their physical properties were evaluated. Interestingly, the non-fluorinated galactose-proline oligomers showed in contrast to the fluorinated analogues weak antifreeze activity. The difference in antifreeze activity should be attributed to the fluorine gauche effect, which should induce a conformation in fluorinated prolines that is different from that of natural proline. The results obtained in this study thus suggest that the 3D conformation of the galactose-conjugated fluorinated and non-fluorinated proline oligomers is very important for their anti-freezing properties.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.

Cu Elimination from Cu-Coordinating Macromolecules

We demonstrate a simple, fast, and efficient process for the elimination of Cu impurities from water-soluble Cu-coordinating macromolecules that are difficult to purify via standard polymer purification techniques. The process is based on the complexation and precipitation of Cu by sodium diethyldithiocarbamate and was investigated for two different compound classes known to coordinate to Cu in aqueous solution. More than 99.9% of the Cu impurity was eliminated, with a remaining level below the detection limit (0.0005 wt %). Further analysis by ¹H NMR, MALDI, ATR-IR, and SEC showed no degradation or side reactions of the polymers induced by the treatment. This process thus compliments the growing toolbox of Cu-catalyzed conjugation techniques as a mild, effective, and scalable tool for the removal of Cu from water-soluble and Cu-coordinating polymers.

Antifreeze glycopeptides: from structure and activity studies to current approaches in chemical synthesis

Antifreeze glycopeptides (AFGPs) are a class of biological antifreeze agents found predominantly in Arctic and Antarctic species of fish. They possess the ability to regulate ice nucleation and ice crystal growth, thus creating viable life conditions at temperatures below the freezing point of body fluids. AFGPs usually consist of 4–55 repetitions of the tripeptide unit Ala–Ala–Thr that is O-glycosylated at the threonine side chains with β-d-galactosyl-(1 → 3)-α-N-acetyl-d-galactosamine. Due to their interesting properties and high antifreeze activity, they have many potential applications, e.g., in food industry and medicine. Current research is focused towards understanding the relationship between the structural preferences and the activity of the AFGPs, as well as developing time and cost efficient ways of synthesis of this class of molecules. Recent computational studies in conjunction with experimental results from NMR and THz spectroscopies were a possible breakthrough in understanding the mechanism of action of AFGPs. At the moment, as a result of these findings, the focus of research is shifted towards the analysis of behaviour of the hydration shell around AFGPs and the impact of water-dynamics retardation caused by AFGPs on ice crystal growth. In the field of organic synthesis of AFGP analogues, most of the novel protocols are centered around solid-phase peptide synthesis and multiple efforts are made to optimize this approach. In this review, we present the current state of knowledge regarding the structure and activity of AFGPs, as well as approaches to organic synthesis of these molecules with focus on the most recent developments.

Biodegradable poly(amidoamine)s with uniform degradation fragments via sequence-controlled macromonomers

This work presents the translation of sequence-controlled synthesis of macromonomers into sequence-defined and selectively degradable precision polymers.

Designing ice recrystallization inhibitors: from antifreeze (glyco)proteins to small molecules

Ice recrystallization occurs during cryopreservation and is correlated with reduced cell viability after thawing.