Extendable stapling of unprotected peptides by crosslinking two amines with o-phthalaldehyde

Peptide modification methods that do not rely on the cysteine residue are underdeveloped, and their development could greatly expand the current toolbox for peptide chemistry. During the course of preliminary investigations into the classical ortho-phthalaldehyde (OPA)-amine-thiol condensation reaction, we found that in the absence of thiol, OPA readily condenses with two primary alkyl amines to form a class of underexplored isoindolin-1-imine compounds under mild aqueous conditions. From the intramolecular version of this OPA-2amines reaction, an efficient and selective methodology using mild reaction conditions has been developed for stapling unprotected peptides via crosslinking of two amino groups in both an end-to-side and side-to-side fashion. The stapling method is superfast and broadly applicable for various peptide substrates with the reacting amino groups separated by a wide range of different amino acid units. The macrocyclization reactions of selected substrates are completed within 10 seconds at 5 mM concentration and within 2 minutes at 50 μM concentration. Importantly, the resulting cyclized peptides with an isoindolinimine linkage can be extended in a one-pot sequential addition manner with several different electron-deficient π electrophiles, thereby generating more complex structures.

Sustainability in peptide chemistry: current synthesis and purification technologies and future challenges

Developing greener synthetic processes is an inescapable necessity to transform the industrial landscape, mainly in the pharmaceutical sector, into a long-term, sustainable reality. In this context, the renaissance of peptides...

Flow-based Methods in Chemical Peptide and Protein Synthesis

Flow chemistry has emerged as a powerful method for on-demand chemical synthesis and modification of peptides and proteins. Herein, we discuss the characteristics of flow chemistry and how they are applied to various aspects of peptide chemistry. We highlight recent advances in automated flow-based peptide synthesis, which extend the length of peptides routinely accessible to single-domain proteins and allow for the collection of time-resolved synthesis data. Applications of this data for the prediction of synthesis outcome and the potential for the development of more sustainable synthesis methods are also discussed. Finally, we will review solutionphase approaches, including flow-based ligation strategies and peptide cyclization. Throughout this review, the current challenges and potential future developments are highlighted.

Uncovering Novel Peptide Chemistry from Bacterial Natural Products

Nature has evolved a remarkable array of biosynthetic enzymes that install diverse chemistries into natural products (NPs), bestowing them with a range of important biological properties that are of considerable therapeutic value. This is epitomized by the ribosomally synthesized and post-translationally modified peptides (RiPPs), a class of peptide natural products that undergo extensive post-translational modifications to produce structurally diverse bioactive peptides. In this review, we provide an overview of our research into the proteusin RiPP family, describing characterized members and the maturation enzymes responsible for their unique chemical structures and biological activities. The diverse enzymology identified in the first two proteusin pathways highlights the enormous potential of the RiPP class for new lead structures and novel pharmacophore-installing maturases as biocatalytic tools for drug discovery efforts.

Bachem – Insights into Innovative and Sustainable Peptide Chemistry and Technology by the Leading Independent Manufacturer of TIDES

Since its foundation in 1971, Bachem has grown sustainably over the last 50 years and is excellently positioned as the leading company for the development and production of TIDES i.e. peptides and oligonucleotides. Bachem's success relies on its commitment to manufacturing high-quality active pharmaceutical ingredients (APIs) alongside its continual passion for innovative chemistry and technologies. This review aims at summarizing improvements in high-quality peptide manufacturing as well as recent advances towards sustainable and innovative technology in peptide chemistry, thereby reducing the environmental footprint.

Amyloid-Like Aggregation in Diseases and Biomaterials: Osmosis of Structural Information

The discovery that the polypeptide chain has a remarkable and intrinsic propensity to form amyloid-like aggregates endowed with an extraordinary stability is one of the most relevant breakthroughs of the last decades in both protein/peptide chemistry and structural biology. This observation has fundamental implications, as the formation of these assemblies is systematically associated with the insurgence of severe neurodegenerative diseases. Although the ability of proteins to form aggregates rich in cross-β structure has been highlighted by recent studies of structural biology, the determination of the underlying atomic models has required immense efforts and inventiveness. Interestingly, the progressive molecular and structural characterization of these assemblies has opened new perspectives in apparently unrelated fields. Indeed, the self-assembling through the cross-β structure has been exploited to generate innovative biomaterials endowed with promising mechanical and spectroscopic properties. Therefore, this structural motif has become the fil rouge connecting these diversified research areas. In the present review, we report a chronological recapitulation, also performing a survey of the structural content of the Protein Data Bank, of the milestones achieved over the years in the characterization of cross-β assemblies involved in the insurgence of neurodegenerative diseases. A particular emphasis is given to the very recent successful elucidation of amyloid-like aggregates characterized by remarkable molecular and structural complexities. We also review the state of the art of the structural characterization of cross-β based biomaterials by highlighting the benefits of the osmosis of information between these two research areas. Finally, we underline the new promising perspectives that recent successful characterizations of disease-related amyloid-like assemblies can open in the biomaterial field.

Organic Chemistry for First Year Medical Students: Addressing the 'Grand Public'

Experiences from 20 years of teaching organic chemistry at the Medical School of the University of Geneva are recollected. Emphasis is on the question how to address a large audience without particular passion for chemistry. The key lesson learned is to offer a substantial justification for every topic right at the beginning, before the basics are covered. For instance, the course opens with vancomycin resistance, achieved by changing one functional group, even one atom into another, and introductory topics are then developed literally on the structure of a beautifully complex natural product (relation of molecules, functional groups and atoms, introduction of functional groups, the octet rule, hybridization, later on also peptide chemistry, stereochemistry, etc.). Tamiflu is launched right afterwards as a possible justification why medical students should learn reaction mechanisms, long before the concerned reaction, the transformation of an acetal into a hemiacetal, is discussed. Not all classical teaching topics are compatible with such ' relevance-triggered teaching ' (nomenclature certainly not, nor halogenoalkanes, aromatic substitutions, alkynes, most of alkenes, spectroscopy, etc.). Other topics deserve more attention, like the more complex cyclic structures of sugars and steroids in the structural part and carbonyl chemistry, including catalysis, as the center of the reactivity part of the course. Difficult to measure, such ' relevance-triggered ' course restructuring, inconceivable from a classical educational point of view, has been overall surprisingly well received, although definitely not by all students.