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 pep and oligonucleo. 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.

Natural Glycoforms of Human Interleukin 6 Show Atypical Plasma Clearance.

A library of glycoforms of human interleukin 6 (IL-6) comprising complex and mannosidic N-glycans was generated by semisynthesis. The three segments were connected by sequential native chemical ligation followed by two-step refolding. The central glycopeptide segments were assembled by pseudoproline-assisted Lansbury aspartylation and subsequent enzymatic elongation of complex N-glycans.

A Modular Ligation Strategy for Asymmetric Bivalent Nucleosomes Trimethylated at K36 and K27.

In nature, individual histones in the same nucleosome can carry identical (symmetric) or different (asymmetric) post-translational modification (PTM) patterns, increasing the combinatorial complexity. Embryonic stem cells exhibit "bivalent" nucleosomes, some of which are marked by an asymmetric arrangement of H3K36me3 (an activating PTM) and H3K27me3 (a repressive PTM). Here we describe a modular synthetic method to access such asymmetrically modified nucleosomes and show that H3K36me3 inhibits the activity of the methyltransferase PRC2 locally while still prolonging its chromatin binding time.

A bi-terminal protein ligation strategy to probe chromatin structure during DNA damage.

The cellular response to DNA damage results in a signaling cascade that primes chromatin for repair. Combinatorial post-translational modifications (PTMs) play an important role in this process by altering the physical properties of chromatin and recruiting downstream factors. One key signal integrator is the histone variant H2A.

Engineered Multivalent Sensors to Detect Coexisting Histone Modifications in Living Stem Cells.

The regulation of fundamental processes such as gene expression or cell differentiation involves chromatin states, demarcated by combinatorial histone post-translational modification (PTM) patterns. The subnuclear organization and dynamics of chromatin states is not well understood, as tools for their detection and modulation in live cells are lacking. Here, we report the development of genetically encoded chromatin-sensing multivalent probes, cMAPs, selective for bivalent chromatin, a PTM pattern associated with pluripotency in embryonic stem cells (ESCs).

Single-molecule kinetic analysis of HP1-chromatin binding reveals a dynamic network of histone modification and DNA interactions.

Chromatin recruitment of effector proteins involved in gene regulation depends on multivalent interaction with histone post-translational modifications (PTMs) and structural features of the chromatin fiber. Due to the complex interactions involved, it is currently not understood how effectors dynamically sample the chromatin landscape. Here, we dissect the dynamic chromatin interactions of a family of multivalent effectors, heterochromatin protein 1 (HP1) proteins, using single-molecule fluorescence imaging and computational modeling.

Controlling the supramolecular assembly of nucleosomes asymmetrically modified on H4.

In stem cells, H4 proteins carrying different modifications coexist within single nucleosomes. For functional studies, we report the synthesis of such asymmetric nucleosomes. Asymmetry is achieved by transiently crosslinking H4 by a traceless, protease-removable tag introduced via an isopeptide linkage.

Traceless Synthesis of Asymmetrically Modified Bivalent Nucleosomes.

Nucleosomes carry extensive post-translational modifications (PTMs), which results in complex modification patterns that are involved in epigenetic signaling. Although two copies of each histone coexist in a nucleosome, they may not carry the same PTMs and are often differently modified (asymmetric). In bivalent domains, a chromatin signature prevalent in embryonic stem cells (ESCs), namely H3 methylated at lysine 4 (H3K4me3), coexists with H3K27me3 in asymmetric nucleosomes.

Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation.

Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role.

Immobilising proteins on silica with site-specifically attached modified silaffin peptides.

Immobilisation of proteins on solid supports such as silica is commonly applied to improve performance of enzymes under detrimental conditions and to allow enzyme recycling. Silica biomineralisation processes occurring in nature have recently inspired approaches towards mild, biomimetic silica formation. In diatoms, complex posttranslationally modified silaffin peptides are directly involved in formation and patterning of silica cell walls.

Semisynthesis of biologically active glycoforms of the human cytokine interleukin 6.

Human interleukin 6 (IL-6) is a potent cytokine with immunomodulatory properties. As the influence of N-glycosylation on the in vivo activities of IL-6 could not be elucidated so far, a semisynthesis of homogeneous glycoforms of IL-6 was established by sequential native chemical ligation. The four cysteines of IL-6 are convenient for ligations and require only the short synthetic glycopeptide 43-48.

A sequence-function analysis of the silica precipitating silaffin R5 peptide.

The R5 peptide is derived from silaffin peptides naturally occurring in the diatom Cylindrotheca fusiformis and exhibits outstanding activity in silica precipitation. Because of its ability to cause silicification under mild conditions, several biotechnological applications based on R5-mediated biomimetic silica formation have already been reported. Yet a more detailed understanding of the R5 peptide and its intrinsic silica precipitation activity will help the rational design of R5 peptide variants as efficient agents for defined silica precipitation.

Modified silaffin R5 peptides enable encapsulation and release of cargo molecules from biomimetic silica particles.

Biomimetic silica formation has attracted increasing interest over the last decade for numerous biotechnological applications due to the favorable mild reaction conditions. Inspired from silica biogenesis in diatoms, peptide variants derived from native silaffins have been used for silica formation in vitro. Here a generally applicable route for covalently linking a cargo molecule to the R5 silaffin peptide via a disulfide linkage is established.