Peptide-Based Supramolecular Systems Chemistry.

Peptide-based supramolecular systems chemistry seeks to mimic the ability of life forms to use conserved sets of building blocks and chemical reactions to achieve a bewildering array of functions. Building on the design principles for short peptide-based nanomaterials with properties, such as self-assembly, recognition, catalysis, and actuation, are increasingly available. Peptide-based supramolecular systems chemistry is starting to address the far greater challenge of systems-level design to access complex functions that emerge when multiple reactions and interactions are coordinated and integrated. We discuss key features relevant to systems-level design, including regulating supramolecular order and disorder, development of active and adaptive systems by considering kinetic and thermodynamic design aspects and combinatorial dynamic covalent and noncovalent interactions. Finally, we discuss how structural and dynamic design concepts, including preorganization and induced fit, are critical to the ability to develop adaptive materials with adaptive and tunable photonic, electronic, and catalytic properties. Finally, we highlight examples where multiple features are combined, resulting in chemical systems and materials that display adaptive properties that cannot be achieved without this level of integration.

Expanding the Conformational Landscape of Minimalistic Tripeptides by Their O-Glycosylation.

We report on the supramolecular self-assembly of tripeptides and their O-glycosylated analogues, in which the carbohydrate moiety is coupled to a central serine or threonine flanked by phenylalanine residues. The substitution of serine with threonine introduces differential side-chain interactions, which results in the formation of aggregates with different morphology. O-glycosylation decreases the aggregation propensity because of rebalancing of the π interactions. The glycopeptides form aggregates with reduced stiffness but increased thermal stability. Our results demonstrate that the designed minimalistic glycopeptides retain critical functional features of glycoproteins and therefore are promising tools for elucidation of molecular mechanisms involved in the glycoprotein interactome. They can also serve as an inspiration for the design of functional glycopeptide-based biomaterials.

A stable bacterial peroxidase with novel halogenating activity and an autocatalytically linked heme prosthetic group.

Reconstructing the phylogenetic relationships of the main evolutionary lines of the mammalian peroxidases lactoperoxidase and myeloperoxidase revealed the presence of novel bacterial heme peroxidase subfamilies. Here, for the first time, an ancestral bacterial heme peroxidase is shown to possess a very high bromide oxidation activity (besides conventional peroxidase activity). The recombinant protein allowed monitoring of the autocatalytic peroxide-driven formation of covalent heme to protein bonds. Thereby, the high spin ferric rhombic heme spectrum became similar to lactoperoxidase, the standard reduction potential of the Fe(III)/Fe(II) couple shifted to more positive values (-145 ± 10 mV at pH 7), and the conformational and thermal stability of the protein increased significantly. We discuss structure-function relationships of this new peroxidase in relation to its mammalian counterparts and ask for its putative physiological role.