A naturally occurring 22-amino acid fragment of human hemoglobin A inhibits autophagy and HIV-1.

Autophagy is an evolutionarily ancient catabolic pathway and has recently emerged as an integral part of the innate immune system. While the core machinery of autophagy is well defined, the physiological regulation of autophagy is less understood. Here, we identify a C-terminal fragment of human hemoglobin A (HBA1, amino acids 111-132) in human bone marrow as a fast-acting non-inflammatory inhibitor of autophagy initiation.

Ion and Molecular Sieving With Ultrathin Polydopamine Nanomembranes.

In contrast to biological cell membranes, it is still a major challenge for synthetic membranes to efficiently separate ions and small molecules due to their similar sizes in the sub-nanometer range. Inspired by biological ion channels with their unique channel wall chemistry that facilitates ion sieving by ion-channel interactions, the first free-standing, ultrathin (10-17 nm) nanomembranes composed entirely of polydopamine (PDA) are reported here as ion and molecular sieves. These nanomembranes are obtained via an easily scalable electropolymerization strategy and provide nanochannels with various amine and phenolic hydroxyl groups that offer a favorable chemical environment for ion-channel electrostatic and hydrogen bond interactions.

Macrocyclic Dual-Locked "Turn-On" Drug for Selective and Traceless Release in Cancer Cells.

Drug safety and efficacy due to premature release into the bloodstream and poor biodistribution remains a problem despite seminal advances in this area. To circumvent these limitations, we report drug cyclization based on dynamic covalent linkages to devise a dual lock for the small-molecule anticancer drug, camptothecin (CPT). Drug activity is "locked" within the cyclic structure by the redox responsive disulfide and pH-responsive boronic acid-salicylhydroxamate and turns on only in the presence of acidic pH, reactive oxygen species and glutathione through traceless release.

Peptide Bispecifics Inhibiting HIV-1 Infection by an Orthogonal Chemical and Supramolecular Strategy.

Viral infections pose a significant threat to human health, and effective antiviral strategies are urgently needed. Antiviral peptides have emerged as a promising class of therapeutic agents due to their unique properties and mechanisms of action. While effective on their own, combining antiviral peptides may allow us to enhance their potency and to prevent viral resistance.

Subnanomolar Cathepsin S Inhibitors with High Selectivity: Optimizing Covalent Reversible α-Fluorovinylsulfones and α-Sulfonates as Potential Immunomodulators in Cancer.

The cysteine protease cathepsin S (CatS) is overexpressed in many tumors. It is known to be involved in tumor progression as well as antigen processing in antigen-presenting cells (APC). Recent evidence suggests that silencing CatS improves the anti-tumor immune response in several cancers.

Advanced EPI-X4 Derivatives Covalently Bind Human Serum Albumin Resulting in Prolonged Plasma Stability.

Advanced derivatives of the ndogenous eptide nhibitor of CCR (EPI-X4) have shown therapeutic efficacy upon topical administration in animal models of asthma and dermatitis. Here, we studied the plasma stability of the EPI-X4 lead compounds WSC02 and JM#21, using mass spectrometry to monitor the chemical integrity of the peptides and a functional fluorescence-based assay to determine peptide function in a CXCR4-antibody competition assay. Although mass spectrometry revealed very rapid disappearance of both peptides in human plasma within seconds, the functional assay revealed a significantly higher half-life of 9 min for EPI-X4 WSC02 and 6 min for EPI-X4 JM#21.

Assembly of pH-Responsive Antibody-Drug-Inspired Conjugates.

With the advent of chemical strategies that allow the design of smart bioconjugates, peptide- and protein-drug conjugates are emerging as highly efficient therapeutics to overcome limitations of conventional treatment, as exemplified by antibody-drug conjugates (ADCs). While targeting peptides serve similar roles as antibodies to recognize overexpressed receptors on diseased cell surfaces, peptide-drug conjugates suffer from poor stability and bioavailability due to their low molecular weights. Through a combination of a supramolecular protein-based assembly platform and a pH-responsive linker, the authors devise herein the convenient assembly of a trivalent protein-drug conjugate.

Chemoselective cysteine or disulfide modification single atom substitution in chloromethyl acryl reagents.

The development of bioconjugation chemistry has enabled the combination of various synthetic functionalities to proteins, giving rise to new classes of protein conjugates with functions well beyond what Nature can provide. Despite the progress in bioconjugation chemistry, there are no reagents developed to date where the reactivity can be tuned in a user-defined fashion to address different amino acid residues in proteins. Here, we report that 2-chloromethyl acryl reagents can serve as a simple yet versatile platform for selective protein modification at cysteine or disulfide sites by tuning their inherent electronic properties through the amide or ester linkage.

Dual Stimuli-Responsive Dynamic Covalent Peptide Tags: Toward Sequence-Controlled Release in Tumor-like Microenvironments.

Dynamic covalent chemistry (DCvC) has emerged as a versatile synthetic tool for devising stable, stimuli-responsive linkers or conjugates. The interplay of binding affinity, association and dissociation constants exhibits a strong influence on the selectivity of the reaction, the conversion rate, as well as the stability in aqueous solutions. Nevertheless, dynamic covalent interactions often exhibit fast binding and fast dissociation events or vice versa, affecting their conversion rates or stabilities.

Contemporary Approaches for Site-Selective Dual Functionalization of Proteins.

Site-selective protein functionalization serves as an invaluable tool for investigating protein structures and functions in complicated cellular environments and accomplishing semi-synthetic protein conjugates such as traceable therapeutics with improved features. Dual functionalization of proteins allows the incorporation of two different types of functionalities at distinct location(s), which greatly expands the features of native proteins. The attachment and crosstalk of a fluorescence donor and an acceptor dye provides fundamental insights into the folding and structural changes of proteins upon ligand binding in their native cellular environments.

Precise tetrafunctional streptavidin bioconjugates towards multifaceted drug delivery systems.

The preparation of precise macromolecules with multiple functionalities remains a challenge in drug delivery. Here, a method to prepare stoichiometrically precise tetrafunctional streptavidin conjugates is presented with an exemplary structure combining exactly one fluorescent label, one cell targeting group, one nucleus penetrating peptide and one drug molecule.

Solid-Phase Protein Modifications: Towards Precision Protein Hybrids for Biological Applications.

Proteins have attracted increasing attention as biopharmaceutics and diagnostics due to their high specificity, biocompatibility, and biodegradability. The biopharmaceutical sector in particular is experiencing rapid growth, which has led to an increase in the production and sale of protein drugs and diagnostics over the last two decades. Since the first-generation biopharmaceutics dominated by native proteins, both recombinant and chemical technologies have evolved and transformed the outlook of this rapidly developing field.

Site-selective protein modification via disulfide rebridging for fast tetrazine/trans-cyclooctene bioconjugation.

An inverse electron demand Diels-Alder reaction between tetrazine and trans-cyclooctene (TCO) holds great promise for protein modification and manipulation. Herein, we report the design and synthesis of a tetrazine-based disulfide rebridging reagent, which allows the site-selective installation of a tetrazine group into disulfide-containing peptides and proteins such as the hormone somatostatin (SST) and the antigen binding fragment (Fab) of human immunoglobulin G (IgG). The fast and efficient conjugation of the tetrazine modified proteins with three different TCO-containing substrates to form a set of bioconjugates in a site-selective manner was successfully demonstrated for the first time.

Somatostatin receptor mediated targeting of acute myeloid leukemia by photodynamic metal complexes for light induced apoptosis.

Acute myeloid leukemia (AML) is characterized by relapse and treatment resistance in a major fraction of patients, underlining the need of innovative AML targeting therapies. Here we analysed the therapeutic potential of an innovative biohybrid consisting of the tumor-associated peptide somatostatin and the photosensitizer ruthenium in AML cell lines and primary AML patient samples. Selective toxicity was analyzed by using CD34 enriched cord blood cells as control.

Patchy Amphiphilic Dendrimers Bind Adenovirus and Control Its Host Interactions and in Vivo Distribution.

The surface of proteins is heterogeneous with sophisticated but precise hydrophobic and hydrophilic patches, which is essential for their diverse biological functions. To emulate such distinct surface patterns on macromolecules, we used rigid spherical synthetic dendrimers (polyphenylene dendrimers) to provide controlled amphiphilic surface patches with molecular precision. We identified an optimal spatial arrangement of these patches on certain dendrimers that enabled their interaction with human adenovirus 5 (Ad5).

Supramolecular Toxin Complexes for Targeted Pharmacological Modulation of Polymorphonuclear Leukocyte Functions.

The targeted pharmacological modulation of polymorphonuclear leukocytes (PMNs) is of major medical interest. These innate immune cells play a central role in the defense against pathogenic microorganisms. However, their excessive chemotactic recruitment into tissues after traumatic injury is detrimental due to local and systemic inflammation.

Functional protein nanostructures: a chemical toolbox.

Nature has evolved an optimal synthetic factory in the form of translational and posttranslational processes by which millions of proteins with defined primary sequences and 3D structures can be built. Nature's toolkit gives rise to protein building blocks, which dictates their spatial arrangement to form functional protein nanostructures that serve a myriad of functions in cells, ranging from biocatalysis, formation of structural networks, and regulation of biochemical processes, to sensing. With the advent of chemical tools for site-selective protein modifications and recombinant engineering, there is a rapid development to develop and apply synthetic methods for creating structurally defined, functional protein nanostructures for a broad range of applications in the fields of catalysis, materials and biomedical sciences.

Boosting Antitumor Drug Efficacy with Chemically Engineered Multidomain Proteins.

A facile chemical approach integrating supramolecular chemistry, site-selective protein chemistry, and molecular biology is described to engineer synthetic multidomain protein therapeutics that sensitize cancer cells selectively to significantly enhance antitumor efficacy of existing chemotherapeutics. The desired bioactive entities are assembled via supramolecular interactions at the nanoscale into structurally ordered multiprotein complexes comprising a) multiple copies of the chemically modified cyclic peptide hormone somatostatin for selective targeting and internalization into human A549 lung cancer cells expressing SST-2 receptors and b) a new cysteine mutant of the C3bot1 (C3) enzyme from , a Rho protein inhibitor that affects and influences intracellular Rho-mediated processes like endothelial cell migration and blood vessel formation. The multidomain protein complex, SST3-Avi-C3, retargets C3 enzyme into non-small cell lung A549 cancer cells and exhibits exceptional tumor inhibition at a concentration ≈100-fold lower than the clinically approved antibody bevacizumab (Avastin) in vivo.

Antimicrobial and Anti-Biofilm Activities of Surface Engineered Polycationic Albumin Nanoparticles with Reduced Hemolytic Activity.

Protein-based polymeric polyelectrolytes are emerging as alternative synthetic nanoparticles owing to their biodegradability and biocompatibility. However, potential in vivo toxicity remains a significant challenge. Herein an array of protein polyelectrolytes generated from cationic human serum albumin (cHSA) and polyethylene glycol (PEG) are synthesized via synthetic customization as antimicrobials for the treatment of systemic infections.

Dynamic Core-Shell Bioconjugates for Targeted Protein Delivery and Release.

Dynamic covalent chemistry is a versatile and powerful tool that integrates both stable chemical bonds and stimulus responsiveness into the construction of smart biotherapeutics. With minimalistic molecular design, a dynamic covalent protein assembly that incorporates selective targeting and intracellular release upon pH stimulus is presented. The construct comprises an active enzymatic protein core (cytochrome c) self-assembled with cancer cell targeting motifs (somatostatin) through boronic acid/salicylhydroxamate chemistry.

"Tag and Modify" Protein Conjugation with Dynamic Covalent Chemistry.

The development of small protein tags that exhibit bioorthogonality, bond stability, and reversibility, as well as biocompatibility, holds great promise for applications in cellular environments enabling controlled drug delivery or for the construction of dynamic protein complexes in biological environments. Herein, we report the first application of dynamic covalent chemistry both for purification and for reversible assembly of protein conjugates using interactions of boronic acid with diols and salicylhydroxamates. Incorporation of the boronic acid (BA) tag was performed in a site-selective fashion by applying disulfide rebridging strategy.

Engineering Proteins at Interfaces: From Complementary Characterization to Material Surfaces with Designed Functions.

Once materials come into contact with a biological fluid containing proteins, proteins are generally-whether desired or not-attracted by the material's surface and adsorb onto it. The aim of this Review is to give an overview of the most commonly used characterization methods employed to gain a better understanding of the adsorption processes on either planar or curved surfaces. We continue to illustrate the benefit of combining different methods to different surface geometries of the material.

Chemoselective Dual Labeling of Native and Recombinant Proteins.

The attachment of two different functionalities in a site-selective fashion represents a great challenge in protein chemistry. We report site specific dual functionalizations of peptides and proteins capitalizing on reactivity differences of cysteines in their free (thiol) and protected, oxidized (disulfide) forms. The dual functionalization of interleukin 2 and EYFP proceeded with no loss of bioactivity in a stepwise fashion applying maleimide and disulfide rebridging allyl-sulfone groups.

Spatiotemporally Controlled Release of Rho-Inhibiting C3 Toxin from a Protein-DNA Hybrid Hydrogel for Targeted Inhibition of Osteoclast Formation and Activity.

In osteoporosis, bone structure can be improved by the introduction of therapeutic molecules inhibiting bone resorption by osteoclasts. Here, biocompatible hydrogels represent an excellent option for the delivery of pharmacologically active molecules to the bone tissue because of their biodegradability, injectability, and manifold functionalization capacity. The present study reports the preparation of a multifunctional hybrid hydrogel from chemically modified human serum albumin and rationally designed DNA building blocks.