Knud J. Jensen

Knud J. Jensen
University of Copenhagen · Department of Chemistry

PhD

About

279
Publications
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Publications

Publications (279)
Article
Abstract The chemical modification of proteins is of great importance in chemical biology, biotechnology, and for the production of modified biopharmaceuticals, as it enables introduction of fluorophores, biotin, half‐life extending moieties, and more. We developed two methods for using poly‐His sequences to direct the highly selective acylation of...
Preprint
Insulin formulations are the hallmark of interventions for treatment of diabetes. Understanding the mechanism that governs insulin self assembly or disassembly, and the role of stabilizing additives, are essential for improving insulin formulations. We report here the real-time direct observation of single insulin self-assembly and disassembly even...
Article
Full-text available
Somatostatin and its related peptides (SSRPs) form an important family of hormones with diverse physiological roles. The ubiquitous presence of SSRPs in vertebrates and several invertebrate deuterostomes suggests an ancient origin of the SSRP signaling system. However, the existence of SSRP genes outside of deuterostomes has not been established, a...
Article
Chemical modification of proteins has numerous applications, but it has been challenging to achieve the required high degree of selectivity on lysine amino groups. Recently, we described the highly selective acylation of proteins with an N‐terminal Gly‐His 6 segment. This tag promoted acylation of the N‐terminal N α ‐amine resulting in stable conju...
Article
Human insulin (HI) has fascinating metal-facilitated self-assembly properties that are essential for its biological function. HI has a natural Zn²⁺ binding site and we have previously shown that covalently attached abiotic ligands (e.g., bipyridine, terpyridine) can lead to the formation of nanosized oligomeric structures through the coordination o...
Article
Full-text available
Chiral communications exist in secondary structures of foldamers and copolymers via a network of noncovalent interactions within effective intermolecular force (IMF) range. It is not known whether long-range chiral communication exists between macromolecular tertiary structures such as peptide coiled-coils beyond the IMF distance. Harnessing the hi...
Preprint
Somatostatin and its related peptides (SSRPs) form a family of hormones with diverse physiological roles. The ubiquitous presence of SSRPs in vertebrates and several invertebrate deuterostomes suggests an ancient origin of the SSRP signaling system. However, the existence of SSRP genes outside of deuterostomes has not been established and the evolu...
Article
Full-text available
Significance Plant cell surface receptors perceive carbohydrate signaling molecules and hereby establish communication with surrounding microbes. Genetic studies have identified two different classes of lysin motif receptor kinases as gatekeepers that together trigger the symbiotic pathway in plants; however, no structural or functional data of the...
Article
Full-text available
Plant metabolism depends on cascade reactions mediated by dynamic enzyme assemblies known as metabolons. In this context, the cytochrome P450 (P450) superfamily catalyze key reactions underpinning the unique diversity of bioactive compounds. In contrast to their soluble bacterial counterparts, eukaryotic P450s are anchored to the endoplasmic reticu...
Article
The use of C-terminal peptide thioesters and hydrazides in synthetic protein chemistry has inspired the search for optimal solid-phase peptide synthesis (SPPS) strategies for their assembly. However, peptide thioesters are not directly accessible by conventional Fmoc-SPPS owing to the nucleophilicity of the secondary amine required for Fmoc removal...
Article
Full-text available
Glioblastoma (GBM) is a devastating cancer with basically no curative treatment. Even with aggressive treatment, the median survival is disappointing 14 months. Surgery remains the key treatment and the postoperative survival is determined by the extent of resection. Unfortunately, the invasive growth with irregular infiltrating margins complicates...
Article
Metal ion-induced self-assembly (SA) of proteins into higher-order structures can provide new, dynamic nano-assemblies. Here, the synthesis and characterization of a human insulin (HI) analog modified at LysB29 with the tridentate chelator 2,2':6',2''-terpyridine (Tpy) is described. SA of this new insulin analog (LysB29Tpy-HI) in the presence of th...
Article
Stimuli‐responsive lipids based on a glucose head group could promote pore formation in the membrane of liposomes upon treatment with EDTA. Using a total internal reflection fluorescence (TIRF) microscopy setup, it was possible to monitor the release of a fluorescent dye from liposomes containing the metal chelator‐responsive lipids. The liposomes...
Article
Preparative reversed‐phase HPLC is the established method for purification of peptides, but has significant limitations. We systematically investigated the use of high‐performance reversed‐phase flash chromatography (HPFC) to rapidly purify laboratory‐scale quantities of crude, synthetic peptides and chemically modified insulins. We demonstrated th...
Article
Liposomes are versatile three‐dimensional, biomaterial based frameworks that can spatially enclose a variety of organic and inorganic biomaterial for advanced targeted delivery applications. Implementation of external stimuli controlled release of their cargo will significantly augment their wide application for liposomal drug delivery. In this pap...
Article
Attachment of cationic moieties onto oligonucleotides (ONs) promises not only to increase the binding affinity of antisense ONs by reducing charge repulsion between the two negative strands of a duplex but also to augment their in vivo stability against nucleases. In this study, polyamine functionalities were introduced into ONs via 2’‐amino‐LNA sc...
Article
Switching perception of friend and foe Lysine motif receptors in plants perceive glycans that signal the presence of pathogenic or symbiotic nitrogen-fixing microbes. Bozsoki et al. now define the portions of these receptors that create the discriminatory binding pocket (see the Perspective by Bisseling and Geurts). The motifs were conserved in rec...
Article
Controlled self-assembly of peptide- and protein-based pharmaceuticals is of central importance for their mode of action and tuning of their properties. Peptide YY 3-36 (PYY 3-36 ) is a 36 amino acid peptide hormone that reduces food intake when peripherally administered. Herein, we describe the synthesis of a PYY 3-36 analogue functionalized with...
Article
Insulin is a fascinating small protein that is accessible to synthetic organic chemistry. It is amenable to a wide range of chemical reactions, such as acylations, reductive alkylations, reduction, and binding of different metal ions, which can modify it properties. Insulin is also a very important biopharmaceutical and chemically modified insulin...
Article
Biological membranes have distinct geometries that confer specific functions. However, the molecular mechanisms underlying the phenomenological geometry/function correlations remain elusive. We studied the effect of membrane geometry on the localization of membrane-bound proteins. Quantitative comparative experiments between the two most abundant c...
Article
Insulin is a small protein crucial for regulating the blood glucose level in all animals. Since 1922 it has been used for the treatment of patients with diabetes. Despite consisting of just 51 amino acids, insulin contains 17 of the proteinogenic amino acids, A‐ and B‐chains, three disulfide bridges, and it folds with 3 a‐helices and a short b‐shee...
Article
DNA nanostructures have been designed and used in many different applications. However, the use of nucleic acid scaffolds to promote the self‐assembly of artificial protein mimics is only starting to emerge. Herein five coiled‐coil peptide structures were templated by the hybridization of a D‐DNA triplex or its mirror‐image counterpart, an L‐DNA tr...
Article
Oligomers assembled from designed building blocks to fold in novel ways have emerged as tools and allow the creation of new structures and molecular properties. Here we describe the use of a highly constrained adamantane moiety with one amino group and three carboxylic acids as a monomer. It can be viewed as a constrained, α,α‐dialkylated γ‐amino t...
Article
Inhaled antibiotic treatment of cystic fibrosis (CF)-related bacterial biofilm infections is challenging due to the pathological environment of the lungs. Here, we present an ‘environment adaptive’ nanoparticle composed of a solid poly lactic-co-glycolic acid (PLGA) core and a mucus-inert, enzymatically cleavable shell of d-α-tocopheryl polyethylen...
Article
Peptide YY3-36 (PYY3-36) is an endogenous ligand of the neuropeptide Y2 receptor (Y2R), on which it acts to reduce food intake. Chemically modified PYY3-36 analogs with extended half-lives are potential therapeutics for the treatment of obesity. Here we show that the common half-life extending strategies PEGylation and lipidation not only control P...
Article
Polyglutamine diseases are a set of progressive neurodegenerative disorders caused by misfolding and aggregation of mutant CAG RNA and polyglutamin protein. To date, there is a lack of effective therapeutic that can counteract the polyglutamine neurotoxicity. Two peptidylic inhibitors, QBP1 and P3, targeting the protein and RNA toxicities respectiv...
Article
Full-text available
Morphogens provide positional information and their concentration is key to the organized development of multicellular organisms. Nitrogen-fixing root nodules are unique organs induced by Nod factor-producing bacteria. Localized production of Nod factors establishes a developmental field within the root where plant cells are reprogrammed to form in...
Article
Full-text available
Methods for site-selective chemistry on proteins are in high demand for the synthesis of chemically modified biopharmaceuticals, as well as for applications in chemical biology, biosensors and more. Inadvertent N-terminal gluconoylation has been reported during expression of proteins with an N-terminal His tag. Here we report the development of thi...
Article
Full-text available
Recognition of Nod factors by LysM receptors is crucial for nitrogen-fixing symbiosis in most legumes. The large families of LysM receptors in legumes suggest concerted functions, yet only NFR1 and NFR5 and their closest homologs are known to be required. Here we show that an epidermal LysM receptor (NFRe), ensures robust signalling in L. japonicus...
Data
Differentially expressed genes in the susceptible zone of wild-type and nfre mutant roots after Nod factor treatment.
Data
Signalling from NFRe in Lotus roots is dependent of NFR5.
Article
Full-text available
Strategies for half-life extension are often required in the design of new biopharmaceuticals. This Viewpoint focuses on chemical moieties that convey protraction by albumin binding or by self-assembly to form larger structures, with GLP-1 and insulin as examples.
Article
Two highly specific biomolecular recognition events, nucleic acid duplex hybridization and DNA-peptide recognition in the minor groove, were coalesced in a miniature ensemble for the first time by covalently attaching a natural AT-hook peptide motif to nucleic acid duplexes via a 2ʹ-amino-LNA scaffold. A combination of molecular dynamics simulation...
Article
The reaction of unprotected carbohydrates with aminooxy reagents to provide oximes is a key method for the construction of glycoconjugates. Aniline and derivatives serve as organocatalysts for the formation of oximes from simple aldehydes, and we have previously reported that aniline also catalyzes the formation of oximes from the more complex alde...
Article
Glycobiology, in particular the study of carbohydrate–protein interactions and the events that follow, has become an important research focus in recent decades. To study these interactions, many assays require homogeneous glycoconjugates in suitable amounts. Their synthesis is one of the methodological challenges of glycobiology. Here, we describe...
Article
Bariatric surgery is currently the most effective treatment of obesity, which has spurred an interest in developing pharmaceutical mimetics. It is thought that the marked body weight-lowering effects of bariatric surgery involve stimulated secretion of appetite-regulating gut hormones, including glucagon-like peptide 1. We here report that intestin...
Article
Full-text available
Polyglutamine (PolyQ) diseases are progressive neurodegenerative disorders caused by both protein- and RNA-mediated toxicities. We previously showed that a peptidyl inhibitor, P3, which binds directly to expanded CAG RNA can inhibit RNA-induced nucleolar stress and suppress RNA-induced neurotoxicity. Here we report a N-acetylated and C-amidated der...
Article
Non-covalent binding of biopharmaceuticals to human serum albumin protects against enzymatic degradation and renal clearance. Herein, we investigated the effect of mono- or di-valent small-molecule albumin binders for half-life extension of peptides. For proof-of-principle, the clinically relevant glucagon-like peptide 1 (GLP-1) was functionalized...
Article
Proteins anchored to membranes through covalently linked fatty acids and/or isoprenoid groups play crucial roles in all forms of life. Sorting and trafficking of lipidated proteins has traditionally been discussed in the context of partitioning to membrane domains of different lipid composition. We recently showed that membrane shape/curvature can...
Article
Peptide-oligonucleotide conjugates (POC) were used for the self-assembly of miniature coiled-coil α-helical peptides guided by oligonucleotide duplex and triplex formation. The POC consisted of three oligonucleotides each with a 23-mer peptide attached. The oligonucleotide domains gave a parallel triplex that templated the peptides to form a small...
Article
The rational design of a well-defined protein-like tertiary structure formed by small peptide building blocks is still a formidable challenge. Using peptide-oligonucleotide conjugates (POC) as building blocks, we here present the self-assembly of miniature coiled coil α-helical peptides guided by oligonucleotide duplex and triplex formation. POC sy...
Article
The targeted spatial organization (sorting) of Gprotein-coupled receptors (GPCRs) is essential for their biological function and often takes place in highly curved membrane compartments such as filopodia, endocytic pits, trafficking vesicles or endosome tubules. However, the influence of geometrical membrane curvature on GPCR sorting remains unknow...
Article
The inside cover picture shows the wide range of glycoconjugates obtainable directly from unprotected, reducing carbohydrates. There has been a tremendous increase in the number of available methods for chemoselective synthesis of glycoconjugates from native carbohydrates in aqueous solution. These methodologies allow rapid and easy access to compl...
Article
Detection of type-specific antibodies is an important and essential part of accurate diagnosis, even in silent carriers of HSV-1 (oral) and HSV-2 (genital) infections. Serologic assays that identify HSV-1 and HSV-2 type-specific antibodies have been commercially available for more than a decade but often face problems related to cross-reactivity an...
Article
Glycobiology is the comprehensive biological investigation of carbohydrates. The study of the role and function of complex carbohydrates often requires the attachment of carbohydrates to surfaces, their tagging with fluorophores, or conversion into natural or non-natural glycoconjugates, such as glycopeptides or -lipids. Glycobiology and its 'omics...
Article
principles for optimizing the properties of peptide-based drugs are needed in order to leverage their full pharmacological potential. We present the design, synthesis, and evaluation of a library of neoglycolipidated glucagon-like peptide 1 (GLP-1) analogs, which are valuable drug candidates for treatment of type 2 diabetes and obesity. Neoglycolip...
Article
Specific target binding and stability in diverse biological media is of crucial importance for applications of synthetic oligonucleotides as diagnostic and therapeutic tools. So far, these issues have been addressed by chemical modification of oligonucleotides and by conjugation with a peptide, most often at the terminal position of the oligonucleo...
Article
Full-text available
Few-atom silver nanoclusters (AgNCs) can exhibit strong fluorescence; however, they require ligands to prevent aggregation into larger nanoparticles. Fluorescent AgNCs in biopolymer scaffolds have so far mainly been synthesized in solution, and peptides have only found limited use compared to DNA. Herein, we demonstrate how solid-phase methods can...
Article
Peptides and proteins constitute a vast pool of excellent drug candidates. Evolution has equipped these molecules with superior drug-like properties such as high specificity and potency. However, native peptides and proteins suffer from an inadequate pharmacokinetic profile, and their outstanding pharmacological potential can only be realized if th...
Article
Utilisation of functionalized liposomes as the means of targeted delivery of therapeutics may enhance specific transport of biologically active drugs to target tissues, while avoiding or reducing undesired side effects. In the present investigation, peptide-conjugated cationic liposomes were constructed with the aim of targeting integrins (i.e. vit...
Article
Full-text available
Peptide-based structures can be designed to yield artificial proteins with specific folding patterns and functions. Template-based assembly of peptide units is one design option, but the use of two orthogonal self-assembly principles, oligonucleotide triple helix and a coiled coil protein domain formation have never been realized for de novo protei...
Data
Supplementary Figures 1-40, Supplementary Table 1, Supplementary Discussion, Supplementary Methods and Supplementary References.
Article
Full-text available
Three dimers of the amphipathic α-helical peptide 18A have been synthesized with different interhelical linkers inserted between the two copies of 18A. The dimeric peptides were denoted 'beltides' where Beltide-1 refers to the 18A-dimer without a linker, Beltide-2 is the 18A-dimer with proline (Pro) as a linker and Beltide-3 is the 18A-dimer linked...
Article
Full-text available
PEGylation is the most widely used method to chemically modify protein biopharmaceuticals, but surprisingly limited public data is available on the biophysical effects of protein PEGylation. Here we report the first large-scale study, with site-specific mono-PEGylation of 15 different proteins and characterization of 61 entities in total using a co...
Article
Membrane shape or geometrical curvature emerged recently as a potent regulator of membrane recruitment during protein trafficking and sorting. Cellular membranes display distinct curvature geometries e.g. spherical (trafficking- and synaptic vesicles) or cylindrical (tubes in the ER and Golgi), however quantitative studies of protein recruitment by...
Article
Protein recruitment to biological membranes is motivated by either highly selective recognition of specific target membrane components or non-specific attraction to general physical properties of the membrane, such as charge, lipid heterogeneity, and curvature. Here we discuss the interaction between lipid-anchored proteins and lipid membranes from...
Article
Controlled self-assembly (SA) of proteins offers the possibility to tune their properties or to create new materials. Herein, we present the synthesis of a modified human insulin (HI) with two distinct metal-ion binding sites, one native, the other abiotic, enabling hierarchical SA through coordination with two different metal ions. Selective attac...
Chapter
Carbohydrate-modified nanoparticles (glyconanoparticles) have been introduced as an attractive platform for studying and intervening in carbohydrate-protein and carbohydrate-carbohydrate interactions. This chapter focuses on carbohydrate-modified gold nanoparticles (AuNPs). Covalent anchoring of carbohydrates to nanoparticles requires two key linka...
Article
Insulin, a small peptide hormone, is crucial in maintaining blood glucose homeostasis. The stability and activity of the protein is directed by an intricate system involving disulfide bonds to stabilize the active monomeric species and by their non-covalent oligomerization. All known insulin variants in vertebrates consist of two peptide chains and...
Article
Surface polysaccharides are important for bacterial interactions with multicellular organisms, and some are virulence factors in pathogens. In the legume-rhizobium symbiosis, bacterial exopolysaccharides (EPS) are essential for the development of infected root nodules. We have identified a gene in Lotus japonicus, Epr3, encoding a receptor-like kin...
Article
De novo design and chemical synthesis of proteins and of other artificial structures, which mimic them, is a central strategy for understanding protein folding and for accessing proteins with novel functions. We have previously described carbohydrates as templates for the assembly of artificial proteins, so called carboproteins. The hypothesis is t...
Article
Here we report that grafting of a short antimicrobial peptide, anoplin, to chitosan polymers is a strategy for abolishing the hemolytic propensity, and at the same time increasing the activity of the parent peptide. Anoplin-chitosan conjugates were synthesized by CuAAC reaction of multiple peptides through 2-azidoacetyl groups on chitosan.
Article
Functionalized synthetic oligonucleotides are finding growing applications in research, clinical studies, and therapy. However, it is not easy to prepare them in a biocompatible and highly efficient manner. We report a new strategy to synthesize oligonucleotides with promising nucleic acid targeting and detection properties. We focus in particular...