Short Side Chains Research Articles

Nanostructures, Linear Rheological Responses, and Tunable Mechanical Properties of Microphase-Separated Cellulose-graft-Diblock Bottlebrush Copolymer Elastomers.

A series of cellulose-graft-diblock bottlebrush copolymer elastomers (cellulose-graft-poly(n-butyl acrylate)-block-poly(methyl methacrylate) (Cell-g-PBA-b-PMMA)) with short side chains were synthesized via successive atom transfer radical polymerization (ATRP) to study the influence of varying compositions and lengths of the graft diblock side chains on microphase morphologies and properties. The microphase-separated morphologies from misaligned spheres to cylinders were observed by atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) measurements. These bottlebrush copolymer elastomers possessed thermal stability and enhanced mechanical properties because the PMMA outer block could self-assemble into hard microdomains, which served as physical cross-links. The viscoelastic responses of these bottlebrush copolymers within the linear viscoelastic (LVE) regime were carried out by the oscillatory shear rheology. The time-temperature superposition (tTs) principle was applied to construct the master curves of the dynamic moduli, and the sequential relaxation of dense bottlebrush copolymers with different PMMA hard outer block lengths was analyzed. The rheological behaviors in this work could be utilized to build up the connection of microstructures and properties for the application of these bottlebrush copolymers as high-performance thermoplastic elastomers.

Ultrafast Bioorthogonal Spin-Labeling and Distance Measurements in Mammalian Cells Using Small, Genetically Encoded Tetrazine Amino Acids.

Site-directed spin-labeling (SDSL)─in combination with double electron-electron resonance (DEER) spectroscopy─has emerged as a powerful technique for determining both the structural states and the conformational equilibria of biomacromolecules. DEER combined with in situ SDSL in live cells is challenging since current bioorthogonal labeling approaches are too slow to allow for complete labeling with low concentrations of spin label prior to loss of signal from cellular reduction. Here, we overcome this limitation by genetically encoding a novel family of small, tetrazine-bearing noncanonical amino acids (Tet-v4.0) at multiple sites in proteins expressed in Escherichia coli and in human HEK293T cells. We achieved specific and quantitative spin-labeling of Tet-v4.0-containing proteins by developing a series of strained trans-cyclooctene (sTCO)-functionalized nitroxides─including a gem-diethyl-substituted nitroxide with enhanced stability in cells─with rate constants that can exceed 106 M-1 s-1. The remarkable speed of the Tet-v4.0/sTCO reaction allowed efficient spin-labeling of proteins in live cells within minutes, requiring only sub-micromolar concentrations of sTCO-nitroxide. DEER recorded from intact cells revealed distance distributions in good agreement with those measured from proteins purified and labeled in vitro. Furthermore, DEER was able to resolve the maltose-dependent conformational change of Tet-v4.0-incorporated and spin-labeled MBP in vitro and support assignment of the conformational state of an MBP mutant within HEK293T cells. We anticipate the exceptional reaction rates of this system, combined with the relatively short and rigid side chains of the resulting spin labels, will enable structure/function studies of proteins directly in cells, without any requirements for protein purification.

Influence of strong bromine binding complexing agent in electrolytes on the performance of hydrogen/bromine redox flow batteries

1-n-Hexylpyridin-1-ium bromide [C6Py]Br is investigated in this work as bromine complexing agent (BCA) in aqueous bromine electrolytes on its influence on hydrogen bromine redox flow battery (H2/Br2-RFB) performance. [C6Py]+-cations bind bromine of aqueous polybromide solutions safely in an additional fused salt phase limiting the vapor pressure of Br2. Dissolved in aqueous electrolyte solutions, however, [BCA]+ cations drastically lower PFSA membranes' conductivity in the H2/Br2-RFB. In this work the combination of the very strong bromine-binding [C6Py]+cation and an excess of bromine in the electrolyte lead to an almost complete absorption of 99.6 mol% [C6Py]+ into the fused salt within the electrolyte's operation range. In comparison to similar application of short side chain 1-ethylpyridinium bromide, adverse effects are stronger compensated by use of [C6Py]Br. Increases in membrane resistance of the membrane in contact with [C6Py]+ cations are reversible in contrast for contact with [C2Py]+ cations. Electrolytes are cycled for at least 12 cycles and offer a stable useable capacity of 176.7 Ah L−1 and reach and stable discharge energy densities of 138.91 Wh L−1. Strong bromine binding properties between [C6Py]+ cations and polybromides are confirmed by DFT studies. In contrast to [C2Py]+ electrolytes, the long-chain [C6Py]+ cation in electrolytes has a higher cycling stability or a low decrease in capacity and energy density.

Adsorbing Volatile Organic Compounds within Bitumen Improves Colloidal Stability and Air Quality

The mass loss of bitumen due to volatilization is one of the deterioration mechanisms through which the chemical composition of bitumen deviates from its original condition, leading to change in the physical and rheological properties of bitumen. The emissions from bitumen not only accelerate its aging but also negatively impact air quality and consequently human health. Here, we characterized the molecular compositions of the volatiles emitted from bitumen in an isothermal aging process (150 °C for 24 h). We also investigated the impact of losing these compounds on the association behavior of asphaltene stacks. Based on the GC-MS results, the main mass loss of SARA (saturates, aromatics, resins, asphaltenes) fractions is attributed to the emission of lightweight nonpolar aromatic and aliphatic compounds. The most dominant volatiles are single-ring aromatics carrying short side chains, followed by saturated and unsaturated aliphatic compounds including short-chain n-alkanes, iso-alkanes, cyclic alkenes, alkenes, and dienes. Using molecular modeling in the framework of density functional theory (DFT), we showed how the reduction in aromatics and saturates can impact the colloidal stability of asphaltenes in the matrix of bitumen. Based on the DFT results, the surface adsorption of aromatics and saturates on asphaltene planes provides the steric repulsion required to maintain the asphaltene planes at a distance sufficient to inhibit their agglomeration. In addition, aromatic molecules with the least hindrance repulsion can disturb the π–π interfacial interactions between asphaltene planes, facilitating their deagglomeration. Therefore, a direct consequence of the mass loss of bitumen due to volatilization is disturbing the asphaltene distribution within the bitumen and stimulating the aggregation of asphaltenes. We also studied the merits of incorporating biochar into the bitumen surface to reduce bitumen’s mass loss. Modification of bitumen separately with each of six biochars derived from biomass feedstocks (walnut shell, peanut shell, Douglas fir, pine bark, birch, and algae) showed the efficacy of each biochar to reduce the volatiles emitted from bitumen, thereby reducing the changes in the composition of maltene with consequent colloidal stability losses. The study outcomes highlight the importance of reducing emissions from bitumen to delay its aging and minimize negative impacts on air quality and human health.

Effect of molecular structure of polycarboxylate ether superplasticizer on its tolerance to montmorillonite

Two groups of polycarboxylate ether (PCE) superplasticizers with different side chain lengths and densities were synthesized and characterized. Their dispersion capability was evaluated by the time-dependent rheological properties of cement pastes without and with montmorillonite (MMT). The adsorption and intercalation behaviors of these PCEs on MMT were investigated and their interactions with MMT were revealed. Results indicate that PCE with shorter side chains or higher side chain densities exhibits stronger tolerance to MMT than that with longer side chains or lower side chain densities, when they have comparable dispersion capability to cement particles. PCE with shorter side chains has lower adsorption on pure MMT and decreases the proportion of intercalated MMT. The adsorption of PCE on MMT decreases with the increase of side chain density, but the intercalation proportion shows an opposite behavior. The introduction of more side chains increases the intercalation efficiency, and decreases the consumption of MMT to PCE molecules. The adsorption kinetics of PCEs on cement or MMT system are well fitted by the pseudo-second-order adsorption kinetic equation, regardless of PCE type.

High-throughput experimentation for discovery of biodegradable polyesters

The consistent rise of plastic pollution has stimulated interest in the development of biodegradable plastics. However, the study of polymer biodegradation has historically been limited to a small number of polymers due to costly and slow standard methods for measuring degradation, slowing new material innovation. High-throughput polymer synthesis and a high-throughput polymer biodegradation method are developed and applied to generate a biodegradation dataset for 642 chemically distinct polyesters and polycarbonates. The biodegradation assay was based on the clear-zone technique, using automation to optically observe the degradation of suspended polymer particles under the action of a single Pseudomonas lemoignei bacterial colony. Biodegradability was found to depend strongly on aliphatic repeat unit length, with chains less than 15 carbons and short side chains improving biodegradability. Aromatic backbone groups were generally detrimental to biodegradability; however, ortho- and para-substituted benzene rings in the backbone were more likely to be degradable than metasubstituted rings. Additionally, backbone ether groups improved biodegradability. While other heteroatoms did not show a clear improvement in biodegradability, they did demonstrate increases in biodegradation rates. Machine learning (ML) models were leveraged to predict biodegradability on this large dataset with accuracies over 82% using only chemical structure descriptors.

Comparison of structures and emulsifying properties between water-extracted pectins from Fructus aurantii

The structural characteristics of two water-extracted pectic polysaccharides from Fructus aurantii were investigated, and the impacts of their structures on the emulsifying stability were evaluated. FWP-60 (extracted by cold water and followed 60 % ethanol precipitation) and FHWP-50 (extracted by hot water and followed 50 % ethanol precipitation) were both high methyl-esterified pectins, which were composed of homogalacturonan (HG) and highly branched rhamnogalacturonan I (RG-I) regions. The weight-average molecular weight, methyl-esterification degree (DM) and HG/RG-I ratio of FWP-60 were 1200 kDa, 66.39 % and 4.45, respectively, which were 781 kDa, 79.10 % and 1.95 for FHWP-50. The methylation and NMR analysis of FWP-60 and FHWP-50 demonstrated that the main backbone consisted of different molar ratios of →4)-α-GalpA-(1 → and →4)-α-GalpA-6-O-methyl-(1 →, and the side chains contained arabinan and galactan. Moreover, the emulsifying properties of FWP-60 and FHWP-50 were discussed. Compared with FHWP-50, FWP-60 had better emulsion stability. Overall, pectin had a linear HG domain and a small number of RG-I domain with short side chains to facilitate the stabilization of emulsions in Fructus aurantii. A comprehensive knowledge of the structure characteristic and emulsifying property would enable us to provide more information and theoretical guidance for the structure and emulsion preparation of Fructus aurantii pectic polysaccharides.

Solution Characterization of PEGL, a Water-Soluble, Non-Ionic, Helical Polypeptide

In this work, a non-ionic, water-soluble rigid rod polymer was investigated for viability in replacing organic-soluble rigid rod polymers as these legacy rigid polymers require difficult solvents. Producing a rigid, water-soluble polymer that does not suffer from aggregation or ionic effects is a difficult proposition. Herein, the synthesis of a poly(lysine) with a short ethylene glycol side chain, PEGL, was duplicated, based on previous work by Deming et al. and characterized by various techniques. It was discovered that PEGL suffers from aggregation, evidenced by dynamic and static light scattering experiments that showed non-ideal rigid rod behavior and multiple decay rates. PEGL also showed a changing lower critical solution temperature when varying salt concentration. Although PEGL can exhibit a double helix conformation and has non-ionic side chains, the propensity for aggregation precludes PEGL from being used for fundamental polymer investigation.

Highly ductile, stable, and efficient organic photovoltaic blends enabled by polymerized ladder-type heteroheptacene-based small-molecule acceptors

Although many fully-conjugated polymerized small-molecule acceptors (PSMAs) with high photovoltaic performance have been reported recently, most of them exhibit high stiffness and are very brittle, which limits their applications in wearable and stretchable electronics. In this work, we show that PSMAs using ladder-type heteroheptacene-cored SMAs (M-series acceptors) as the main building blocks can achieve high mechanical ductility while maintaining high power conversion efficiencies (PCEs). To finely tune molecular stacking and miscibility of the resulting PSMAs (PQ-HD and PQ-OD), two pendant groups with different alkyl lengths (namely, 2-hexyldecyl and 2-octyldodecyl) are anchored on their backbones. With the shorter side-chains, a more intermixed bulk-heterojunction blend morphology as well as highly well-ordered molecular packing are achieved, leading to simultaneous enhancement of both photovoltaic and mechanical properties. The best-performing PSC based on PQ-HD with 2-hexyldecyl side-chains shows a high PCE of 13.36% and excellent mechanical stretchability with a crack-onset strain (COS) of 17.5%, both of which are superior to that based on PQ-OD with 2-octyldodecyl side-chains (PCE = 10.87% and COS = 12.8%). Moreover, the PQ-HD-based PSC also exhibits excellent thermal stability. These outstanding properties in combination with its low synthetic complexity shall make PQ-HD a promising candidate for future applications in flexible and wearable devices.

Study on the dispersion performance and mechanism of polycarboxylate superplasticizer by the long side‐chain dicarboxyl terminated

AbstractThe steric hindrance formed by polyether side chains is the key factor determining the dispersion performance of polycarboxylate superplasticizer (PCE). While with the increase of the side chain length, the coiled conformation of side chain will prevent the dispersion ability of PCE from being further improved. In this work, the methallyl polyoxyethylene ether (HPEG) was esterified with tricarballylic acid (TA) to obtain dicarboxyl terminated macromonomer, and further used to synthesize polycarboxylate (PCETA). The fluidity tests show that compared with ordinary PCE‐B2400 with short side chain, the dispersion performance of PCETA‐2400 was slightly improved. While for the PCEs with long side chain, the dispersion ability of PCETA‐4000 was significantly improved than that of ordinary PCE‐B4000. The adsorption layer thickness of PCETA‐4000 adsorbed on the surface of SiO2 sphere measured by dynamic light scattering is 7.93 nm, which is 1.3 times that of PCE‐B4000. Due to electrostatic repulsion between the carboxylic groups, the stretching of long side‐chain forms stronger steric hindrance and enhancing the dispersion of cement particles. In addition, PCETA also shows good slump retention and clay resistance properties, and it is an excellent multi‐functional concrete admixture with great application potential.

Plasticizer phthalate esters degradation with a laccase from Trametes versicolor: effects of TEMPO used as a mediator and estrogenic activity removal.

Phthalate esters (PAEs) are toxic and persistent chemicals that are ubiquitous in the environment and have attracted worldwide attention due to their threats to the environment and human health. Dimethyl phthalate (DMP) is a relatively simple structure and one of the most observed PAEs in the environment. This study investigated the degradation of the DMP using Trametes versicolor laccase and its laccase-mediator systems. The degradation effect of laccase alone on DMP was poor, while the laccase-mediator systems can effectively enhance the degradation efficiency. Within 24h, 45% of DMP (25mg/L) was degraded in the presence of 0.8 U/mL laccase and 0.053mM 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO). A certain concentration (1mM) of metal ions Al3+, Cu2+ or Ca2+ can positively promote DMP degradation with the laccase-TEMPO system. Moreover, the structure of PAEs also had a great influence on the degradation efficiency. Higher degradation efficiencies were observed when incubating PAEs with short alkyl side chains by the laccase-TEMPO system compared to that with long alkyl side chains. Additionally, the branched-chain PAEs had a better degradation effect than the straight-chain. The estrogenic activity of the DMP solution after reaction was much smaller than that of the original solution. Finally, transformation products ortho-hydroxylated DMP and phthalic acid were identified by GC-MS and the possible degradation pathway was proposed. This study verifies the feasibility of the laccase-TEMPO system to degrade PAEs and provides a reference for exploring more potential value of laccase.

Investigation of structural and transport properties of highly oxygen-permeable ionomer in polymer electrolyte membrane fuel cells using molecular dynamics simulations

Understanding the nanostructure of ionomer membranes is important for elucidating the mechanism of their molecular transport properties and for improving the performance of proton exchange membrane fuel cells. In this study, we incorporated a ring structure into the main chain of perfluorinated sulfonic acids ionomers including short side chain (SSC) as a highly oxygen-permeable ionomer and used molecular dynamics simulations to investigate the interrelation between the structural properties of the ionomer and its transport properties. The incorporated ring structure influences the stiffness of the ionomer chain and the nanostructure of the ionomer membrane. To demonstrate the influence of the ionomer structure on the transport properties and the nanostructural features such as water channels, the structure and water volume were analyzed and the water-cluster connectivity was calculated for modified SSC ionomers and long side chain (LSC) ionomer, and the results were compared. Compared with the LSC ionomer, the modified SSC ionomer exhibits better oxygen transport properties but worse water transport properties because of its stiff chain derived from the ring structure.

Outer sidechain engineering of selenophene and thiophene-based Y-series acceptors to produce efficient indoor organic solar cells

In recent years, efficient indoor organic photovoltaics (OPVs) have emerged as promising energy harvesters to drive Internet of Nanothings (IoNT) applications. The diverse design strategies developed for non-fullerene acceptor (NFA) materials have dramatically increased the power conversion efficiency (PCE) of indoor OPVs to 31%, and progress tends to continue. In this context, the current study investigated the indoor performance of NFA-OPVs by modifying the chalcogen-containing heterocycle of the acceptor molecule to thiophene (ThTh) and selenophene (ThSe), and changing the length of the external side chain using n-hexyl (C6) and n-nonyl (C9) components. Compared with the ThSe systems, the ThTh-containing OPVs exhibited enhanced current densities (JSC) and open-circuit voltages (VOC) owing to their enhanced crystallinity and reduced degree of bimolecular recombination. Similarly, the introduction of a short side chain (i.e., C6) led to relatively reduced monomolecular recombination and a moderated planarity compared to the system modified with the long side chain (i.e., C9). Ultimately, this resulted in an enhanced JSC and improved charge transport properties. Finally, the optimized OPV exhibited a PCE of 24.6% under a 1000 lx light-emitting diode lamp.

The Effect of a Blended Polycarboxylate Superplasticizer on the Rheology of Self-Compacting Concrete Paste

High-strength-performing concretes (HSPC) have been used extensively due to new building requirements and their special properties suitable for modern cities. Superplasticizers (SPs) are essential components in the mix design of these concretes since they control their fresh properties and improve durability. In practice, superplasticizers are used to achieve a desired workability without increasing the water content by dispersing agglomerated cement particles. The aim of this research was to investigate the effectiveness of a blended polycarboxylate (PCE) superplasticizer on the rheological behavior for three different cements. It was found that two SP agents with the same molecular structure but with different weight and side-chain length provided an SP product that had a greater effect on the rheological properties of the cement paste. Yield stress values remained unaffected in the presence of blended SP with an SP fraction above 50% and with long side chains while its adsorption ability increased with the decrease in SP fraction with shorter side chains and lower molecular mass.

Effective fluorescent turn-on detection of ionizing radiations through controllable intramolecular photoinduced electron transfer

In order to explore the detection of gamma radiation via intramolecular photoinduced electron transfer (PET) and the interaction between molecular structures and fluorescence enhancement, we conducted an in-depth study of the perylene tetracarboxylic diimide (PDI) series of fluorescent probes capable of detecting HCl in the non-polar CHCl3 solutions. To simulate the interaction between ionizing radiation and fluorescent molecules, we used HCl titration method to predict the ability of PDI-n to detect gamma rays. The results show that the combination of PDI-n and HCl can enhance the fluorescence through retro-PET process. In addition, the fluorescence enhancement multiple gradually decreased with the enlargement of alkylamine side chains. In the direct irradiation experiment of ionizing radiation, PDI-n can also show a good fluoresence enhancement to gamma rays. Similar to the above HCl titration tests, the fluorescence increament stronthly depends on the alkylamine side chains lengths. The maximum fluorescence increament of PDI-1 is 22.24, and the fluorescence enhancement multiple of PDI-1–PDI-4 decreases when increasing the alkyl chain length. Besides, combining density functional theory (DFT), time-dependent density functional theory (TDDFT) calculations and electrochemical tests, the relative positions of each energy level obtained from the experiment indicate that the PDI-n molecule is beneficial to the occurrence of the intramolecular PET effect. Using femtosecond transient absorption spectroscopy (fs-TAS) and transient fluorescence spectroscopy (TFS) tests, the lifetime of charge separation was obtained, and the efficiency of the PET process was characterized by the rate constant. We found that fluorescent molecules with shorter side chains can realize PET more efficiently. Therefore, this work exploits the intramolecular PET mechanism for efficiently detecting gamma rays using a series of fluorescent probes, and reveals the law of the influence of molecular chain length on the PET effect. Which provides theoretical support for the development of new materials for effective and sensitive detection of ionizing radiation.

Detection of a novel intramolecular rearrangement during gramine biosynthesis in barley using stable isotope-labeled tryptophan

Plants accumulate various secondary metabolites, and the biosynthetic reactions responsible for their scaffold construction are the key steps that characterize their structural categories. Gramine, an indole alkaloid, is a defensive secondary metabolite biosynthesized in barley (Hordeum vulgare) from tryptophan (Trp) via aminomethylindole (AMI). While the two sequential N-methylation steps following the formation of AMI have already been characterized both genetically and enzymatically, the step preceding AMI formation, which includes the Trp side chain-shortening, has not yet been revealed. To gain further insight into these biosynthetic reactions, barley seedlings were fed Trp labeled with stable isotopes (13C and 15N) at various positions, and the isotope incorporation into gramine was analyzed by liquid chromatography/mass spectrometry. Significant increases in the abundance of isotopic gramine were detected in experimental sets in which Trp was labeled at either the indole ring, the β-carbon, or the amino group, whereas the isotopolog composition was not affected by α-carbon-labeled Trp. Although absorbed Trp presumably undergoes transamination in plants, this reaction did not seem to be related to gramine productivity. The data indicated that AMI directly inherited the amino group from Trp, while the α-carbon was removed, suggesting that the Trp–AMI conversion includes a novel intramolecular rearrangement reaction. The results of this study provide novel insights into scaffold formation in plant secondary-metabolite synthesis.

Biodiesel as Dispersant to Improve the Stability of Asphaltene in Marine Very-Low-Sulfur Fuel Oil

Since the implementation of the sulfur cap legislation in 2020, marine very-low-sulfur fuel oil, often known as VLSFO, has become a crucial source of fuel for the contemporary shipping industry. However, both the production and utilization processes of VLSFO are plagued by the poor miscibility of the cutter fraction and the residual fraction, which can result in the precipitation of asphaltene. In this study, biodiesel was chosen as a cutter fraction to improve the stability and compatibility of asphaltene in VLSFO because of its environmental benefit and strong solubility. The average chemical structure of asphaltene derived from the marine low-sulfur fuel oil sample was analyzed using element analysis, FTIR, 1HNMR, and time-flight spectroscopy. The composition of biodiesel was analyzed using GC-MS. It was found that the asphaltene had a feature of a short side chain, low H/C ratio, high aromaticity, and a high proportion of heteroatoms. Both laboratory experiments and molecular dynamic simulations were applied to investigate the dispersion effect and mechanism compared with other dispersants. The dispersion effect of biodiesel was studied using measurements of the initial precipitation point (IPP), dispersion improvement rate, and morphology of asphaltene in the model oil. Experimental results revealed that biodiesel was fully compatible with heavy fuel oil and that it can postpone the IPP from 46% to 54% and increase the dispersion improvement rate to 35%. Molecular dynamics (MDs) simulation results show that biodiesel can form strong interactions with the fused aromatics structures and heteroatoms in the asphaltene; such interactions can increase the solubility of asphaltene and acts as a “connection bridge” to promote the dispersion effect of asphaltene molecules.

Effect of NaOH content on the fluidizing effect of PCEs with different structures in NaOH-activated slag

The effect of NaOH content on the fluidizing effect of PCEs with varied architecture in AAS was investigated. The adsorption behavior of PCEs was measured by TOC, while their molecular stability was investigated via light transmittance and DLS. At high concentrations (>2 M), the fluidizing effect of PCEs with short side chains continuously decreased, while that of PCEs with long side chains first decreased and then increased. The decline in dispersing ability was attributed to the collapse of PCEs molecules rather than competitive adsorption of PCEs and OH−, while the subsequent improvement in the dispersing effect of PCEs with long side chains was attributed to the formation of soluble aggregates assembled by numerous PCE molecules, which resulted in a significant increase in adsorption layer thickness. PCEs with long side chains, an extremely high acid-to-ether ratio, and high molecular weight exhibited excellent dispersing effect over a wide range of NaOH concentrations.

ScrepYard: an online resource for disulfide-stabilised tandem repeat peptides.

Receptor avidity through multivalency is a highly sought-after property of ligands. While readily available in nature in the form of bivalent antibodies, this property remains challenging to engineer in synthetic molecules. The discovery of several bivalent venom peptides containing two homologous and independently folded domains (in a tandem repeat arrangement) has provided a unique opportunity to better understand the underpinning design of multivalency in multimeric biomolecules, as well as how naturally occurring multivalent ligands can be identified. In previous work we classified these molecules as a larger class termed secreted cysteine-rich repeat-proteins (SCREPs). Here, we present an online resource; ScrepYard, designed to assist researchers in identification of SCREP sequences of interest and to aid in characterizing this emerging class of biomolecules. Analysis of sequences within the ScrepYard reveals that two-domain tandem repeats constitute the most abundant SCREP domain architecture, while the interdomain "linker" regions connecting the functional domains are found to be abundant in amino acids with short or polar sidechains and contain an unusually high abundance of proline residues. Finally, we demonstrate the utility of ScrepYard as a virtual screening tool for discovery of putatively multivalent peptides, by using it as a resource to identify a previously uncharacterised serine protease inhibitor and confirm its predicated activity using an enzyme assay. This article is protected by copyright. All rights reserved.

Bionic artificial penile Tunica albuginea

Bionic artificial penile Tunica albuginea