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Elastin-like peptides (ELPs) exhibit a reversible phase transition, known as coacervation, triggered by temperature changes. This property makes them useful as stimuli-responsive molecular materials for various applications. Among ELPs, short peptide chain lengths have some advantages over long peptide chain lengths because short ELPs can be easily obtained by chemical synthesis, allowing the use of various amino acids, including D-type and unnatural amino acids, at any position in the sequence. Moreover, the incorporated amino acids readily affect the temperature-responsive behavior of ELPs. However, to be utilized in various applications, it is necessary to develop short ELPs and to investigate their temperature-responsive properties. To obtain further insights into the temperature-responsive behavior of the short ELPs, we investigated branched short ELP analogs composed of (FPGVG)

Elastin comprises hydrophobic repetitive sequences, such as Val-Pro-Gly-Val-Gly, which are thought to be important for the temperature-dependent reversible self-association (coacervation). Elastin and elastin-like peptides (ELPs), owing to their characteristics, are expected to be applied as base materials for the development of new molecular tools, such as drug-delivery system carrier and metal-scavenging agents. Recently, several studies have been reported on the dendritic or branching ELP analogues. Although the topological difference of the branched ELPs compared to their linear counterparts may lead to useful properties in biomaterials, the available information regarding the effect of branching on molecular architecture and thermoresponsive behavior of ELPs is scarce. To obtain further insight into the thermoresponsive behavior of branched ELPs, novel ELPs, such as nitrilotriacetic acid (NTA)-(FPGVG) n conjugates, that is, (NTA)-Fn analogues possessing 1-3 (FPGVG) n (n = 3, 5) molecule(s), were synthesized and investigated for their coacervation ability. Turbidity measurement of the synthesized peptide analogues revealed that (NTA)-Fn analogues showed strong coacervation ability with various strengths. The transition temperature of NTA-Fn analogues exponentially decreased with increasing number of residues. In the circular dichroism measurements, trimerization did not alter the secondary structure of each peptide chain of the NTA-Fn analogue. In addition, it was also revealed that the NTA-Fn analogue possesses one peptide chain that could be utilized as metal-scavenging agents. The study findings indicated that multimerization of short ELPs via NTA is a useful and powerful strategy to obtain thermoresponsive molecules.

Elastin-like peptides (ELPs) are thermoresponsive biopolymers inspired by the characteristic repetitive sequences of natural elastin. As ELPs exhibit temperature-dependent reversible self-assembly, they are expected to be biocompatible thermoresponsive materials for drug delivery carriers. One of the most widely studied ELPs in this field is the repetitive pentapeptide, (VPGXG)

Elastin comprises hydrophobic repetitive sequences, such as Val-Pro-Gly-Val-Gly, which are thought to be important for the temperature-dependent reversible self-association (coacervation). Elastin and elastin-like peptides (ELPs), owing to their characteristics, are expected to be applied as base materials for the development of new molecular tools, such as drug-delivery system carrier and metal-scavenging agents. Recently, several studies have been reported on the dendritic or branching ELP analogues. Although the topological difference of the branched ELPs compared to their linear counterparts may lead to useful properties in biomaterials, the available information regarding the effect of branching on molecular architecture and thermoresponsive behavior of ELPs is scarce. To obtain further insight into the thermoresponsive behavior of branched ELPs, novel ELPs, such as nitrilotriacetic acid (NTA)–(FPGVG)n conjugates, that is, (NTA)-Fn analogues possessing 1–3 (FPGVG)n (n = 3, 5) molecule(s), were synthesized and investigated for their coacervation ability. Turbidity measurement of the synthesized peptide analogues revealed that (NTA)-Fn analogues showed strong coacervation ability with various strengths. The transition temperature of NTA-Fn analogues exponentially decreased with increasing number of residues. In the circular dichroism measurements, trimerization did not alter the secondary structure of each peptide chain of the NTA-Fn analogue. In addition, it was also revealed that the NTA-Fn analogue possesses one peptide chain that could be utilized as metal-scavenging agents. The study findings indicated that multimerization of short ELPs via NTA is a useful and powerful strategy to obtain thermoresponsive molecules.

We reported that bisphenol AF (BPAF) works as an agonist for estrogen receptor (ER) ERα but as an antagonist for ERβ. Similar results were observed for bisphenol E analogs (BPE-X) such as BPE-F, BPE-Cl, and BPE-Br, each consisting of a series of a tri-halogenated methyl group CX3 in the central alkyl moiety. It was demonstrated that the electrostatic halogen bond based on the dispersion force of halogen atoms is a major driving force in the activities of bifunctional ERα-agonist and ERβ-antagonist. Since the chlorine atoms present in bisphenol C (BPC) exist in a π-π conjugated system due to the presence of an adjacent C = C double bond, we intended to prove that BPC is also a bifunctional ERα-agonist and ERβ-antagonist exhibiting greatly enhanced agonist/antagonist activities. BPC was evaluated for its ability to activate ERα and ERβ in the luciferase reporter gene assay using HeLa cells. With high receptor-binding ability to both ERs, BPC was found to be fully active for ERα but inactive for ERβ. BPC’s definite antagonist activity in ERβ was revealed by its inhibitory activity against 17β-estradiol. Thus, BPC is a bifunctional ERα-agonist and ERβ-antagonist. These agonist/antagonist activities were discovered to be extremely high among series of halogen-containing bisphenol compounds. This comparative structure-activity study revealed that the ascending order of ERα-agonist and ERβ-antagonist activities was BPE-F ≪ BPE-Cl ≲ BPAF < BPE-Br ≪ BPC. The highly intensified receptor interaction of BPC is attributable to the presence of an n-π-π-n conjugation system mediated through the >C = CCl2 double bond.

Elastin-like peptides (ELPs) consist of distinctive repetitive sequences, such as (VPGVG)n, exhibit temperature-dependent reversible self-assembly (coacervation), and have been considered to be useful for the development of thermoresponsive materials. Further fundamental studies evaluating coacervative properties of novel nonlinear ELPs could present design concepts for new thermoresponsive materials. In this study, we prepared novel ELPs, cyclic (FPGVG)n (cyclo[FPGVG]n, n = 1–5), and analyzed their self-assembly properties and structural characteristics. Cyclo[FPGVG]n (n = 3–5) demonstrated stronger coacervation capacity than the corresponding linear peptides. The coacervate of cyclo[FPGVG]5 was able to retain water-soluble dye molecules at 40 °C, which implied that cyclo[FPGVG]5 could be employed as a base material of DDS (drug delivery system) matrices and other biomaterials. The results of molecular dynamics simulations and circular dichroism measurements suggested that a certain chain length was requ...

Elastin-like peptides (ELP) are distinct, repetitive, hydrophobic sequences, such as (VPGVG)n, that exhibit coacervation— the property of reversible, temperature-dependent self-association and dissociation. ELPs can be found in elastin and have been developed as new scaffold biomaterials. However, the detailed relationship between their amino acid sequences and coacervation properties remain obscure because of the structural flexibility of ELPs. In this study, we synthesized a novel, dimeric ELP analog (H-C(WPGVG)3-NH2)2, henceforth abbreviated to (CW3)2, and analyzed its self-assembly properties and structural factors as indicators of coacervation. Turbidity measurements showed that (CW3)2 demonstrated coacervation at a much lower concentration than its monomeric form and another ELP. In addition, the coacervate held water-soluble dye molecules. Thus, potent and distinct coacervation was obtained with a remarkably short sequence of (CW3)2. Furthermore, fluorescence microscopy, dynamic light scattering, a...

Bisphenol A and its derivatives are recognized as endocrine disruptors based on their complex effects on estrogen receptor (ER) signaling. While the effects of bisphenol derivatives on ERα have been thoroughly evaluated, how these chemicals affect ERβ signaling is less well understood. Herein, we sought to identify novel ERβ ligands using a radioligand competitive binding assay to screen a chemical library of bisphenol derivatives. Many of the compounds identified showed intriguing dual activities as both ERα agonists and ERβ antagonists. Docking simulations of these compounds and ERβ suggested that they bound not only to the canonical binding site of ERβ but also to the coactivator binding site located on the surface of the receptor, suggesting that they act as coactivator-binding inhibitors (CBIs). Receptor-ligand binding experiments using WT and mutated ERβ support the presence of a second ligand-interaction position at the coactivator-binding site in ERβ, and direct binding experiments of ERβ and a coactivator peptide confirmed that these compounds act as CBIs. Our study is the first to propose that bisphenol derivatives act as CBIs, presenting critical insight for the future development of ER signaling-based drugs and their potential to function as endocrine disruptors.

Many types of insects have been used as foods and protein sources. In this study, we investigated the usefulness of housefly larvae (Musca domestica) based on their amino acid composition and multifunctional biological activities. First, the utility of the amino acid composition of housefly larvae was evaluated by amino acid analysis. Notably, the housefly larvae contained sufficient amounts of all essential amino acids, and the amino acid composition was similar to that of hen eggs. Second, we prepared housefly larvae water extract (HLWE) using the decoction method and explored the biological activities of the extract for potential application of the extract as a functional food. HLWE showed significant antioxidant activity (75.4% at 5.00 mg/mL), angiotensin-I-converting enzyme (ACE) inhibitory activity (half-maximal inhibitory concentration [IC50] = 0.430 mg/mL), and dipeptidyl peptidase-IV (DPP-IV) inhibitory activity ([IC50] = 3.52 mg/mL). We found that the low-molecular-weight constituents ( 6 kDa) contributed to DPP-IV inhibition. Our results suggested that housefly larvae may provide a useful source of multifunctional protein.

17β-Estradiol (E2) is a natural steroid ligand for the structurally and physiologically independent estrogen receptors (ERs) ERα and ERβ. We recently observed that CF3-containing bisphenol AF (BPAF) works as an agonist for ERα but as an antagonist for ERβ. Similar results were also observed for the CCl3-containing bisphenol designated as HPTE. Both BPAF and HPTE are comprised of a tri-halogenated methyl group in the central alkyl moiety of their bisphenol structures, which strongly suggests that halogens contribute directly to the agonist/antagonist dual biological functions. We conducted this study to investigate the structure-activity relationships by assessing together newly synthesized CF3- and CBr3-containing bisphenol E analogs (BPE-X). We first tested bisphenols for their receptor binding ability and then for their transcriptional activities. Halogen-containing bisphenols were found to be fully active for ERα, but almost completely inactive for ERβ. When we examined these bisphenols for their inhibitory activities for E2 in ERβ, we observed that they worked as distinct antagonists. The ascending order of agonist/antagonist dual biological functions was BPE-F

[Image: see text] In search for enzyme inhibitors, we often encounter “promiscuous” enzyme inhibitors exhibiting nonspecific binding property toward enzyme active site. Therefore, inhibitory candidates should be mechanistically characterized as early as possible in discovery processes. However, there remains a lack of highly reliable and readily available methodology to evaluate specificity of initial hits inhibitors. The present study developed and established a novel DMSO-perturbing assay to identify promiscuous enzyme inhibitors. The assay successfully identified nonspecific binding inhibitors with a broad scope, typically by the attenuation of inhibitory activity by the influence of DMSO-addition. This attenuation would be attributed to the nonspecific binding property of inhibitors toward both productive and nonproductive (nondenatured) states of enzymes in perturbation solution. This working hypothesis was supported by spectroscopic analyses of enzyme conformations and analyses of solvent effects on perturbation. Overall, these results provided a novel concept of the DMSO-perturbing assay.

Elastin, a core protein of the elastic fibers, exhibits the coacervation (temperature-dependent reversible association/dissociation) under physiological conditions. Because of this characteristic, elastin and elastin-derived peptides have been considered to be useful as base materials for developing various biomedical products, skin substitutes, synthetic vascular grafts, and drug delivery systems. Although elastin-derived polypeptide (Val-Pro-Gly-Val-Gly)n also has been known to demonstrate coacervation property, a sufficiently high (VPGVG)n repetition number (n>40) is required for coacervation. In the present study, a series of elastin-derived peptide (Phe-Pro-Gly-Val-Gly)5 dimers possessing high coacervation potential were newly developed. These novel dimeric peptides exhibited coacervation at significantly lower concentrations and temperatures than the commonly used elastin-derived peptide analogs; this result suggests that the coacervation ability of the peptides is enhanced by dimerization. Circular dichroism (CD) measurements indicate that the dimers undergo similar temperature-dependent and reversible conformational changes when coacervation occurs. The molecular dynamics calculation results reveal that the sheet-turn-sheet motif involving a type II β-turn-like structure commonly observed among the dimers and caused formation of globular conformation of them. These synthesized peptide dimers may be useful not only as model peptides for structural analysis of elastin and elastin-derived peptides, but also as base materials for developing various temperature-sensitive biomedical and industrial products.

An endocrine-disrupting chemical Bisphenol A (BPA) binds specifically to a nuclear receptor (NR) named ERRγ. Although the importance of receptor-binding evaluation for human NRs is often stressed, the binding characteristics of so-called next-generation (NextGen) bisphenol compounds are still poorly understood. The ultimate objective of this investigation was to evaluate BPA and its NextGen analogs for their abilities to bind to 21 human NRs, the greatest members of NRs for which tritium-labeled specific ligands were available. After establishing the detailed assay conditions for each NR, the receptor binding affinities of total 11 bisphenols were evaluated in competitive binding assays. The results clearly revealed that BPA and the NextGen bisphenols of BPAF, BPAP, BPB, BPC, BPE, and BPZ were highly potent against one or more of NRs such as CAR, ERα, ERβ, ERRγ, and GR, with IC50 values of 3.3–73 nM. These bisphenols were suggested strongly to be disruptive to these NRs. BPM and BPP also appeared to be disruptive, but less potently. BPF exhibited only weak effects and only against estrogen-related NRs. Surprisingly, most doubtful bisphenol BPS was supposed not to be disruptive. The NRs to which BPA and NextGen bisphenols did not bind were RARα, RARβ, RARγ, and VDR. PPARγ, RORα, RORβ, RORγ, RXRα, RXRβ, and RXRγ, exhibited very weak interaction with these bisphenols. The ten remaining NRs, namely, ERRγ, ERβ, ERα, CAR, GR, PXR, PR, AR, LXRβ, and LXRα, showed distinctly strong binding to some bisphenols in this order, being likely to have consequential endocrine-disruption effects.

Elastin, a core protein of the elastic fibers, exhibits the coacervation (temperature-dependent reversible association/dissociation) under physiological conditions. Because of this characteristic, elastin and elastin-derived peptides have been considered to be useful as base materials for developing various biomedical products, skin substitutes, synthetic vascular grafts, and drug delivery systems. Although elastin-derived polypeptide (Val-Pro-Gly-Val-Gly)n also has been known to demonstrate coacervation property, a sufficiently high (VPGVG)n repetition number (n40) is required for coacervation. In the present study, a series of elastin-derived peptide (Phe-Pro-Gly-Val-Gly)5 dimers possessing high coacervation potential were newly developed. These novel dimeric peptides exhibited coacervation at significantly lower concentrations and temperatures than the commonly used elastin-derived peptide analogs; this result suggests that the coacervation ability of the peptides is enhanced by dimerization. Circular dichroism (CD) measurements indicate that the dimers undergo similar temperature-dependent and reversible conformational changes when coacervation occurs. The molecular dynamics calculation results reveal that the sheet-turn-sheet motif involving a type II β-turn-like structure commonly observed among the dimers and caused formation of globular conformation of them. These synthesized peptide dimers may be useful not only as model peptides for structural analysis of elastin and elastin-derived peptides, but also as base materials for developing various temperature-sensitive biomedical and industrial products.

We examined the Lewis acid catalysis of chiral Al(salalen)X complexes and found that complex 1b (X = Br) serves as an efficient catalyst for the Friedel-Crafts reaction of indole with N-[(E)-alkenoyl]oxazolidin-2-ones. High enantioselectivity (up to 98% ee) was obtained under the optimized conditions.

We examined the Lewis acid catalysis of chiral Al(salalen)X complexes and found that complex 1b (X = Br) serves as an efficient catalyst for the Friedel-Crafts reaction of indole with N-[(E)-alkenoyl]oxazolidin-2-ones. High enantioselectivity (up to 98% ee) was obtained under the optimized conditions.