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Numerous studies show that the peptide aptamers are used separately to fabricate various nanostructures, as their properties of functioning as binding molecules as well as mediators for mineralization are still not understood and researched extensively. Hence, a new method for nonfabrication is developed, in which binding and mineralization by a peptide polymer is alternatively used to assemble the multilayered nanostructures.

A substantial part of the human body is made of soft tissue which is a hydrogel consisting mainly of collagen and proteoglycan fiber networks. In the last decades, great effort has been made to create artificial tissues using synthetic and biological hydrogels. Examples are superior hydrogels which exhibit excellent mechanical properties like connective tissue and extremely low frictional coefficients like synovial cartilage. A tunable photonic crystal showing a variety of structural colors using nano‐dotted hydrogel is another unique example. Various types of gel actuators with muscle‐like motility have also been developed. In this article recent trends and achievements of intelligent gels with tissue‐like functions are described after a brief overview of the extracellular matrix. © 2021 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

The use of peptide phage display methodology to isolate a peptide aptamer that electrostatically interacts with the amphoteric surface of titanium is described. Peptide motifs that bind to the surface of titanium are isolated with the long-term goal of developing artificial proteins that improve biocompatibility.

Protein contaminants in carmine can cause dyspnea and anaphylactic reactions in users and consumers of products containing this pigment. The method generally used for detection of proteins in carmine has low reproducibility and is time-consuming. In this study, a rapid, simple, and highly reproducible method was developed for the detection of protein contaminants in carmine. This method incorporates acidic protein denaturation conditions and ultrafiltration. To prevent protein aggregation, sodium dodecyl sulfate containing gel electrophoresis running buffer was used for dispersing the carmine before filtration. An ultrafiltration device was used to separate the protein contaminants from carminic acid in the carmine solution. Two ultrafiltration devices were compared, and a cylindrical device containing a modified polyethersulfone membrane gave the best results. The method had high reproducibility. [ABSTRACT FROM AUTHOR]

Novel electro-conductive and mechanically-tough double network polymer hydrogels (E-DN gels) were synthesized by polymerization of 3, 4-ethylenedioxythiophene in the presence of a double network hydrogel (DN gel) matrix. The E-DN gels showed not only excellent mechanical performance, having a fracture stress of 1.4-2.1 MPa, but also electrical conductivity as high as 10−3 S cm−1, both under dry and water-swollen states. The fracture stress and fracture energy of the E-DN gel was increased by 1.7 and 3.4 times, respectively, as compared with the DN gel. From scanning electron microscope and AFM observations, it was found that electro-conductive poly(3,4-ethylenedioxythiophene) (PEDOT) was incorporated into DN gel matrix, apparently due to the formation of a poly-ion complex with sulfonic acid group of the DN gel network. Thus, PEDOT incorporated into the DN gel matrix greatly improves not only electronic conductivity, but also mechanical properties, reinforcing the double network gel matrix. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 [ABSTRACT FROM AUTHOR]

A chemically cross-linked filamentous actin (F-actin) gel consisting of globular actin (G-actin) as repeating units was prepared. The F-actin gel was cross-linked by covalent bonds, and the main chain is represented by the self-assembly of G-actin with a high-ordered hierarchical structure. The gel exhibited good mechanical performance with a storage modulus >1 kPa and undergoes reversible sol–gel transitions in response to changes in the salt concentration (chemical-induced sol–gel transition) as well as to shear strain (mechanical-induced sol–gel transition). Therefore, the gel exhibits self-repairing ability through dynamic polymerization and depolymerization across the structure hierarchies under repeated shear stress. [ABSTRACT FROM AUTHOR]

Two isoforms of lobster muscle tropomyosin, a fast muscle type, fTm, and a slow muscle type, sTm1, are identical except for 15 residues within the region of amino acids 39–80, which corresponds to exon 2 of the tropomyosin genes of many phyla. Although the difference in the sequence does not include the terminal regions, the two isoforms are extremely different in viscosity, which is a good measure of the head-to-tail interaction strength and should be dependent on the conformation of the terminal 7–9 residues. To determine the influence of amino-acid replacements in the internal region on the overall conformation and the functional properties of the molecule, we compared the physical properties of the two isoforms and their interactions with other proteins, such as actin and myosin subfragment 1 (S1). Limited proteolysis by trypsin and chymotrypsin showed that sTm1 is more susceptible than fTm at the sites outside the region with the replaced residues. Compared with fTm, sTm1 showed higher viscosity, had a higher actin affinity, and inhibited acto-S1 ATPase to a greater extent. Finally, the binding isotherm of S1-ADP to actin-sTm1 is less sigmoidal than that to actin-fTm. These results indicate that the amino-acid replacements in the internal region alter the conformation and the physical properties of the entire molecule as well as its interactions with actin and myosin. [ABSTRACT FROM AUTHOR]

Fluorescence resonance energy transfer (FRET) spectroscopy has been used to determine spatial relationships between residues on tropomyosin and actin in reconstituted muscle thin filament, and to detect a positional change of tropomyosin relative to actin on the thin filament in the presence and absence of Ca2+ ions. In addition to Cys-190 which is a single cysteine residue in rabbit skeletal muscle α-tropomyosin, a new site, Cys-87 which is a unique cysteine residue in a mutant α-tropomyosin, was labeled with a resonance energy donor molecule, 5-(2-iodoacetylaminoethyl)aminonaphthalene 1-sulfonic acid (IAED-ANS). On the other hand, Gln-41, Lys-61, Cys-374, and the ATP-binding site of actin were selectively labeled with acceptor probes: fluorescein cadaverine, fluorescein 5-isothiocyanate, 4-dimethyl-aminophenylazophenyl 4'-maleimide, and TNP-ATP (or TNP-ADP), respectively. The distances between probes attached to position 87 of the mutant tropomyosin and Gln-41, Lys-61, Cys-374, or the nucleotide-binding site of actin on the reconstituted thin filament in the presence of Ca2+ ion were measured to be 43.2, 49.7, 45.4, and 35.2 A, respectively, and the distance between probes attached to position 190 of tropomyosin and Gln-41 or the nucleotide-binding site of actin were 51.6 and 43.1 Å, respectively. The transfer efficiencies between these donor and acceptor molecules were large, so that the efficiency should be very sensitive to changes in distance between probes attached to tropomyosin and actin. However, the transfer efficiency did not change appreciably upon removal of Ca2+ ions, suggesting that tropomyosin does not change its position on the reconstituted thin filament in response to a change in Ca2+ ion concentration. The present results do not support the notion of tropomyosin movement on skeletal muscle thin filaments as proposed in the steric blocking theory. [ABSTRACT FROM AUTHOR]

The B.1.1.7 variant of the SARS-CoV-2 virus shows enhanced infectiousness over the wild type virus, leading to increasing patient numbers in affected areas. Amino acid exchanges within the SARS-CoV-2 spike protein variant of B.1.1.7 affect inter-monomeric contact sites within the trimer (A570D and D614G) as well as the ACE2-receptor interface region (N501Y), which comprises the receptor-binding domain (RBD) of the spike protein. However, the molecular consequences of mutations within B.1.1.7 on spike protein dynamics and stability or ACE2 binding are largely unknown. Here, molecular dynamics simulations comparing SARS-CoV-2 wild type with the B.1.1.7 variant revealed inter-trimeric contact rearrangements, altering the structural flexibility within the spike protein trimer. Furthermore, we found increased flexibility in direct spatial proximity of the fusion peptide due to salt bridge rearrangements induced by the D614G mutation in B.1.1.7. This study also implies a reduced binding affinity for B.1.1.7 with ACE2, as the N501Y mutation restructures the RBD–ACE2 interface, significantly decreasing the linear interaction energy between the RBD and ACE2. Our results demonstrate how mutations found within B.1.1.7 enlarge the flexibility around the fusion peptide and change the RBD–ACE2 interface. We anticipate our findings to be starting points for in depth biochemical and cell biological analyses of B.1.1.7. [ABSTRACT FROM AUTHOR]

Xeroderma pigmentosum complementation group D (XPD) is a UV-sensitive syndrome and a rare incurable genetic disease which is caused by the genetic mutation of the excision repair cross-complementation group 2 gene (ERCC2). Patients who harbor only XPD R683W mutant protein develop severe photosensitivity and progressive neurological symptoms. Cultured cells derived from patients with XPD (XPD R683W cells) demonstrate a reduced nucleotide excision repair (NER) ability. We hope to ameliorate clinical symptoms if we can identify candidate agents that would aid recovery of the cells' NER ability. To investigate such candidates, we created in silico methods of drug repurposing (in silico DR), a strategy that utilizes the recovery of ATP-binding in the XPD R683W protein after the induced fit. We chose 4E1RCat and aprepitant as the candidates for our in silico DR, and evaluated them by using the UV-induced unscheduled DNA synthesis (UDS) assay to verify the recovery of NER in XPD R683W cells. UDS values of the cells improved about 1.4–1.7 times after 4E1RCat treatment compared with solvent-only controls; aprepitant showed no positive effect. In this study, therefore, we succeeded in finding the candidate agent 4E1RCat for XPD R683W. We also demonstrated that our in silico DR method is a cost-effective approach for drug candidate discovery. [ABSTRACT FROM AUTHOR]

The adsorption properties of a recombinant apoferritin protein fused to a gold-binding peptide were characterized. The results of quartz crystal microbalance measurements showed that the fusion protein preferentially adsorbs to gold surfaces. Scanning electron microscopy also revealed that the protein selectively adsorbed onto a nanometer-scale gold pattern on a SiO2 surface fabricated by electron-beam lithography. Our results indicate that nanodots and nanowires synthesized using a biotemplate can be selectively placed onto a gold surface by genetically modifying the outer surface of the biotemplate. This technique represents an important step toward biotemplate-mediated fabrication of a nanometer-scaled device that utilizes gold electrodes. [ABSTRACT FROM AUTHOR]