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Allatostatins are a family of related neuropeptides that play an important role in development, reproduction, and digestion in insects. The cockroach Diploptera punctata has 13 allatostatin neuropeptides, with pleiotropic functions, two of which are: inhibition of juvenile hormone (JH) production and inhibition of gut muscle contraction. In this study, the conformation and dynamics of D. punctata allatostatin 5 (Dippu-AST 5) and allatostatin 8 (Dippu-AST 8) are investigated by CD, NMR, and molecular dynamics simulations. These peptides contain eight and nine residues, respectively, and the identical six-residue C-terminal motif. Yet Dippu-AST 5 and Dippu-AST 8 affect juvenile hormone production and hindgut contraction with different potencies. Dippu-AST 5 is one of the most potent inhibitors of juvenile hormone production and one of the least potent inhibitors of gut contraction, whereas Dippu-AST 8 has the opposite potencies with respect to these tissues. From the NMR structure, it is clear that Dippu-AST 5 has a 3(10) helix involving three of its residues and a "gamma" turn at the end of its C-terminal motif. In contrast Dippu-AST 8 has an open "pi" turn among five of its central residues. In addition, the orientation preferences within the membrane of the two peptides were simulated. Our simulation results show that the C-terminal segment of Dippu-AST 5 orients in the membrane surface with an average angle of 17.5 degrees, whereas Dippu-AST 8 orients with an average angle of 5.1 degrees. Taken together, from the structures and orientation preferences of these peptides within the membrane, it appears that these peptides may interact with the receptor very differently.

Graphene, a single sp2 bonded carbon, is now a burgeoning interest with various fascinating properties in a large number of biomedical applications. Consequently, the impact of graphene-based functional nanohybrid and its potential risk to human health have raised considerable public concerns. In this present study, we have synthesized cerium oxide ( CeO 2) anchored reduced graphene oxide (RGO) nanohybrid and a detailed study on its nanotoxicity profile has also been scrutinized. To confirm the efficient synthesis of nano- CeO 2/RGO nanohybrid, the systematic characterization has been carried out using FTIR, Raman and UV-Vis spectroscopic analysis. The successful imprint of CeO 2 nanoparticles (NPs) on RGO nanosheet was also evident from the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs. A dose-dependent in vitro nanotoxicity of the nanohybrid has been assessed by using monocyte macrophage cells-Raw264.7 and colon cancer cells-HCT116 as compared with RGO and CeO 2. The results conferred that as compared with single nanostructures (RGO or CeO 2), nanohybrid showed excellent biocompatibility and no such prominence morphological alteration of the cell structure. Moreover, after exposure of different nanomaterials to HCT116 cells, the possible cellular interaction was investigated through reactive oxygen species (ROS) measurements using flow cytometry analysis dicholoro-dihydro-fluorescen dia-acetate (DCF) assay. These results conveyed that nanohybrid adapts an oxidative stress mechanism upon cellular interaction where it utilizes the scavenging property of CeO 2, which induces the cell proliferation. Overall, the nano- CeO 2/RGO nanohybrid exhibits a prolonged biocompatibility and cell viability, which is highly desired for biomedical applications.

N-glycosylation of proteins is an essential, highly conserved modification reaction that occurs in all eukaryotes and some prokaryotes. This process is catalyzed by oligosaccharyltransferase (OT), a multisubunit enzyme localized in the endoplasmic reticulum. Complete loss of N-glycosylation is lethal in all organisms. In Saccharomyces cerevisiae , OT is composed of nine nonidentical membrane proteins. Here, we report the atomic structure of an OT subunit from S. cerevisiae , Ost4p. This unusually small membrane protein containing only 36 residues folds into a well formed, kinked helix in the model-membrane solvent system used in this study. The residues critical for the OT activity and the stability of Stt3p-Ost4p-Ost3p subcomplex are located in helix α2, the larger cytosolic half of this kinked helix. The residues known to disrupt Ost4p-Stt3p complex form a well defined ridge in the 3D structure. Taking together prior mutational studies and the NMR structure of Ost4p, we propose that in the OT complex Stt3p is packed against the α2-helix of Ost4p by using a “ridges-into-grooves” model, with Met-18, Leu-21, and Ile-24 as the packing interface on one face, whereas Ost3p is involved in interactions with Met-19, Thr-20, Ile-22, and Val-23 on the other face.

Correction for ‘Toughened bio-based epoxy blend network modified with transesterified epoxidized soybean oil: synthesis and characterization’ by Sushanta K. Sahoo et al., RSC Adv., 2015, 5, 13674–13691.

In the present study, a candid approach using mechanical oxidation, for modification of multi-walled carbon nanotubes (CNTs) has been utilized, and its advantages over conventional acid oxidation methods have been established. Higher concentration of acidic groups was found in case of mechanically oxidized CNTs (i.e., McCNT) as compared to acid oxidized CNT (i.e., ACNT). Raman spectrum exhibited greater degree of transformation of sp2 carbon into sp3 carbon. X-ray diffraction (XRD) analysis revealed maintained crystalline organization in McCNT. The major finding of the study was that, the mechanical oxidation method can be used easily to replace the conventional acid treatment method. This is because in the mechanical oxidation crystalline organization of CNTs can be maintained, relatively higher number of acid groups can be incorporated, no loss to the mass of CNTs is allowed etc.

The effect of surface treated sisal fiber on the mechanical, thermal, flammability, and morphological properties of sisal fiber (SF) reinforced recycled polypropylene (RPP) composites was investigated. The surface of sisal fiber was modified with different chemical reagent such as silane, glycidyl methacrylate (GMA), and O-hydroxybenzene diazonium chloride (OBDC) to improve the compatibility with the matrix polymer. The experimental results revealed an improvement in the tensile strength to 11%, 20%, and 31.36% and impact strength to 78.72%, 77%, and 81% for silane, GMA, and OBDC treated sisal fiber reinforced recycled Polypropylene (RPP/SF) composites, respectively, as compared to RPP. The thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), and heat deflection temperature (HDT) results revealed improved thermal stability as compared with RPP. The flammability behaviour of silane, GMA, and OBDC treated SF/RPP composites was studied by the horizontal burning rate by UL-94. The morphological analysis through scanning electron micrograph (SEM) supports improves surface interaction between fiber surface and polymer matrix.

Two-dimensional 1H NMR spectroscopy has been used to investigate the binding site, binding interactions, and the conformation of a 1:1 complex of aponeocarzinostatin (apo-NCS) with ethidium bromide in solution. The protein component in the complex has been sequence-specifically assigned using information derived from coherence transfer and two-dimensional homonuclear 1H NOESY experiments. The conformation of the protein in the complex has been found to be similar to the free form of the apoprotein, and intermolecular NOEs between the residues of the protein to protons on the ethidium bromide suggest that the ethidium bromide is bound to the protein in the same cleft in which the neocarzinostatin chromophore binds. Protons on ethidium show NOE interactions to the following protein residues: Trp-39, Leu-45, Cys-47, and Gln-94 which interact with the phenanthridine ring system of ethidium, Gly-102 and Asn-103 which interact with the alkyl chain of ethidium, and Phe-52 which interacts with the phenyl ring of ethidium. The orientation of ethidium in the cleft of apo-NCS is compared and contrasted to orientation of the chromophore as determined by high-resolution NMR and X-ray diffraction studies.