An atomic view of a main aqueous conformation of cyclosporine A (CycA), an important 11-amino-acid macrocyclic immunosuppressant, is reported. For decades, it has been a grand challenge to determine the conformation of free CycA in an aqueous-like solution given its poor water solubility. Using a combination of X-ray and single-crystal neutron diffraction, we unambiguously resolve a unique conformer (A1) with a novel cis-amide between residues 11 and 1 and two water ligands that stabilize hydrogen bond networks. NMR spectroscopy and titration experiments indicate that the novel conformer is as abundant as the closed conformer in 90/10 (v/v) methanol/water and is the main conformer at 10/90 methanol/water. Five other conformers were also detected in 90/10 methanol/water, one in slow exchange with A1, another one in slow exchange with the closed form and three minor ones, one of which contains two cis amides Abu2−Sar3 and MeBmt1−MeVal11. These conformers help better understand the wide spectrum of membrane permeability observed for CycA analogues and, to some extent, the binding of CycA to protein targets.

It is generally accepted that pornography is widely consumed by young men and that mainstream heterosexual pornography is characterized by a dynamic of male sexual dominance and female submission. What is less agreed upon is whether such pornography is a source of ''sexist education'' (Flood 2010) for men or whether men engage with it in an empathic and ethical manner. In this study, we discuss findings from interviews with twenty-one young men about pornography and its consumption. They described it as normative for men to watch pornography and they described ''extreme'' content as ''normal.'' It was clear that they were unused to having to account for the appeal of pornography. Men's discussion of male sexual dominance and female submission, and violence against women, within pornography was characterized by detachment. Most of the men did not take up the challenge to notice and critically respond to the sexism within the material they described. There were some exceptions, with a minority of the participants reflecting on the ethical dilemmas posed by their consumption of such pornography.

Our knowledge of amyloid formation and cytotoxicity originating from self-assembly of α-helical peptides is incomplete. PSMα3 is the only system where high-resolution X-ray crystallography and toxicity data are available. Oligomers of multiple α-helical monomers are less stable than those of β-strands, partially due to the lack of a consistent hydrogen-bonding network. It is challenging to preserve such oligomers in the gas phase where mass-selected structural studies using ion-mobility spectrometry mass spectrometry (IMS-MS) could be performed. As the oligomers fall apart after exiting the drift cell of the mass spectrometer, novel features that have shorter (a loss of charged species) or longer (a loss of neutral species) arrival times than expected are present together with those from the intact species. By obtaining a complete data set of PSMα3 peptides in solution and with n-dodecyl-β-d-maltoside, a micelle-forming detergent, we are able to discern the dissociated from the intact oligomers and detergent-bound complexes and correlate the reported cytotoxicity to the peptide oligomeric structures and their interactions with membrane mimetics. The study sheds new insights into the interpretation of IMS-MS data from biomolecular self-assembly studiesan important and timely topic.

CGRP concentration is elevated in migraine conditions. The protective effect of migraine against type 2 diabetes is attributed to the ability of CGRP to remodel human amylin aggregation and to suppress the secretion of mouse insulin 2 (the orthologue of human insulin).

We investigate the effect of assembly on charge transfer, charge recombination, and the persistence of radical cations in halogen-substituted triphenylamine (TPA) dimers. A series of urea-tethered TPA derivatives 1 (X = H, Cl, Br, and I) are compared, which have one phenyl group modified at the para position with a halogen. Ureas direct the assembly of these derivatives while halogen substituents influence the packing of the TPA units. These modifications affect the generation and persistence of TPA radical cations as monitored by electron paramagnetic resonance (EPR) spectroscopy. The formation and degradation pathways of the radical cations in solution and gas phase were probed by ion-mobility spectrometry mass spectrometry. In contrast, supramolecular assembly enhanced the stability of these materials as well as the persistence of their photogenerated radical cations, which appear to undergo charge recombination without degradation. Greater quantities of these radical cations are observed for the bromo and non-halogenated derivatives (1Br, 1H). Time-dependent density functional theory (TD-DFT) calculations on single molecules and hydrogen-bonded dimers suggest the stability of TPA radical cations largely depends on initial photoinduced charge separation and electronic coupling between assembled TPA dimers. The latter was found to be about 7 times stronger in 1I than in 1Br dimers, which may explain faster charge recombination and shorter lifetimes of 1I radicals. Transient absorption (TA) spectroscopy and TD-DFT were able to identify the charged species for 1Br along with the kinetic traces and measured lifetime of ∼80 ns. Fluorescence quenching studies are consistent with initial charge separation and subsequent charge transfer event between nearby TPAs. Future exploration will focus on the mobility and application of these TPA assemblies as hole transport materials.