On Demand Attachment and Detachment of rac-2-Br-DMNPA Tailoring to Facilitate Chemical Protein Synthesis.

Herein, we developed a bifunctional reagent rac-2-Br-DMNPA 2 for the late-stage protection of peptide cysteine. Through the identification of its t-Bu ester 1 as a more competent form under ligation conditions, facile N-terminal and side-chain caging for the model peptide and protein were accomplished. Building upon this, a one-pot ligation and photolysis strategy was applied in the synthesis of the mini-protein chlorotoxin. More importantly, we extended the utility of 2 as a bifunctional linker for traceless solid-phase chemical ligation.

Fullerene-intercalated graphene nanocontainers for gas storage and sustained release.

Molecular dynamics simulations are performed to investigate the storage capacity and sustained release of nitrogen (N2) in the graphene-based nanocontainers. Sandwiched graphene-fullerene composites (SGFC) composed of two parallel graphene sheets and intercalated fullerenes are constructed. The simulation results show that the mass density of N2 at the first layer is extremely high, due to the strong adsorption ability of graphene sheets. And N2 molecules at this adsorbed layer are thermodynamically stable. Furthermore, we analyze the storage efficiency of SGFC. In general, the gravimetric and volumetric capacities decrease with the increasing number of intercalated fullerenes. On the contrary, the stability of SGFC is enhanced by more intercalated fullerenes. We therefore make a compromise and propose that 1 fullerene per 5 nm2 graphene to build a SGFC, which is much effective to storage N2. We also verify the reversibility that N2 can sustainably release from the SGFC. Our results may provide insights into the design of graphene-based nanocomposites for gas storage and sustained release with excellent structural stability and high storage capacity. Graphical abstract.

Molecular Dynamics Simulations of the Permeation of Bisphenol A and Pore Formation in a Lipid Membrane.

Bisphenol A (BPA) is particularly considered as one of the most suspicious endocrine disruptors. Exposure to BPA may bring about possible human toxicities, such as cancerous tumors, birth defects and neoteny. One of the key issues to understand its toxicities is how BPA enters cells. In this paper, we perform molecular dynamics simulations to explore the interactions between BPA and a phospholipid membrane (dipalmitoylphosphatidylcholine, DPPC bilayer). The simulation results show that BPA can easily enter the membrane from the aqueous phase. With the increasing concentrations of BPA in the membrane, BPA tends to aggregate and form into cluster. Meanwhile, several DPPC lipids are pulled out from each leaflet and adsorbed on the cluster surface, leading to pore formation. Detailed observations indicate that the lipid extraction results mainly from the dispersion interactions between BPA cluster and lipid tails, as well as weak electrostatic attractions between lipid headgroups and the two hydroxyl groups on BPA. The lipid extraction and pore formation may cause cell membrane damage and are of great importance to uncover BPA's cytotoxicity.