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β2-Adrenergic receptor (β2AR) plays a critical role in mediating the effects of catecholamine hormones. Due to the flexibility of the structure of its active state, study of agonist–β2AR is usually performed by molecular dynamic (MD) simulation. In this study we show the representative characteristics of agonist binding and activation on β2AR by MD simulation. The binding site and the conformational changes in the specific regions of β2AR are reasonable which confirmed the conclusion that agonist–β2AR reached its active-like state. We have studied the disruption of non-covalent intramolecular interactions, including the conserved DRY motif, the rotamer toggle switch and the ionic lock, the cytoplasmic ends of transmembranes 5 and 6, and some water-mediated hydrogen bond network regions. We conclude that agonist induced β2AR to its active conformation, or at least the active-like conformation. [ABSTRACT FROM PUBLISHER]

Celastrol is a novel inhibitor of the human protein complex Hsp90–Cdc37. It was found that the N-terminal domain of Cdc37 (Cdc37_N) was the molecular target for celastrol binding through covalent bonding. To get insight into the binding mode of celastrol in the active site of Cdc37, herein, the homology models of Cdc37_N and N-terminal/middle domain of Cdc37 (Cdc37_NM) were built. Moreover, a model of Cdc37 complexed with celastrol was obtained using docking and molecular dynamics (MD) approaches. Molecular modelling studies indicated that the middle domain of Cdc37 (Cdc37_M) might be an obbligato part of the binding pocket, which could make the pocket stable for celastrol docking. We also found that the S atom of Cys57 was closest to C6 atom of celastrol among all three cysteine residues (Cys54, Cys57 and Cys64) in the pocket, which implied that celastrol and Cys57 did have a good chance to form covalent bond. The covalent interaction between C6 atom of celastrol and Cys57 of Cdc37 could also explain the potency of celastrol to inhibit the interaction of Cdc37 and Hsp90. These findings can be used to develop novel Cdc37 inhibitors. [ABSTRACT FROM AUTHOR]

Response of C60 fullerene to a 40 fs full-width at half-maximum laser pulse with a photon energy of 2.0 eV and different laser intensities is studied by semiclassical dynamics simulation technique. The simulation results show that soon after the irradiation with a strong laser pulse, many C-C bonds abruptly break but no fragments are produced. The breaking of multiple C-C bonds induces a quick increase in the kinetic energy and potential energy and a decrease in electronic energy. These results suggest that the opening of the C60 cage is an effective channel for the conversion of electronic energy to kinetic energy for the electronically excited C60 fullerene. [ABSTRACT FROM AUTHOR]

Dynamic simulations under stress were carried out on a series of main-chain polymers containing two types of mesogen. One mesogen is orientated in-line with the chain (end-to-end) and the second (swivelling) has the main chain passing at right angles through it. Under strain the swivelling mesogens are expected to rotate, pushing apart the neighbouring chains. Polymers incorporating 50% of both mesogens showed a reduced Poisson's ratio. In particular, swivelling mesogens of seven rings length produced a negative Poisson's ratio, and thus should be auxetic. In contrast, polymers containing only end-to-end mesogens had relatively high Poisson's ratios of 0.53–0.59. [ABSTRACT FROM AUTHOR]