The scorpion toxin, charybdotoxin (ChTX), is the first identified peptide inhibitor for the large-conductance Ca2+ and voltage-dependent K+ (BK) channel, and the chemical information of the interaction between ChTX and BK channel remains unclear today. Using combined computational methods, we obtained a ChTX-BK complex structure model, which correlated well with the mutagenesis data. In this complex, ChTX mainly used its beta-sheet domains to associate the BK channel with a conserved pore-blocking Lys27. Another crucial Tyr36 residue of ChTX lied over the loop connecting selectivity filter and S6 helix of BK channel, forming a hydrogen bond with Gly291 of BK channel. Besides, the unique turret region of BK channel was found to be far away from bound ChTX, which could explain the fact that many BK channel blockers show less selectivity over Kv channels. Together, all these information is helpful to reveal the diverse interactions between scorpion toxins and potassium channels and can accelerate the molecular engineering of specific inhibitor design.

No abstract

No abstract

The paper proposes a lossless quantum image encryption scheme based on substitution tables (S-box) scrambling, mutation operation and general Arnold transform with keys. First, the key generator builds upon the foundation of SHA-256 hash with plain-image and a random sequence. Its output value is used to yield initial conditions and parameters of the proposed image encryption scheme. Second, the permutation and gray-level encryption architecture is built by discrete Arnold map and quantum chaotic map. Before the permutation of Arnold transform, the pixel value is modified by quantum chaos sequence. In order to get high scrambling and randomness, S-box and mutation operation are exploited in gray-level encryption stage. The combination of linear transformation and nonlinear transformation ensures the complexity of the proposed scheme and avoids harmful periodicity. The simulation shows the cipher-image has a fairly uniform histogram, low correlation coefficients closed to 0, high information entropy closed to 8. The proposed cryptosystem provides 2256 key space and performs fast computational efficiency (speed = 11.920875 Mbit/s). Theoretical analyses and experimental results prove that the proposed scheme has strong resistance to various existing attacks and high level of security.

No abstract

No abstract

Remote-sensing images contain lots of visual information about transportation systems, geomorphic conditions, and communal facilities. The secure storage and transmission of remote-sensing images are of great significance. This paper proposes a novel image encryption scheme-based DNA bases probability and applies it to remote-sensing images for data protection. First, the plain-image is randomly encoded in DNA rules and its result participates in DNA addition with DNA mask generated by 2-D logistic map. Second, the cryptosystem executes 2-D logistic map again with DNA bases probability against differential attacks. Third, the pixel-level rearrangement and the DNA base-level rearrangement are, respectively, implemented in order of chaos sequences for permutation and diffusion. The cipher-image has a uniform distribution, low coefficients, and ideal entropy. The cryptosystem has acceptable encryption speed (speed = 0.651308Mbit/s) and high sensitivity to the plain-image and the security key. The experimental results show that the proposed algorithm can resist various existing attack schemes against remote-sensing images. INDEX TERMS Remote-sensing images, DNA bases probability, two-dimensional logistic map, base-level rearrangement.

No abstract