Computational design of bio-inspired carnosine-based HOBr antioxidants

During a respiratory burst the enzyme myeloperoxidase generates significant amounts of hypohalous acids (HOX, X?=?Cl and Br) in order to inflict oxidative damage upon invading pathogens. However, excessive production of these potent oxidants is associated with numerous inflammatory diseases. It has been suggested that the endogenous antioxidant carnosine is an effective HOCl scavenger. Recent computational and experimental studies suggested that an intramolecular Cl⁺ transfer from the imidazole ring to the terminal amine might play an important role in the antioxidant activity of carnosine. Based on high-level ab initio calculations, we propose a similar reaction mechanism for the intramolecular Br⁺ transfer in carnosine. These results suggest that carnosine may be an effective HOBr scavenger. On the basis of the proposed reaction mechanism, we proceed to design systems that share similar structural features to carnosine but with enhanced HOX scavenging capabilities for X?=?Cl and Br. We find that (i) elongating the β-alanyl-glycyl side chain by one carbon reduces the reaction barriers by up to 44%, and (ii) substituting the imidazole ring with strong electron-donating groups reduces the reaction barriers by similar amounts. We also show that the above structural and electronic effects are largely additive. In an antioxidant candidate that involves both of these effects the reaction barriers are reduced by 71%.     

An Efficient Quantum Private Comparison of Equality over Collective-Noise Channels

This article proposes a collective-noise resistant QPC protocol with the help of an almostdishonest third party (TP) who may try to perform any sort of attacks to derive participants’ private secrets except colluding with any participant. The proposed scheme has some considerable advantages over the state-of-the-art QPC protocols over collective-noise channels, where it does not require any pre-shared key between the participants (Alice and Bob). Nevertheless, the proposed scheme can resist Trojan horse attacks without consuming half of the transmitted qubits and any additional equipment (wavelength filter and PNS) support. As a consequence, the proposed QPC protocol can guarantee higher qubit efficiency as compared to the others over collective noise channels.