Chemical characterization of the smallest S-nitrosothiol, HSNO; cellular cross-talk of H2S and S-nitrosothiols

Dihydrogen sulfide recently emerged as a biological signaling molecule with important physiological roles and significant pharmacological potential. Chemically plausible explanations for its mechanisms of action have remained elusive, however. Here, we report that H(2)S reacts with S-nitrosothiols to form thionitrous acid (HSNO), the smallest S-nitrosothiol. These results demonstrate that, at the cellular level, HSNO can be metabolized to afford NO(+), NO, and NO(-) species, all of which have distinct physiological consequences of their own. We further show that HSNO can freely diffuse through membranes, facilitating transnitrosation of proteins such as hemoglobin. The data presented in this study explain some of the physiological effects ascribed to H(2)S, but, more broadly, introduce a new signaling molecule, HSNO, and suggest that it may play a key role in cellular redox regulation.     

Randomization improves sparse sampling in multidimensional NMR

While a number of strategies have been developed to reduce data collection requirements for multidimensional NMR based on non-Fourier methods of spectrum analysis, there is an increasing awareness that the principal differences in the performance of these methods is attributable to the sampling strategies employed, and not the method of spectrum analysis per se. The ability of maximum entropy reconstruction to utilize essentially arbitrary sampling schemes makes it a useful platform for comparative analysis of sampling strategies. Here we use maximum entropy reconstruction to demonstrate that artifacts characteristic of sparse sampling result from regularity in the sampling pattern, and that they can be substantially reduced by introducing a degree of randomness to an otherwise regular sampling scheme, without requiring additional sampling.     

DSC analysis of compatibility of poly(phenyl methacrylate) and some poly(xylenyl methacrylates)

Glass transition temperatures of blends of (1) poly-(phenyl methacrylate) and poly(2,3-xylenyl methacrylate), (2) poly-(phenyl methacrylate) and poly(2,6-xylenyl methacrylates and (3) poly-(2,3-xylenyl-) and poly(2,6-xylenyl methacrylate) were measured. The data obtained suggest the existance of compatibility for blends of poly(xylenyl methacrylates) mentioned and incompatibility for both poly(phenyl methacrylate)/poly(xylenyl methacrylate) systems.