Energy Landscape and Global Optimization for a Frustrated Model Protein

The three-color (BLN) 69-residue model protein was designed to exhibit frustrated folding. We investigate the energy landscape of this protein using disconnectivity graphs and compare it to a Go model, which is designed to reduce the frustration by removing all non-native attractive interactions. Finding the global minimum on a frustrated energy landscape is a good test of global optimization techniques, and we present calculations evaluating the performance of basin-hopping and genetic algorithms for this system.Comparisons are made with the widely studied 46-residue BLN protein.We show that the energy landscape of the 69-residue BLN protein contains several deep funnels, each of which corresponds to a different β-barrel structure

Thermal decomposition of polystyrene-b-poly(2-vinylpyridine) coordinated to co nanoparticles

Direct pyrolysis mass spectrometry analyses of polystyrene-block-poly(2-vinylpyridne), PS-b-P2VP, indicated that the thermal degradation of each component occurred independently through the decomposition pathways proposed for the corresponding homopolymers; depolymerization for PS and depolymerization and loss of protonated oligomers for P2VP by a more complex degradation mechanism. On the other hand, upon coordination to cobalt nanoparticles, thermal decomposition of the P2VP blocks was initiated by loss of pyridine units, leaving an unsaturated and/or crosslinked polymer backbone that degraded at relatively high temperatures. © 2009 Elsevier Ltd. All rights reserved

Polymorphisms at the 5' flanking region of the HSP90AA1 gene in native Turkish sheep breeds

In this study, several polymorphisms in the gene encoding the inducible form of the cytoplasmic Hsp90 (HSP90AA1) were characterized in 10 sheep breeds reared in different climatic regions of Turkey. A new indel (AA) polymorphism located at the -704 position in the HSP90AA1 5' flanking region was found in all investigated breeds. This polymorphism create/remove a GR transcription site that could affect heat stress response and is completely linked with the C/G transversion located at -660 in the same region of the gene. Genotype frequencies differed significantly between breeds. No clearcut relationship was found between this polymorphism and climate factors, but breeds from northern Turkey had higher frequencies of the indel AA allele than breeds from southern Turkey. © 2012 Elsevier B.V