Nicholas Reactions in the Synthesis of Dicobalt Dibenzocyclooctyne Complexes

Hexacarbonyldicobalt complexes of biaryl-substituted 4-methoxybutynones and 4-methoxy-2-butynes undergo intramolecular Nicholas reactions to form dibenzocyclooctyne–Co₂(CO)₆ complexes in good yields. Reductive decomplexation of the cyclization products is possible, and the method has been applied to a formal synthesis of isoschizandrin

Complex Reaction Dynamics in the Cerium–Bromate–2-Methyl-1,4-hydroquinone Photoreaction

Spontaneous oscillations with a long induction time were observed in the bromate–2-methyl-1,4-hydroquinone photoreaction in a batch reactor, where removal of illumination effectively quenched any reactivity. A substantial lengthening of the oscillatory window and a dramatic increase in the complexity of the reaction behavior arose upon the addition of cerium ions, in which separate bifurcation regions and mixed mode oscillations were present. The complexity has a strong dependence on the intensity of illumination supplied to the system and on the initial concentrations of the reactants. ¹H NMR spectroscopy measurements show that the photoreduction of 2-methyl-1,4-benzoquinone leads to the formation of 2-methyl-1,4-hydroquinone and the compound 2-hydroxy-3-methyl-1,4-benzoquinone. Spectroscopic investigation also indicates that the presence of methyl group hinders the bromination of the studied organic substrate 2-methyl-1,4-hydroquinone, resulting in the formation of 2-methyl-1,4-benzoquinone

Enriched GO terms for proteins with higher than expected γ not identified when analyzing positively selected protein sequences.

<p>Enriched GO terms for proteins with higher than expected γ not identified when analyzing positively selected protein sequences.</p

Evolution of protein-protein interaction networks in yeast

<div><p>Interest in the evolution of protein-protein and genetic interaction networks has been rising in recent years, but the lack of large-scale high quality comparative datasets has acted as a barrier. Here, we carried out a comparative analysis of computationally predicted protein-protein interaction (PPI) networks from five closely related yeast species. We used the Protein-protein Interaction Prediction Engine (PIPE), which uses a database of known interactions to make sequence-based PPI predictions, to generate high quality predicted interactomes. Simulated proteomes and corresponding PPI networks were used to provide null expectations for the extent and nature of PPI network evolution. We found strong evidence for conservation of PPIs, with lower than expected levels of change in PPIs for about a quarter of the proteome. Furthermore, we found that changes in predicted PPI networks are poorly predicted by sequence divergence. Our analyses identified a number of functional classes experiencing fewer PPI changes than expected, suggestive of purifying selection on PPIs. Our results demonstrate the added benefit of considering predicted PPI networks when studying the evolution of closely related organisms.</p></div

Proteins which experience a lower or higher number of changes in PPIs in the real data compared to the simulated interactomes.

<p>Proteins which experience a lower (A) or higher (B) number of changes in inferred PPIs in the real data in comparison to the simulated interactomes. Each protein’s real γ is plotted in red and the range of γ observed in the null model are plotted in black.</p

Significant protein clusters and GO term enrichment analysis results found in each of the four non-<i>cerevisaie</i> species.

<p>Significant protein clusters and GO term enrichment analysis results found in each of the four non-<i>cerevisaie</i> species.</p

Enriched GO terms in <i>S</i>. <i>kudriavzevii</i> cluster 113.

<p>Enriched GO terms in <i>S</i>. <i>kudriavzevii</i> cluster 113.</p

Enriched GO terms for proteins with lower than expected γ not identified when analyzing slowly evolving protein sequences.

<p>Enriched GO terms for proteins with lower than expected γ not identified when analyzing slowly evolving protein sequences.</p

Summary of the enriched GO Terms of the proteins participating in conserved PPIs.

<p>Summary of the enriched GO Terms of the proteins participating in conserved PPIs.</p

Distribution of the change in protein-protein interaction across the phylogeny.

<p>The distribution of γ, which represents the total number of interaction changes (gains or losses) over the entire phylogeny. The majority of proteins experience relatively few changes in interaction across the phylogeny with a small number of proteins experiencing many changes.</p