A series of γ‐butyrolactam fused donor–acceptor (D–A) cyclopropanes were synthesized, and their reactivities in Lewis acid catalyzed [3+2] annulations with aromatic aldehydes and aldimines were studied. A range of γ‐butyrolactam fused tetrahydrofurans and γ‐butyrolactam fused pyrrolidines containing four contiguous stereogenic centers were generated in good‐to‐excellent yields and with exclusive diastereoselectivities and high enantiospecificity under the catalysis of 1 mol‐% of Al(OTf)3.
The genus Spartinivicinus , affiliated to the class Gammaproteobacteria , is an important marine member that produces prodiginines. Currently, its taxonomic assignment to family level is not well presented. Phylogeny of 16S rRNA gene sequences indicated that Spartinivicinus forms a monophyletic clade with Zooshikella , which is neighboured by Aestuariirhabdus of the family Aestuariirhabdaceae and another monophyletic clade of the family Endozoicomonadaceae . The 16S rRNA gene of Spartinivicinus ruber S2-4-1HT had sequence similarities to those of Aestuariirhabdus litorea GTF13T, Zooshikella members and Endozoicomonas members of 93.4%, 93.2–93.4 and <92.5 %, respectively. Phylogenomic analysis based on 120 bacterial conserved single-copy genes highly supported placing Spartinivicinus as a sister member of Zooshikella , neighboured by Aestuariirhabdaceae and Endozoicomonadaceae members, indicating that Spartinivicinus and Zooshikella could be considered to belong to the same family. Thus, Zooshikellaceae fam. nov. is proposed to accommodate the two genera. Colonies of Spartinivicinus and Zooshikella are red-pigmented, which is different from Aestuariirhabdus (pale-yellow pigmented). The major respiratory quinone of S. ruber was ubiquinone (Q-9), similar to Zooshikella , but distinct from Aestuariirhabdus (Q-9 and Q-8). The predominant fatty acids and polar lipids of Spartinivicinus also showed a similar patterns to Zooshikella , but they were different from Aestuariirhabdus . Lastly, Spartinivicinus possessed a genome size of 6.68 Mbp and DNA G+C content of 40.1mol%, similar to Zooshikella , but much larger than Aestuariirhabdus . In addition, the 16S rRNA genes of Z. ganghwensis JC2044T and Z. marina JC333T possess sequence similarity of 99.79 %. Whole genome comparisons indicated that they shared 79.8 % digital DNA–DNA hybridization, 97.78 % average nucleotide identity and 97.31 % average amino acid identity values. Activities of catalase and oxidase for the two strains were positive. Hydrolysis of skimmed milk and Tweens (40, 60 and 80) was positive. Interestingly, the two strains produced different kinds of prodiginines. We propose that Z. marina is a later heterotypic synonym of Zooshikella ganghwensis .
Density functional theory (DFT) was used to investigate the reaction mechanisms of ruthenium (II)-catalyzed hydroacylation of isoprene with benzaldehyde, and o-methoxyl, m-methoxyl and p-methoxyl benzaldehyde. All intermediates and transition states were entirely optimized at the B3LYP/6-31G(d,p) level (LANL2DZ(f) for Ru). The results demonstrated that the hydroacylation had two di®erent catalytic cycles (path I and II), path II was more favorable than path I. Ru(II)-catalyzed hydroacylation began from the¯rst catalytic cycle, and the nucleophilic reaction was the rate-determining step. The activation barriers of hydrogen migration were the highest in two catalytic cycles, so the hydrogen migration was the rate-determining step. The activation barrier of hydrogen migration could be broken down to two parts: the free energy of exchange (ÁG ex ) and the relative free energy of transition state (ÁG). The ligand exchange energy (ÁG ex ) had more contribution to the activation barrier than the relative free energy of transition state (ÁG), so the ligand exchange would control these hydroacylation. Furthermore, our calculations also described the substituent e®ect, and the results indicated that four aldehydes showed di®erent chemical reactivity, and benzaldehyde and m-methoxyl benzaldehyde were predicted to have the best reactivity in ruthenium hydride-catalyzed hydroacylation.
Malate dehydrogenase (mMDH) and citrate synthase (CS) are sequential enzymes in Krebs cycle. mMDH, CS and the complex between mMDH and CS (mMDH+CS) were treated with nitric oxide solution. The roles of NO on the secondary structures and the interactions between mMDH and CS were studied using circular diehroism (CD) and Fourier transform surface plasmon resonance (FT-SPR), respectivley. The effects of NO on the activities of mMDH, CS and mMDH+CS were also studied. And the regulations by NO on mMDH and CS were simulated by PyMOL software. The results of SPR confirmed that strong interaction between mMDH and CS existed and NO could significantly regulate the interaction between the two enzymes. NO reduced the mass percents of α-helix and increased that of Random in mMDH, CS and mMDH+CS. NO increased the activities of CS and mMDH+CS, and inhibited the activity of mMDH. Graphic simulation indicated that covalent bond was formed between NO and Asn242 in active site of CS. However, there was no direct bond between NO and mMDH. The increase in activity of mMDH+CS complex depended mostly on the interaction between NO and CS. All the results suggested that the regulations by NO on the activity and interaction between mMDH and CS were accord with the changes in mMDH, CS and mMDH+CS caused by NO.
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