1.Mucosal acidification increases hydrogen sulfide release through up-regulating gene and protein expressions of cystathionine gamma-lyase in the rat gastric mucosa.
Mard SA1, Veisi A2, Ahangarpour A2, Gharib-Naseri MK2. Iran J Basic Med Sci. 2016 Feb;19(2):172-7.
OBJECTIVES: This study was performed to investigate the effects of mucosal acidification on mRNA expression and protein synthesis of cystathionine gamma lyase (CSE), cystathionine beta synthase (CBS), and mucosal release of H2S in gastric mucosa in rats.
2.Application of AlkBGT and AlkL from Pseudomonas putida GPo1 for selective alkyl ester ω-oxyfunctionalization in Escherichia coli.
van Nuland YM1, Eggink G2, Weusthuis RA3. Appl Environ Microbiol. 2016 Apr 15. pii: AEM.00822-16. [Epub ahead of print]
The enzyme system AlkBGT fromPseudomonas putidaGPo1 can efficiently ω-functionalize fatty acid methyl esters. Outer membrane protein AlkL boosts this ω-functionalization. In this study it is shown that whole-cells ofE. coliexpressing the AlkBGT system can also ω-oxidize ethyl nonanoate (NAEE). Co-expression of AlkBGT and AlkL resulted in 1.7-fold higher ω-oxidation activity on NAEE. With this strain, initial activity on NAEE was 70 U/gcdw, 67% of the initial activity on methyl nonanoate. In time-lapse conversions with 5 mM NAEE the main product was 9-hydroxy NAEE (3.6 mM), but also 9-oxo NAEE (0.1 mM) and 9-carboxy NAEE (0.6 mM) were formed. AlkBGT also ω-oxidized ethyl, propyl and butyl esters of fatty acids ranging from C6 to C10. Increasing the length of the alkyl chain improved the ω-oxidation activity of AlkBGT on esters of C6 and C7 fatty acids. From these esters, application of butyl hexanoate resulted in the highest ω-oxidation activity of 82 U/gcdw Co-expression of AlkL only had a positive effect on ω-functionalization of substrates with a total length of C11 or longer.
3.Highly Stereocontrolled Ring-Opening Polymerization of Racemic Alkyl β-Malolactonates Mediated by Yttrium [Amino-alkoxy-bis(phenolate)] Complexes.
Jaffredo CG1, Chapurina Y1, Kirillov E1, Carpentier JF2, Guillaume SM3. Chemistry. 2016 Apr 15. doi: 10.1002/chem.201600223. [Epub ahead of print]
Yttrium [amino-alkoxy-bis(phenolate)]amido complexes have been used for the ring-opening polymerization (ROP) of racemic alkyl β-malolactonates (4-alkoxycarbonyl-2-oxetanones, rac-MLAR s) bearing an allyl (All), benzyl (Bz) or methyl (Me) lateral ester function. The nature of the ortho-substituent on the phenolate rings in the metal ancillary dictated the stereocontrol of the ROP, and consequently the syndiotactic enrichment of the resulting polyesters. ROP promoted by catalysts with halogen (Cl, Br)-disubstituted ligands allowed the first reported synthesis of highly syndiotactic PMLAR s (Pr ≥ 0.95); conversely, catalysts bearing bulky alkyl and aryl ortho-substituted ligands proved largely ineffective. All polymers have been characterized by 1 H and 13 C{1 H} NMR spectroscopy, MALDI-ToF mass spectrometry and DSC analyses. Statistical and thermal analyses enabled the rationalization of the chain-end control mechanism. Whereas the stereocontrol of the polymerization obeyed a Markov first-order (Mk1) model for the ROP of rac-MLABz and rac-MLAAll , the ROP of rac-MLAMe led to a chain end-control of Markov second-order type (Mk2).
4.Density functional study of the electronic structure of dye-functionalized fullerenes and their model donor-acceptor complexes containing P3HT.
Baruah T1, Garnica A1, Paggen M1, Basurto L1, Zope RR1. J Chem Phys. 2016 Apr 14;144(14):144304. doi: 10.1063/1.4944469.
We study the electronic structure of C60 fullerenes functionalized with a thiophene-diketo-pyrrolopyrrole-thiophene based chromophore using density functional theory combined with large polarized basis sets. As the attached chromophore has electron donor character, the functionalization of the fullerene leads to a donor-acceptor (DA) system. We examine in detail the effect of the linker and the addition site on the electronic structure of the functionalized fullerenes. We further study the electronic structure of these DA complexes with a focus on the charge transfer excitations. Finally, we examine the interface of the functionalized fullerenes with the widely used poly(3-hexylthiophene-2,5-diyl) (P3HT) donor. Our results show that all functionalized fullerenes with an exception of the C60-pyrrolidine [6,6], where the pyrrolidine is attached at a [6,6] site, have larger electron affinities relative to the pristine C60 fullerene. We also estimate the quasi-particle gap, lowest charge transfer excitation energy, and the exciton binding energies of the functionalized fullerene-P3MT model systems.
