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ABSTRACT Functions of α- and β-branch carotenoids in whole-plant acclimation to photo-oxidative stress were studied in Arabidopsis thaliana wild-type (wt) and carotenoid mutants, lutein deficient ( lut2, lut5), non- photochemical quenching1 ( npq1) and suppressor of zeaxanthin- less1 ( szl1) npq1 double mutant. Photo-oxidative stress was applied by exposing plants to sunflecks. The sunflecks caused reduction of chlorophyll content in all plants, but more severely in those having high α- to β-branch carotenoid composition ( α/ β-ratio) ( lut5, szl1npq1). While this did not alter carotenoid composition in wt or lut2, which accumulates only β-branch carotenoids, increased xanthophyll levels were found in the mutants with high α/ β-ratios ( lut5, szl1npq1) or without xanthophyll-cycle operation ( npq1, szl1npq1). The PsbS protein content increased in all sunfleck plants but lut2. These changes were accompanied by no change ( npq1, szl1npq1) or enhanced capacity (wt, lut5) of NPQ. Leaf mass per area increased in lut2, but decreased in wt and lut5 that showed increased NPQ. The sunflecks decelerated primary root growth in wt and npq1 having normal α/ β-ratios, but suppressed lateral root formation in lut5 and szl1npq1 having high α/ β-ratios. The results highlight the importance of proper regulation of the α- and β-branch carotenoid pathways for whole-plant acclimation, not only leaf photoprotection, under photo-oxidative stress. [ABSTRACT FROM AUTHOR]

Given its potential role in the synthesis of novel prebiotics and applications in the pharmaceutical industry, a strong interest has developed in the enzyme levansucrase (LSC, EC 2.4.1.10). LSC catalyzes both the hydrolysis of sucrose (or sucroselike substrates) and the transfructosylation of a wide range of acceptors. LSC from the Gram-negative bacterium Erwinia tasmaniensis (EtLSC) is an interesting biocatalyst due to its high-yield production of fructooligosaccharides (FOSs). In order to learn more about the process of chain elongation, we obtained the crystal structure of EtLSC in complex with levanbiose (LBS). LBS is an FOS intermediate formed during the synthesis of longer-chain FOSs and levan. Analysis of the LBS binding pocket revealed that its structure was conserved in several related species. The binding pocket discovered in this crystal structure is an ideal target for future mutagenesis studies in order to understand its biological relevance and to engineer LSCs into tailored products. [ABSTRACT FROM AUTHOR]

Combination of tacrine/huprine, connected through a different linker tether length, with tryptophan led to the generation of a novel, highly-potent family of multi-target directed ligands targeting key molecular mechanisms of Alzheimer's disease. Based on in vitro biological profile, the 6-chloro-tacrine-(CH2)6-L-tryptophan heterodimer S- K1035 was found to be the most potent inhibitor of human acetylcholinesterase (hAChE) and human butyrylcholinesterase (hBChE) within the series, with nanomolar IC50 values (6.31 and 9.07 nM, respectively). Moreover, S K1035 showed good ability to inhibit Aß42 self-aggregation and hAChE-induced Aß40 aggregation. The X-ray crystallographic analysis of TcAChE in complex with S-K1035 highlighted the utility of the hybridization approach used in the structure based drug design. S K1035 also exerted moderate inhibition against neuronal nitric oxide synthase (nNOS). In vivo studies displayed low toxicity profile compared to parent tacrine. S-K1035 also significantly ameliorated performances of scopolamine-treated animals. [ABSTRACT FROM AUTHOR]