Enhanced cell growth, production, and mAb quality produced in Chinese hamster ovary-K1 cells by supplementing polyamine in the media.

Polyamines such as putrescine (PUT), spermidine (SPD), and spermine (SPM) are amine group-containing biomolecules that regulate multiple intracellular functions such as proliferation, differentiation, and stress response in mammalian cells. Although these biomolecules can be generated intracellularly, lack of polyamine-synthesizing activity has occasionally been reported in a few mammalian cell lines such as Chinese hamster ovary (CHO)-K1; thus, polyamine supplementation in serum-free media is required to support cell growth and production. In the present study, the effects of biogenic polyamines PUT, SPD, and SPM in media on cell growth, production, metabolism, and antibody quality were explored in cultures of antibody-producing CHO-K1 cells. Polyamine withdrawal from media significantly suppressed cell growth and production. On the other hand, enhanced culture performance was achieved in polyamine-containing media conditions in a dose-dependent manner regardless of polyamine type. In addition, in polyamine-deprived medium, distinguishing metabolic features, such as enriched glycolysis and suppressed amino acid consumption, were observed and accompanied by higher heterogeneity of antibody quality compared with the optimal concentration of polyamines. Furthermore, an excessive concentration of polyamines negatively affected culture performance as well as antibody quality. Hence, the results suggest that polyamine-related metabolism needs to be further investigated and polyamines in cell growth media should be optimized as a controllable parameter in CHO cell culture bioprocessing. KEY POINTS: • Polyamine supplementation enhanced cell growth and production in a dose-dependent manner • Polyamine type and concentration in the media affected mAb quality • Optimizing polyamines in the media is suggested in CHO cell bioprocessing.

Copper-Catalyzed Regiodivergent Internal Allylic Alkylations.

We report a copper-catalyzed, regioselective, and stereospecific alkylation of unbiased internal allylic carbonates with functionalized alkyl and aryl Grignard reagents. The reactions exhibit high stereospecificity and regioselectivity for either SN 2 or SN 2' products under two sets of copper-catalyzed conditions, which enables the preparation of a broad range of products with E-alkene selectivity. Density functional theory calculations reveal the origins of the regioselectivity based on the different behaviors of homo- and heterocuprates.

Harnessing Ionic Interactions and Hydrogen Bonding for Nucleophilic Fluorination.

We review recent works for nucleophilic fluorination of organic compounds in which the Coulombic interactions between ionic species and/or hydrogen bonding affect the outcome of the reaction. SN2 fluorination of aliphatic compounds promoted by ionic liquids is first discussed, focusing on the mechanistic features for reaction using alkali metal fluorides. The influence of the interplay of ionic liquid cation, anion, nucleophile and counter-cation is treated in detail. The role of ionic liquid as bifunctional (both electrophilic and nucleophilic) activator is envisaged. We also review the SNAr fluorination of diaryliodonium salts from the same perspective. Nucleophilic fluorination of guanidine-containing of diaryliodonium salts, which are capable of forming hydrogen bonds with the nucleophile, is exemplified as an excellent case where ionic interactions and hydrogen bonding significantly affect the efficiency of reaction. The origin of experimental observation for the strong dependence of fluorination yields on the positions of -Boc protection is understood in terms of the location of the nucleophile with respect to the reaction center, being either close to far from it. Recent advances in the synthesis of [18F]F-dopa are also cited in relation to SNAr fluorination of diaryliodonium salts. Discussions are made with a focus on tailor-making promoters and solvent engineering based on ionic interactions and hydrogen bonding.

Silencing of an α-dioxygenase gene, Ca-DOX, retards growth and suppresses basal disease resistance responses in Capsicum annum.

Alpha-dioxygenases (α-DOX) catalyzing the primary oxygenation of fatty acids to oxylipins were recently found in plants. Here, the biological roles of the pepper α-DOX (Ca-DOX) gene, which is strongly induced during non-host pathogen infection in chili pepper, were examined. Virus-induced gene silencing demonstrated that down-regulation of Ca-DOX enhanced susceptibility to bacterial pathogens and suppressed the hypersensitive response via the suppression of pathogenesis-related genes such as PR4, proteinase inhibitor II and lipid transfer protein (PR14). Ca-DOX-silenced pepper plants also exhibited more retarded growth with lower epidermal cell numbers and reduced cell wall thickness than control plants. To better understand regulation of Ca-DOX, transgenic Arabidopsis plants harboring the ß-glucuronidase (GUS) reporter gene driven from a putative Ca-DOX promoter were generated. GUS expression was significantly induced upon avirulent pathogen infection in transgenic Arabidopsis leaves, whereas GUS induction was relatively weak upon virulent pathogen treatment. After treatment with plant hormones, early and strong GUS expression was seen after treatment of salicylic acid, whereas ethylene and methyl jasmonate treatments produced relatively weak and late GUS signals. These results will enable us to further understand the role of α-DOX, which is important in lipid metabolism, defense responses, and growth development in plants.

Unveiling host-guest-solvent interactions in solution by identifying highly unstable host-guest configurations in thermal non-equilibrium gas phase.

We propose a novel scheme of examining the host-guest-solvent interactions in solution from their gas phase structures. By adopting the permethylated ß-cyclodextrin (perm ß-CD)-protonated L-Lysine non-covalent complex as a prototypical system, we present the infrared multiple photon dissociation (IRMPD) spectrum of the gas phase complex produced by electrospray ionization technique. In order to elucidate the structure of perm ß-CD)/LysH+ complex in the gas phase, we carry out quantum chemical calculations to assign the two strong peaks at 3,340 and 3,560 cm-1 in the IRMPD spectrum, finding that the carboxyl forms loose hydrogen bonding with the perm ß-CD, whereas the ammonium group of L-Lysine is away from the perm ß-CD unit. By simulating the structures of perm ß-CD/H+/L-Lysine complex in solution using the supramolecule/continuum model, we find that the extremely unstable gas phase structure corresponds to the most stable conformer in solution.