Probing the hydrophobic effect of noncovalent complexes by mass spectrometry

The study of noncovalent interactions by mass spectrometry has become an active field of research in recent years. The role of the different noncovalent intermolecular forces is not yet fully understood since they tend to be modulated upon transfer into the gas phase. The hydrophobic effect, which plays a major role in protein folding, adhesion of lipid bilayers, etc., is absent in the gas phase. Here, noncovalent complexes with different types of interaction forces were investigated by mass spectrometry and compared with the complex present in solution. Creatine kinase (CK), glutathione S-transferase (GST), ribonuclease S (RNase S), and leucine zipper (LZ), which have dissociation constants in the nM range, were studied by native nanoelectrospray mass spectrometry (nanoESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with chemical cross-linking (XL). Complexes interacting with hydrogen bonds survived the transfer into gas phase intact and were observed by nanoESI-MS. Complexes that are bound largely by the hydrophobic effect in solution were not detected or only at very low intensity. Complexes with mixed polar and hydrophobic interactions were detected by nanoESI-MS, most likely due to the contribution from polar interactions. All noncovalent complexes could easily be studied by XL MALDI-MS, which demonstrates that the noncovalently bound complexes are conserved, and a real "snap-shot” of the situation in solution can be obtaine

Phenolic Profile of Grape Canes: Novel Compounds Identified by LC-ESI-LTQ-Orbitrap-MS

Grape canes (Vitis vinifera L.) are a viticulture industry by-product with an important content of secondary metabolites, mainly polyphenols with a broad spectrum of demonstrated health benefits. Grape canes, therefore, have considerable economic potential as a source of high-value phytochemicals. In this work, liquid chromatography coupled with electrospray ionization hybrid linear trap quadrupole-Orbitrap mass spectrometry (LC-LTQ-Orbitrap) was used for the comprehensive identification of polyphenolic compounds in grape canes. Identification of polyphenols was performed by comparing their retention times, accurate mass measured, and mass fragmentation patterns with those of reference substances or available data in the literature. A total of 75 compounds were identified, including phenolic acids, flavanols, flavonols, flavanonols, flavanones, and stilbenoids. The most abundant polyphenols were proanthocyanidins and stilbenoids and their oligomers. Moreover, the high-resolution mass spectrometry analysis revealed the occurrence of 17 polyphenols never described before in grape canes, thereby providing a more complete polyphenolic profile of this potentially valuable by-product

Bench-scale extraction of stilbenoids and other phenolics from stored grape canes (Vitis vinifera): Optimization process, chemical characterization, and potential protection against oxidative damage

Dietary supplements have become the key to complement deficiencies in the occidental diet and therefore to reduce the incidence of oxidative stress related diseases. A bench-scale extraction procedure was studied to obtain a valuable product rich in phenolic compounds and antioxidant capacity from Pinot Noir grape cane enhanced by storage. Extraction solvent, cane-size, solid:liquid ratio, temperature, and extraction time, were systematically evaluated in order to obtain a natural functional product. Complete chemical characterization of a Pinot Noir grape cane extract produced under bench scale process is presented for the first time. Phenolic profiles of the extracts were characterized by HPLC-PDA-MS/MS and minerals by ICP-OES. Proteins, carbohydrates and lignins were also evaluated. The main phenolic compounds in the final product were stilbenoids, flavan-3-ols, procyanidins, and flavonols, with 6.53%, 4.84%, 2.11%, and 0.25%, respectively on a dry matter basis. Other chemical constituents were carbohydrates (27%), minerals (1%) and lignins (38.7%). The antioxidant capacity of the product was demonstrated using chemical assays (TEACABTS/CUPRAC and ORAC-FL) and endothelial cells model. The extract produced under the described bench scale process using grape cane enhanced by storage have a chemical composition and protecting capacities to be used in functional foods industry

Grape cane extracts: an opportunity for the development of novel additives for food Chilean industry

Podeu consultar el III Workshop anual INSA-UB complet a: http://hdl.handle.net/2445/118993Sessió 2. Pòster núm. 1

Encapsulation of Phenolic Compounds from a Grape Cane Pilot-Plant Extract in Hydroxypropyl Beta-Cyclodextrin and Maltodextrin by Spray Drying

Grape canes, the main byproducts of the viticulture industry, contain high-value bioactive phenolic compounds, whose application is limited by their instability and poorly solubility in water. Encapsulation in cyclodextrins allows these drawbacks to be overcome. In this work, a grape cane pilot-plant extract (GCPPE) was encapsulated in hydroxypropyl beta-cyclodextrin (HP-β-CD) by a spray-drying technique and the formation of an inclusion complex was confirmed by microscopy and infrared spectroscopy. The phenolic profile of the complex was analyzed by LC-ESI-LTQ-Orbitrap-MS and the encapsulation efficiency of the phenolic compounds was determined. A total of 42 compounds were identified, including stilbenes, flavonoids, and phenolic acids, and a complex of (epi)catechin with β-CD was detected, confirming the interaction between polyphenols and cyclodextrin. The encapsulation efficiency for the total extract was 80.5 ± 1.1%, with restrytisol showing the highest value (97.0 ± 0.6%) and (E)-resveratrol (32.7 ± 2.8%) the lowest value. The antioxidant capacity of the inclusion complex, determined by ORAC-FL, was 5300 ± 472 µmol TE/g DW, which was similar to the value obtained for the unencapsulated extract. This formulation might be used to improve the stability, solubility, and bioavailability of phenolic compounds of the GCPPE for water-soluble food and pharmaceutical applications

Physical-Chemical Evaluation of Active Food Packaging Material Based on Thermoplastic Starch Loaded with Grape cane Extract

The aim of this paper is to evaluate the physicochemical and microbiological properties of active thermoplastic starch-based materials. The extract obtained from grape cane waste was used as a source of stilbene bioactive components to enhance the functional properties of thermoplastic starch (TPS). The biomaterials were prepared by the compression molding technique and subjected to mechanical, thermal, antioxidant, and microbiological tests. The results showed that the addition of grape cane extract up to 15 wt% (TPS/WE15) did not significantly influence the thermal stability of obtained biomaterials, whereas mechanical resistance decreased. On the other side, among all tested pathogens, thermoplastic starch based materials showed antifungal activity toward Botrytis cinerea and antimicrobial activity toward Staphylococcus aureus, suggesting potential application in food packaging as an active biomaterial layer

Inhibition of Ubc13-mediated ubiquitination by GPS2 regulates multiple stages of B cell development

Non-proteolytic ubiquitin signaling mediated by Lys63 ubiquitin chains plays a critical role in multiple pathways that are key to the development and activation of immune cells. Our previous work indicates that GPS2 (G-protein Pathway Suppressor 2) is a multifunctional protein regulating TNF signaling and lipid metabolism in the adipose tissue through modulation of Lys63 ubiquitination events. However, the full extent of GPS2-mediated regulation of ubiquitination and the underlying molecular mechanisms are unknown. Here, we report that GPS2 is required for restricting the activation of TLR and BCR signaling pathways and the AKT/FOXO1 pathway in immune cells based on direct inhibition of Ubc13 enzymatic activity. Relevance of this regulatory strategy is confirmed in vivo by B cell-targeted deletion of GPS2, resulting in developmental defects at multiple stages of B cell differentiation. Together, these findings reveal that GPS2 genomic and non-genomic functions are critical for the development and cellular homeostasis of B cells

Constructing Memory through Television in Argentina

La televisión representa el pasado reciente de la Argentina a través de vínculos específicos con la memoria social: como un “emprendedor de la memoria” definiendo las agendas públicas, como un vehículo de transmisión intergeneracional sobre el pasado y como un creador de significados por medio de imágenes, sonidos y palabras, esto es, un “escenario para la memoria”. Un análisis de los vínculos entre televisión y memorias, construido alrededor de la desaparición forzada de personas durante la dictadura militar de 1976 a 1983, revela la manera compleja en la cual los obstáculos para relatar ese periodo trágico se combinan con el intento de vender un producto y entretener al espectador.Television represents Argentina’s recent past through three specific links with social memory: as an “entrepreneur of memory,” shaping public agendas, as a vehicle of intergenerational transmission of past events, and as a creator of meaning through images, sounds, and words, a “stage for memory”. An analysis in terms of the links between television and the memories constructed around the forced disappearance of persons during the 1976–1983 military dictatorship reveals the complex way in which the obstacles when narrating an extreme experience are combined with the attempt to sell a product and entertain the spectator.Fil: Feld, Claudia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Sociales. Instituto de Desarrollo Económico y Social. Centro de Investigaciones Sociales; Argentin

Использование голосового интерфейса для взаимодействия пользователя с веб-сервисом

В статье рассмотрены виды существующих интерфейсов взаимодействия пользователя с ЭВМ, приводится сравнительный анализ характеристик интерфейсов. Подробно рассматривается голосовой интерфейс и его использование для взаимодействия пользователя с веб-сервисом

Efficient conditional and promoter-specific in vivo expression of cDNAs of choice by taking advantage of recombinase-mediated cassette exchange using FlEx gene traps

Recombinase-mediated cassette exchange (RMCE) exploits the possibility to unidirectionally exchange any genetic material flanked by heterotypic recombinase recognition sites (RRS) with target sites in the genome. Due to a limited number of available pre-fabricated target sites, RMCE in mouse embryonic stem (ES) cells has not been tapped to its full potential to date. Here, we introduce a universal system, which allows the targeted insertion of any given transcriptional unit into 85 742 previously annotated retroviral conditional gene trap insertions, representing 7013 independent genes in mouse ES cells, by RMCE. This system can be used to express any given cDNA under the control of endogenous trapped promoters in vivo, as well as for the generation of transposon ‘launch pads’ for chromosomal region-specific ‘Sleeping Beauty’ insertional mutagenesis. Moreover, transcription of the gene-of-interest is only activated upon Cre-recombinase activity, a feature that adds conditionality to this expression system, which is demonstrated in vivo. The use of the RMCE system presented in this work requires one single-cloning step followed by one overnight gateway clonase reaction and subsequent cassette exchange in ES cells with efficiencies of 40% in average