Characterization of acetohydroxyacid synthase from the hyperthermophilic bacterium Thermotoga maritima

AbstractAcetohydroxyacid synthase (AHAS) is the key enzyme in branched chain amino acid biosynthesis pathway. The enzyme activity and properties of a highly thermostable AHAS from the hyperthermophilic bacterium Thermotoga maritima is being reported. The catalytic and regulatory subunits of AHAS from T. maritima were over-expressed in Escherichia coli. The recombinant subunits were purified using a simplified procedure including a heat-treatment step followed by chromatography. A discontinuous colorimetric assay method was optimized and used to determine the kinetic parameters. AHAS activity was determined to be present in several Thermotogales including T. maritima. The catalytic subunit of T. maritima AHAS was purified approximately 30-fold, with an AHAS activity of approximately 160±27U/mg and native molecular mass of 156±6kDa. The regulatory subunit was purified to homogeneity and showed no catalytic activity as expected. The optimum pH and temperature for AHAS activity were 7.0 and 85°C, respectively. The apparent Km and Vmax for pyruvate were 16.4±2mM and 246±7U/mg, respectively. Reconstitution of the catalytic and regulatory subunits led to increased AHAS activity. This is the first report on characterization of an isoleucine, leucine, and valine operon (ilv operon) enzyme from a hyperthermophilic microorganism and may contribute to our understanding of the physiological pathways in Thermotogales. The enzyme represents the most active and thermostable AHAS reported so far

Induction of Inflammation by West Nile virus Capsid through the Caspase-9 Apoptotic Pathway

West Nile virus (WNV) is a member of the Flaviviridae family of vector-borne pathogens. Clinical signs of WNV infection include neurologic symptoms, limb weakness, and encephalitis, which can result in paralysis or death. We report that the WNV-capsid (Cp) by itself induces rapid nuclear condensation and cell death in tissue culture. Apoptosis is induced through the mitochondrial pathway resulting in caspase-9 activation and downstream caspase-3 activation. Capsid gene delivery into the striatum of mouse brain or interskeletal muscle resulted in cell death and inflammation, likely through capsid-induced apoptosis in vivo. These studies demonstrate that the capsid protein of WNV may be responsible for aspects of viral pathogenesis through induction of the apoptotic cascade

Manufacturing and Supply Chain Flexibility: Building an Integrative Conceptual Model Through Systematic Literature Review and Bibliometric Analysis

The purpose of this study is twofold: first, to establish the current themes on the topic of manufacturing and supply chain flexibility (MSCF), assess their level of maturity in relation to each other, identify the emerging ones and reflect on how they can inform each other, and second, to develop a conceptual model of MSCF that links different themes connect and highlight future research opportunities. The study builds on a sample of 222 articles published from 1996 to 2018 in international, peer-reviewed journals. The analysis of the sample involves two complementary approaches: the co-word technique to identify the thematic clusters as well as their relative standing and a critical reflection on the papers to explain the intellectual content of these thematic clusters. The results of the co-word analysis show that MSCF is a dynamic topic with a rich and complex structure that comprises five thematic clusters. The value chain, capability and volatility clusters showed research topics that were taking a central role in the discussion on MSCF but were not mature yet. The SC purchasing practices and SC planning clusters involved work that was more focused and could be considered more mature. These clusters were then integrated in a framework that built on the competence–capability perspective and identified the major structural and infrastructural elements of MSCF as well as its antecedents and consequences. This paper proposes an integrative framework helping managers keep track the various decisions they need to make to increase flexibility from the viewpoint of the entire value chain

Characterization of the volatile, phenolic and antioxidant properties of monovarietal olive oil obtained from cv. Halhali

Volatile and phenolic compositions of olive oil obtained from the cv. Halhali were investigated in the present study. Fruits were harvested at the optimum maturity stage of ripeness and immediately processed with cold press. Simultaneous distillation/extraction (SDE) with dichloromethane was applied to the analysis of volatile compounds of olive oil. Sensory analysis showed that the aromatic extract obtained by SDE was representative of olive oil odour. In the olive oil, 40 and 44 volatile components were identified and quantified in 2010 and 2012 year, respectively. The total amount of volatile compounds was 18,007 and 19,178 µg kg-1 for 2010 and 2012, respectively. Of these, 11 compounds in the 2010 and 12 in the 2012 harvest presented odour activity values (OAVs) greater than 1, with 1-octen-3-ol, ethyl-3-methyl butanoate, (E)-2-heptenal and (E,Z)-2,4-decadienal being those with the highest OAVs in olive oil. The high-performance liquid chromatographic method coupled with diode-array detection was used to identify and quantify phenolic compounds of the olive oil. A total of 14 phenolic compounds in both years were identified and quantified in olive oil. The major phenolic compounds that were identified in both years were hydroxytyrosol, tyrosol, elenolic acid, luteolin, and apigenin. Antioxidant activity of olive oil was measured using the DPPH and ABTS methods. © 2013 AOCS

Comparative study of bioactive constituents in Turkish olive oils by LC-ESI/MS/MS

The purpose of this research was to evaluate and compare the differences in the phenolic composition, antioxidant properties, and fatty acids of virgin olive oils from the Ayvalik, Gemlik, and Memecik olive varieties cultivated in their respective growing areas over two harvest years. The phenolic composition of olive oils was carried out by liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry analysis and the fatty acid composition was determined by gas chromatography analysis. Fourteen phenolic compounds were identified and, among these, the most dominant were elenolic acid, tyrosol, and hydroxytyrosol. For olives from both years, the highest total phenolic content was determined in Memecik followed by Ayvalik and Gemlik. 2,2-diphenyl-1-picryl hydrazyl and 2,2'-azino-bis-(3-ethyl-benzothiazoline-6-sulphonic acid) methods were used to determine the antioxidant capacity of the olive oil extracts. In both methods, the antioxidant capacity values were higher for oil from cv. Ayvalik. Thirteen fatty acids were identified and quantified in all samples. Oleic acid was the highest concentration and this acid was more dominant in Gemlik oils. © Taylor and Francis Group, LLC.110O602The authors thank the Scientific and Technical Research Council of Turkey (TUBITAK) for financial support for this research project (Project No. 110O602)

Characterization of the key aroma compounds in turkish olive oils from different geographic origins by application of aroma extract dilution analysis (AEDA)

PubMedID: 24387707The aroma and aroma-active compounds of olive oils obtained from Nizip Yaglik (NY) and Kilis Yaglik (KY) cultivars and the effect of the geographical area (southern Anatolian and Aegean regions) on these compounds were analyzed by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). For this purpose, two oil samples were obtained from their native geographical area including NY from Nizip province and KY from Kilis province (southern Anatolian region of Turkey). Another two oils of the same cultivar, NY-Bornova (NY-B) and KY-Bornova (KY-B), were obtained from the Olive Oil Research Center-Bornova, Izmir province (Aegean region of Turkey) to compare geographical effect on aroma and aroma-active compounds. Simultaneous distillation and extraction (SDE) with dichloromethane was used for extraction of volatile components. SDE gave a highly representative aromatic extract of the studied olive oil based on the sensory analysis. Totals of 61, 48, 59, and 48 aroma compounds were identified and quantified in olive oils obtained from NY, NY-B, KY, and KY-B cultivars, respectively. The results of principal component analysis (PCA) showed that the aroma profile of native region oils was discriminately different from those of Bornova region oils. Aldehydes and alcohols were qualitatively and quantitatively the most dominant volatiles in the oil samples. Aroma extract dilution analysis (AEDA) was used for the determination of aroma-active compounds of olive oils. The number of aroma-active compounds in native region oils was higher than in Bornova region oils. Within the compounds, aldehydes and alcohols were the largest aroma-active compounds in all olive oils. © 2013 American Chemical Society

Characterization of potent odorant compounds in Turkish olive oils by GC-MS-olfactometric techniques

The purpose of this study was to determine the most powerful aroma-active compounds of olive oils obtained from Ayvalik (AYV), Gemlik (GEM) and Memecik (MEM) cultivars harvested in 2011, using gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Simultaneous distillation and extraction (SDE) with dichloromethane was used for extraction of volatile components. The aroma- active compounds of olive oils were evaluated by aroma extract dilution analysis (AEDA). A total of 14, 12 and 12 aroma-active compounds within the range of ?64-1024 avor dilution (FD) factors were detected in aromatic extracts of olive oils obtained from AYV, GEM and MEM cvs., respectively. The compounds having the highest FD factor (1024) were (Z)-3-hexenol (cut grass, herbal) and ß- sesquiphellandrene ( oral) for AYV oil and (Z)-3-hexenyl acetate (fruity) for MEM oil. Among these compounds, terpenes were the overwhelmingly largest aroma-active components followed by aldehydes. © 2014 ISEKI-Food Association (IFA).110O602The authors thank the Scientific and Technical Research Council of Turkey (TUBITAK) for financial support for this research project (Project No. 110O602)

GC-MS olfactometric and LC-DAD-ESI-MS/MS characterization of key odorants and phenolic compounds in black dry-salted olives

PubMedID: 29388215BACKGROUND: Olives are processed in different ways depending on consumption habits, which vary between countries. Different de-bittering methods affect the aroma and aroma-active compounds of table olives. This study focused on analyzing the aroma and aroma-active compounds of black dry-salted olives using gas chromatography–mass spectrometry-olfactometry (GC–MS-O) techniques. RESULTS: Thirty-nine volatile compounds which they have a total concentration of 29 459 µg kg-1, were determined. Aroma extract dilution analysis (AEDA) was used to determine key aroma compounds of table olives. Based on the flavor dilution (FD) factor, the most powerful aroma-active compounds in the sample were methyl-2-methyl butyrate (tropical, sweet; FD: 512) and (Z)-3-hexenol (green, flowery; FD: 256). Phenolic compounds in table olives were also analyzed by LC-DAD-ESI-MS/MS. A total of 20 main phenolic compounds were identified and the highest content of phenolic compound was luteolin-7-glucoside (306 mg kg-1), followed by verbascoside (271 mg kg-1), oleuropein (231 mg kg-1), and hydroxytyrosol (3,4-DHPEA) (221 mg kg-1). CONCLUSION: Alcohols, carboxylic acids, and lactones were qualitatively and quantitatively the dominant volatiles in black dry-salted olives. Results indicated that esters and alcohols were the major aroma-active compounds. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industr