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  1. Article ; Online: On the Protein Fibrillation Pathway

    Jelica Milošević / Radivoje Prodanović / Natalija Polović

    Molecules, Vol 26, Iss 4, p

    Oligomer Intermediates Detection Using ATR-FTIR Spectroscopy

    2021  Volume 970

    Abstract: Oligomeric intermediates on the pathway of amyloid fibrillation are suspected as the main cytotoxins responsible for amyloid-related pathogenicity. As they appear to be a part of the lag phase of amyloid fibrillation when analyzed using standard methods ... ...

    Abstract Oligomeric intermediates on the pathway of amyloid fibrillation are suspected as the main cytotoxins responsible for amyloid-related pathogenicity. As they appear to be a part of the lag phase of amyloid fibrillation when analyzed using standard methods such as Thioflavin T (ThT) fluorescence, a more sensitive method is needed for their detection. Here we apply Fourier transform infrared spectroscopy (FTIR) in attenuated total reflectance (ATR) mode for fast and cheap analysis of destabilized hen-egg-white lysozyme solution and detection of oligomer intermediates of amyloid fibrillation. Standard methods of protein aggregation analysis— Thioflavin T (ThT) fluorescence, atomic force microscopy (AFM), and 8-anilinonaphthalene-1-sulphonic acid (ANS) fluorescence were applied and compared to FTIR spectroscopy data. Results show the great potential of FTIR for both, qualitative and quantitative monitoring of oligomer formation based on the secondary structure changes. While oligomer intermediates do not induce significant changes in ThT fluorescence, their secondary structure changes were very prominent. Normalization of specific Amide I region peak intensities by using Amide II peak intensity as an internal standard provides an opportunity to use FTIR spectroscopy for both qualitative and quantitative analysis of biological samples and detection of potentially toxic oligomers, as well as for screening of efficiency of fibrillation procedures.
    Keywords ATR FTIR ; oligomer intermediates ; amyloid fibrillation ; HEWL ; secondary structure perturbation ; Organic chemistry ; QD241-441
    Subject code 540 ; 500
    Language English
    Publishing date 2021-02-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: Tyramine-modified pectins via periodate oxidation for soybean hull peroxidase induced hydrogel formation and immobilization

    Prokopijevic, Milos / Olivera Prodanovic / Dragica Spasojevic / Gordana Kovacevic / Natalija Polovic / Ksenija Radotic / Radivoje Prodanovic

    Applied microbiology and biotechnology. 2017 Mar., v. 101, no. 6

    2017  

    Abstract: Pectin was modified by oxidation with sodium periodate at molar ratios of 2.5, 5, 10, 15 and 20 mol% and reductive amination with tyramine and sodium cyanoborohydride afterwards. Concentration of tyramine groups within modified pectin ranged from 54.5 ... ...

    Abstract Pectin was modified by oxidation with sodium periodate at molar ratios of 2.5, 5, 10, 15 and 20 mol% and reductive amination with tyramine and sodium cyanoborohydride afterwards. Concentration of tyramine groups within modified pectin ranged from 54.5 to 538 μmol/g of dry pectin while concentration of ionizable groups ranged from 3.0 to 4.0 mmol/g of dry polymer compared to 1.5 mmol/g before modification due to the introduction of amino group. All tyramine-pectins showed exceptional gelling properties and could form hydrogel both by cross-linking of carboxyl groups with calcium or by cross-linking phenol groups with peroxidase in the presence of hydrogen peroxide. These hydrogels were tested as carriers for soybean hull peroxidase (SHP) immobilization within microbeads formed in an emulsion based enzymatic polymerization reaction. SHP immobilized within tyramine-pectin microbeads had an increased thermal and organic solvent stability compared to the soluble enzyme. Immobilized SHP was more active in acidic pH region and had slightly decreased K ₘ value of 2.61 mM compared to the soluble enzyme. After 7 cycles of repeated use in batch reactor for pyrogallol oxidation microbeads, immobilized SHP retained half of the initial activity.
    Keywords calcium ; crosslinking ; emulsions ; gelling properties ; hydrogels ; hydrogen peroxide ; microbeads ; oxidation ; pH ; pectins ; peroxidase ; polymerization ; polymers ; pyrogallol ; solvents ; soybean hulls ; tyramine
    Language English
    Dates of publication 2017-03
    Size p. 2281-2290.
    Publishing place Springer Berlin Heidelberg
    Document type Article
    ZDB-ID 392453-1
    ISSN 1432-0614 ; 0171-1741 ; 0175-7598
    ISSN (online) 1432-0614
    ISSN 0171-1741 ; 0175-7598
    DOI 10.1007/s00253-016-8002-x
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 79/727: Show issues

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  3. Article: Optimizing storage conditions to prevent cold denaturation of trypsin for sequencing and to prolong its shelf life

    Rašković, Brankica / Boban Anđelković / Natalija Polović / Saša Vatić / Vladimir Blagojević

    Biochemical engineering journal. 2016 Jan. 15, v. 105

    2016  

    Abstract: Trypsin is a serine protease with widespread applications, including protein sequencing and trypsin mass fingerprinting. In the present study, the storage of trypsin in acidic conditions significantly affected the recovery of activity (40%) after 7 ... ...

    Abstract Trypsin is a serine protease with widespread applications, including protein sequencing and trypsin mass fingerprinting. In the present study, the storage of trypsin in acidic conditions significantly affected the recovery of activity (40%) after 7 freeze–thaw cycles. Further, trypsin lost parts of its native secondary structure elements, which resulted in a 10% increase in β-sheet content (band maximum detected at a frequency of 1634cm−1 in the Fourier transform infrared (FT-IR) spectrum) indicative of freezing-induced denaturation of the protein. The cold storage of trypsin in ammonium bicarbonate (pH 8.2) with the addition of cryoprotectants, such as glycerol or lysine, led to protein stabilization (complete secondary structure content preservation was detected by FT-IR), higher activity recovery (>90%) and modest autolysis (<10%). High activity recovery (>90%) was also detected with the addition of propylene glycol and polyethylene glycol, saccharides and arginine. Nevertheless, trypsin stored at pH 8.2 with the addition of glycerol or lysine was as efficient as untreated trypsin in the trypsin mass fingerprinting analysis of BSA, suggesting that the cold storage of trypsin in slightly alkaline conditions with the addition of cryoprotectants could prolong its shelf life.
    Keywords ammonium bicarbonate ; arginine ; autolysis ; cold ; cold storage ; cryoprotectants ; denaturation ; Fourier transform infrared spectroscopy ; freeze-thaw cycles ; glycerol ; lysine ; pH ; polyethylene glycol ; propylene glycol ; protein denaturation ; shelf life ; storage conditions ; trypsin
    Language English
    Dates of publication 2016-0115
    Size p. 168-176.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 2012139-8
    ISSN 1369-703X
    ISSN 1369-703X
    DOI 10.1016/j.bej.2015.09.018
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  4. Article ; Online: Pseudomonas aeruginosa quorum sensing inhibition by clinical isolate Delftia tsuruhatensis 11304

    Milka Malešević / Flaviana Di Lorenzo / Brankica Filipić / Nemanja Stanisavljević / Katarina Novović / Lidija Senerovic / Natalija Polović / Antonio Molinaro / Milan Kojić / Branko Jovčić

    Scientific Reports, Vol 9, Iss 1, Pp 1-

    involvement of N-octadecanoylhomoserine lactones

    2019  Volume 13

    Abstract: Abstract Pseudomonas aeruginosa is one of the most common opportunistic pathogens that use quorum sensing (QS) system to regulate virulence factors expression and biofilm development. Delftia sp. 11304 was selected among 663 Gram-negative clinical ... ...

    Abstract Abstract Pseudomonas aeruginosa is one of the most common opportunistic pathogens that use quorum sensing (QS) system to regulate virulence factors expression and biofilm development. Delftia sp. 11304 was selected among 663 Gram-negative clinical isolates based on its QS inhibitory activity against P. aeruginosa MMA83 clinical isolate. Whole genome sequencing identified this isolate as D. tsuruhatensis and revealed genetic armamentarium of virulence factors and antibiotic resistance determinants. Ethyl acetate extract of D. tsuruhatensis 11304 culture supernatant (QSI extract) prevented biofilm formation of P. aeruginosa MMA83, but was unable to cause biofilm decomposition. QSI extract showed a synergistic effect in combination with meropenem and gentamycin, against P. aeruginosa MMA83. A dose-dependent reduction of the virulence factors: elastase, rhamnolipid and pyocyanin production by P. aeruginosa MMA83 and significant downregulation of lasI, lasR, rhlI, rhlR, pqs and mvfR expression were observed. Matrix-assisted Laser Desorption Ionization (MALDI) mass spectrometry of D. tsuruhatensis 11304 QSI extract revealed the presence of N-acyl homoserine lactones (AHL) with chain lengths of C12 to C18. The main ion peak was identified as N-octadecanoylhomoserine lactone (C18-HSL). Commercial C18-HSL (20 µM) reduced pyocyanin production as well as mRNA level of the lasI gene. A novel AHL species, dihydroxy-N-octadecanoylhomoserine lactone, was also described.
    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2019-11-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Identification, purification and characterization of a novel collagenolytic serine protease from fig (Ficus carica var. Brown Turkey) latex

    Raskovic, Brankica / Natalija Polovic / Olga Bozovic / Radivoje Prodanovic / Vesna Niketic

    The Society for Biotechnology, Japan Journal of bioscience and bioengineering. 2014 Dec., v. 118

    2014  

    Abstract: A novel collagenolytic serine protease was identified and then purified (along with ficin) to apparent homogeneity from the latex of fig (Ficus carica, var. Brown Turkey) by two step chromatographic procedure using gel and covalent chromatography. The ... ...

    Abstract A novel collagenolytic serine protease was identified and then purified (along with ficin) to apparent homogeneity from the latex of fig (Ficus carica, var. Brown Turkey) by two step chromatographic procedure using gel and covalent chromatography. The enzyme is a monomeric protein of molecular mass of 41 ± 9 kDa as estimated by analytical gel filtration chromatography. It is an acidic protein with a pI value of approximately 5 and optimal activity at pH 8.0–8.5 and temperature 60°C. The enzymatic activity was strongly inhibited by PMSF and Pefabloc SC, indicating that the enzyme is a serine protease. The enzyme showed specificity towards gelatin and collagen (215 GDU/mg and 24.8 CDU/mg, respectively) and non-specific protease activity (0.18 U/mg against casein). The enzyme was stable and retained full activity over a broad range of pH and temperature. The fig latex collagenolytic protease is potentially useful as a non-microbial enzyme with collagenolytic activity for various applications in the fields of biochemistry, biotechnology and medicine.
    Keywords biotechnology ; casein ; collagen ; enzyme activity ; enzyme stability ; ficain ; Ficus carica ; figs ; gel chromatography ; gelatin ; isoelectric point ; latex ; medicine ; molecular weight ; pH ; serine proteinases ; temperature
    Language English
    Dates of publication 2014-12
    Size p. 622-627.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 1465387-4
    ISSN 1347-4421 ; 1389-1723
    ISSN (online) 1347-4421
    ISSN 1389-1723
    DOI 10.1016/j.jbiosc.2014.05.020
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    In stock of ZB MED Bonn / Germany

    Z 4728: Show issues

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