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Wyszukujesz frazę "urea" wg kryterium: Temat

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    Wyświetlanie 1-4 z 4
    Tytuł:
    Plant ureases: Roles and regulation.
    Autorzy:
    Sirko, Agnieszka
    Brodzik, Robert
    Powiązania:
    https://bibliotekanauki.pl/articles/1044275.pdf
    Data publikacji:
    2000
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    urea
    plants
    nickel
    urease activity
    nitrogen metabolism
    Opis:
    Both urea and urease were subjects of early scientific investigations. Urea was the first organic molecule to be synthesized and jack bean urease was the first enzyme ever to be crystallized. About 50 years later it was shown to be the first nickel metalloenzyme. Since then, nickel-dependent ureases have been isolated from many bacteria, fungi and higher plants. They have similar structures and mechanisms of catalysis. A urease apoenzyme needs to be activated. This process requires participation of several accessory proteins that incorporate nickel into the urease forming catalytic site. In this review, ureases from various organisms are briefly described and the similarities of their structures discussed. Moreover, the significance of urea recycling in plants is explained and recent literature data about the function and activation of plant ureases are presented.
    Źródło:
    Acta Biochimica Polonica; 2000, 47, 4; 1189-1195
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Conformational destabilization of Bacillus licheniformis α-amylase induced by lysine modification and calcium depletion
    Autorzy:
    Tan, Cheau
    Rahman, Raja
    Kadir, Habsah
    Tayyab, Saad
    Powiązania:
    https://bibliotekanauki.pl/articles/1039896.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    salt bridges
    urea
    BLA
    calcium
    lysine
    stability
    conformation
    Opis:
    Bacillus licheniformis α-amylase (BLA) was chemically modified using 100-fold molar excess of succinic anhydride over protein or 0.66 M potassium cyanate to obtain 42 % succinylated and 81 % carbamylated BLAs. Size and charge homogeneity of modified preparations was established by Sephacryl S-200 HR gel chromatography and polyacrylamide gel electrophoresis. Conformational alteration in these preparations was evident by the larger Stokes radii (3.40 nm for carbamylated and 3.34 nm for succinylated BLAs) compared to 2.43 nm obtained for native BLA. Urea denaturation results using mean residue ellipticity (MRE) as a probe also showed conformational destabilization based on the early start of transition as well as ΔGDH2O values obtained for both modified derivatives and Ca-depleted BLA. Decrease in ΔGDH2O value from 5,930 cal/mol (for native BLA) to 3,957 cal/mol (for succinylated BLA), 3,336 cal/mol (for carbamylated BLA) and 3,430 cal/mol for Ca-depleted BLA suggested reduced conformational stability upon modification of amino groups of BLA or depletion of calcium. Since both succinylation and carbamylation reactions abolish the positive charge on amino groups (both α- and ε- amino), the decrease in conformational stability can be ascribed to the disruption of salt bridges present in the protein which might have released the intrinsic calcium from its binding site.
    Źródło:
    Acta Biochimica Polonica; 2011, 58, 3; 405-412
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Conflicting results of non-invasive methods for detection of Helicobacter pylori infection in children with celiac disease - a preliminary study
    Autorzy:
    Józefczuk, Jan
    Mądry, Edyta
    Nowak, Jan
    Walkowiak, Marek
    Łochocka, Klaudia
    Banasiewicz, Tomasz
    Pławski, Andrzej
    Kwiecień, Jarosław
    Walkowiak, Jarosław
    Powiązania:
    https://bibliotekanauki.pl/articles/1038852.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    Helicobacter pylori
    celiac disease
    fecal test
    breath test
    urea
    Opis:
    Background: There are no data addressing the usefulness of non-invasive tests for the detection of Helicobacter pylori (HP) infection in celiac disease (CD). Aim: The aim of this study was to compare two most sensitive and specific tests - urea breath test (UBT) and fecal antigen test (FAT) in HP diagnosis in CD patients. Materials and Methods: The study comprised of 76 CD patients, 49 healthy subjects (HS) and 35 patients who underwent differential diagnosis due to abdominal pain (AP patients). The presence of HP infection was evaluated using the 13C isotope-labeled UBT and FAT (ELISA). Results: HP infection was diagnosed based on UBT and FAT in 8 (16.3%) and 7 (14.3%) HS, and in 8 (10.5%) CD patients and 12 (34.3%) AP patients, respectively, using both tests. The prevalence of conflicting results in comparison with positive results (obtained with any of the two tests) was distinctly higher (54.5%) in CD group than in other subjects (23.3%); however, due to low HP prevalence, it did not reach the level of significance (p<0.1759). Conclusion: CD may increase the risk of divergent results of non-invasive tests used for the detection of HP infection in children. Since UBT is the most reliable test, we suggest its standard use as a method of choice in pediatric CD - at least until new evidence emerges supporting a different approach.
    Źródło:
    Acta Biochimica Polonica; 2016, 63, 1; 127-130
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A 2D-IR study of heat- and [13C]urea-induced denaturation of sarcoplasmic reticulum Ca2+-ATPase.
    Autorzy:
    Iloro, Ibón
    Goñi, Félix
    Arrondo, José
    Powiązania:
    https://bibliotekanauki.pl/articles/1041432.pdf
    Data publikacji:
    2005
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    2D-IR
    urea-induced denaturation
    sarcoplasmic reticulum
    heat-induced denaturation
    Opis:
    Two-dimensional infrared correlation spectroscopy (2D-IR) was applied to the study of urea- and heat-induced unfolding denaturation of sarcoplasmic reticulum Ca^(2+)-ATPase (SR ATPase). Urea at 2-3 M causes reversible loss of SR ATPase activity, while higher concentrations induce irreversible denaturation. Heat-induced denaturation is a non-two-state process, with an "intermediate state" (at t ≈ 45°C) characterized by the presence of protein monomers, instead of the native oligomers. 2D-IR reveals that urea denaturation causes loss of the structural transition to the "intermediate state". Whenever the urea effect can be reversed, the transition to the "intermediate state" is re-established.
    Źródło:
    Acta Biochimica Polonica; 2005, 52, 2; 477-483
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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