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    Wyświetlanie 1-4 z 4
    Tytuł:
    Non-random base composition in codons of mitochondrial cytochrome b gene in vertebrates.
    Autorzy:
    Prusak, Beata
    Grzybowski, Tomasz
    Powiązania:
    https://bibliotekanauki.pl/articles/1041499.pdf
    Data publikacji:
    2004
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    structure-function relationships
    compositional bias
    cytochrome b
    Opis:
    Cytochrome b is the central catalytic subunit of the quinol:cytochrome c oxidoreductase of complex III of the mitochondrial oxidative phosphorylation system and is essential to the viability of most eukaryotic cells. Partial cytochrome b gene sequences of 14 species representing mammals, birds, reptiles and amphibians are presented here including some species typical for Poland. For the analysed species a comparative analysis of the natural variation in the gene was performed. This information has been used to discuss some aspects of gene sequence - protein function relationships. Review of relevant literature indicates that similar comparisons have been made only for basic mammalian species. Moreover, there is little information about the Polish-specific species. We observed that there is a strong non-random distribution of nucleotides in the cytochrome b sequence in all tested species with the highest differences at the third codon position. This is also the codon position of the strongest compositional bias. Some tested species, representing distant systematic groups, showed unique base composition differing from the others. The quail, frog, python and elk prefer C over A in the light DNA strand. Species belonging to the artiodactyls stand out from the remaining ones and contain fewer pyrimidines. The observed overall rate of amino acid identity is about 61%. The region covering Qo center as well as histidines 82 and 96 (heme ligands) are totally conserved in all tested species. Additionally, the applied method and the sequences can also be used for diagnostic species identification by veterinary and conservation agencies.
    Źródło:
    Acta Biochimica Polonica; 2004, 51, 4; 897-905
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the mode of integration of the thylakoid membrane protein cytochrome b6 into cytoplasmic membrane of Escherichia coli
    Autorzy:
    Króliczewski, Jaroslaw
    Gubernator, Beata
    Rögner, Matthias
    Szczepaniak, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/1039882.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    membrane protein
    signal sequence
    integration/translocation
    cytochrome b6
    Opis:
    In the stroma compartment, several pathways are used for integration/translocation of chloroplast proteins into or across the thylakoid membrane. In this study we investigated the mode of incorporation of the chloroplast-encoded cytochrome b6 into the bacterial membrane. Cytochrome b6 naturally comprises of four transmembrane helices (A,B,C,D) and contains two b-type hemes. In the present study, mature cytochrome b6 or constructed deletion mutants of cytochrome were expressed in E. coli cells. The membrane insertion of cytochrome b6 in this bacterial model system requires an artificially added presequence that directs the protein to use an E. coli membrane-insertion pathway. This could be accomplished by fusion to maltose-binding protein (MBP) or to the bacterial Sec-dependent signal peptide (SSpelB). The integration of mature cytochrome b6 into the bacterial cytoplasmic membrane by the Sec pathway has been reported previously by our group (Kroliczewski et al., 2005, Biochemistry, 44: 7570). The results presented here show that cytochrome b6 devoid of the first helix A can be inserted into the membrane, as can the entire ABCD. On the other hand, the construct devoid of helices A and B is translocated through the membrane into the periplasm without any effective insertion. This suggests the importance of the membrane-anchoring sequences that are likely to be present in only the A and B part, and it is consistent with the results of computational prediction which did not identify any membrane-anchoring sequences for the C or D helices. We also show that the incorporation of hemes into the truncated form of cytochrome b6 is possible, as long as the B and D helices bearing axial ligands to heme are present.
    Źródło:
    Acta Biochimica Polonica; 2011, 58, 3; 335-343
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Expression of cytochrome CYP2B1/2 in nonpregnant, pregnant and fetal rats exposed to tobacco smoke.
    Autorzy:
    Czekaj, Piotr
    Wiaderkiewicz, Anna
    Florek, Ewa
    Wiaderkiewicz, Ryszard
    Powiązania:
    https://bibliotekanauki.pl/articles/1044235.pdf
    Data publikacji:
    2000
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    pregnancy
    CYP2B6
    rats
    cytochrome P450
    CYP2B1/2
    tobacco smoke
    Opis:
    Four-month-old female Wistar rats were exposed for 20 days to tobacco smoke obtained from non-filter cigarettes. During the exposure, concentration of tobacco smoke was monitored indirectly by measuring the CO level (1500 mg/m3 air). The efficacy of exposure was assessed by measuring urine nicotine and cotinine levels. Cigarette smoke did not change total cytochrome P450 and b5 protein levels in any of the organs studied, and most of these organs did not show any changes in the activity of reductases associated with these cytochromes. Following exposure to tobacco smoke, fetal rat liver expressed CYP2B1/2 protein; in newborns (day 1) both liver and lung showed CYP2B1/2 protein expression and very low pentoxyresorufin O-dealkylase activity. Western blot analysis of adult liver, lung, heart, but not of brain microsomes, showed that tobacco smoke induced CYP2B1/2 in both nonpregnant and pregnant rats, though its expression was lower in the livers and hearts of pregnant females. In the rat and human placenta, neither rat CYP2B1/2 nor human CYP2B6 showed basal or tobacco smoke-induced expression at the protein level. This study shows clearly that the expression of CYP2B1/2, which metabolizes nicotine and some drugs and activates carcinogens, is controlled in rats by age-, pregnancy-, and tissue-specific regulatory mechanisms.
    Źródło:
    Acta Biochimica Polonica; 2000, 47, 4; 1115-1127
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Phenobarbital-induced expression of cytochrome P450 genes.
    Autorzy:
    Czekaj, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/1044233.pdf
    Data publikacji:
    2000
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    CYP2B
    cytochrome P450
    phenobarbital-responsive enhancer unit
    CYP2H1.
    orphan receptors
    CYP3A
    PXR
    CAR
    phenobarbital
    Opis:
    In contrast to the well-known Ah receptor-mediated regulation of the CYP1A1 gene by polycyclic aromatic hydrocarbons, the molecular mechanism by which phenobarbital (PB) and PB-like inducers affect transcription of CYP genes remains unknown; no receptor for these chemicals has been found to date. However, in the last 5 years PB-responsive sequences have been identified in the 5' flanking regions of several P450 genes. The phenobarbital-responsive enhancer unit (PBRU) of CYP2B gene family members contain two potential nuclear receptor binding sites (NR1 and NR2) that flank a nuclear factor 1 (NF-1) binding motif. The nuclear factors that regulate PBRU activity have not yet been characterized. It seems that PB may activate multiple nuclear orphan receptors to induce various CYP genes. CYP2B and CYP3A genes appear to be targets for the orphan receptors CAR and PXR, respectively. It is also possible that the pleiotropic effects of PB can, in part, be explained by the ability of the CAR-RXR heterodimer to bind to a variety of nuclear receptor binding motifs. The induction of cytochromes P450 may result in interactions between xenobiotics and in the interference of xenobiotic metabolism and endogenous signalling pathways.
    Źródło:
    Acta Biochimica Polonica; 2000, 47, 4; 1093-1105
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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