14 research outputs found

    Small Angle X-ray Diffraction Study on DOPC+DOPE Liposomes containing Long 1-Alkanols

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    The effect of 1-alkanols (abbreviation CnOH, n = 8-18 is the even number of alkyl carbons) on the transition from lamellar La to inverted hexagonal HII phase of multilamellar dioleylphosphatidylcholine (DOPC) + dioleylphosphatidylethanolamine (DOPE) vesicles at full hydration was studied using small angle X-ray diffraction. For DOPC:DOPE = 1:9 molar ratio the phase transition temperature TBH was observed at ~40°C. The CnOHs studied caused a significant decrease of TBH. The hexagonal phase was observed at presence of shorter alkanols (C8OH – C14OH), at 0.4:1 alkanol:lipid molar ratio, even at 5°C. For C16OH and C18OH the offset of La→ HII transition was detected

    Modulation of sarcoplasmic/endoplasmic reticulum Ca2+-ATPase activity and oxidative modification during the development of adjuvant arthritis

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    Adjuvant arthritis (AA) was induced by intradermal administration of Mycobacterium butyricum to the tail of Lewis rats. In sarcoplasmic reticulum (SR) of skeletal muscles, we investigated the development of AA. SR Ca2+-ATPase (SERCA) activity decreased on day 21, suggesting possible conformational changes in the transmembrane part of the enzyme, especially at the site of the calcium binding transmembrane part. These events were associated with an increased level of protein carbonyls, a decrease in cysteine SH groups, and alterations in SR membrane fluidity. There was no alteration in the nucleotide binding site at any time point of AA, as detected by a FITC fluorescence marker. Some changes observed on day 21 appeared to be reversible, as indicated by SERCA activity, cysteine SH groups, SR membrane fluidity, protein carbonyl content and fluorescence of an NCD-4 marker specific for the calcium binding site. The reversibility may represent adaptive mechanisms of AA, induced by higher relative expression of SERCA, oxidation of cysteine, nitration of tyrosine and presence of acidic phospholipids such as phosphatidic acid. Nitric oxide may regulate cytoplasmic Ca2+ level through conformational alterations of SERCA, and decreasing levels of calsequestrin in SR may also play regulatory role in SERCA activity and expression
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