These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Reduction of phosphatidylcholine hydroperoxide by apolipoprotein A-I: purification of the hydroperoxide-reducing proteins from human blood plasma.
    Author: Mashima R, Yamamoto Y, Yoshimura S.
    Journal: J Lipid Res; 1998 Jun; 39(6):1133-40. PubMed ID: 9643344.
    Abstract:
    Plasma glutathione peroxidase (GSHPx) has been suggested to reduce submicromolar levels of free fatty acid hydroperoxides and phosphatidylcholine hydroperoxides (PC-OOH), and therefore these hydroperoxides are undetectable in human blood plasma. The capacity for the reduction should be about 2.5 microM as the level of glutathione in human plasma is about 5 microM. However, 2 h of aerobic incubation of 58 microM PC-OOH in human plasma at 37 degrees C resulted in the formation of 36 microM phosphatidylcholine hydroxide (PC-OH). The presence of PC-OOH-reducing protein other than plasma GSHPx was suggested by the results. a) The same rates of PC-OOH decay and PC-OH formation were observed in both sera from rats with selenium-deficient and selenium-supplemented diet; b) the PC-OOH-reducing activity was observed only in the high molecular weight fraction but not in the low molecular weight fraction; and c) albumin did not work as a reducing substrate of plasma GSHPx. We have isolated two hydroperoxide-reducing protein fractions from human plasma by a sequential purification scheme, comprising an ammonium sulfate precipitation followed by sequential chromatography on anion exchange, hydrophobic interaction, and heparin columns. One of the proteins was identified as apolipoprotein A-I by N-terminal amino acid sequence analysis. Moreover, the hydroperoxide-reducing activity of one of the fractions was inhibited almost completely by the addition of anti-apolipoprotein A-I antibody. These findings demonstrate that apolipoprotein A-I in high density lipoprotein can reduce PC-OOH to PC-OH.
    [Abstract] [Full Text] [Related] [New Search]