S-nitrosylated human serum albumin-mediated cytoprotective activity is enhanced by fatty acid binding

J Biol Chem. 2008 Dec 12;283(50):34966-75. doi: 10.1074/jbc.M807009200. Epub 2008 Oct 20.


Binding of oleate to S-nitrosylated human serum albumin (SNO-HSA) enhances its cytoprotective effect on liver cells in a rat ischemia/reperfusion model. It enhances the antiapoptotic effect of SNO-HSA on HepG2 cells exposed to anti-Fas antibody. To identify some of the reasons for the increased cytoprotective effects, additional experiments were performed with glutathione and HepG2 cells. As indicated by 5,5'-dithiobis-2-nitrobenzoic acid binding, the addition of oleate increased the accessibility of the single thiol group of albumin. Binding of increasing amounts of oleate resulted in increasing and more rapid S-transnitrosation of glutathione. Likewise, binding of oleate, or of a mixture of endogenous fatty acids, improved S-denitrosation of SNO-HSA by HepG2 cells. Oleate also enhanced S-transnitrosation by HepG2 cells, as detected by intracellular fluorescence of diaminofluorescein-FM. All of the S-transnitrosation caused by oleate binding was blocked by filipin III. Oleate also increased, in a dose-dependent manner, the binding of SNO-HSA labeled with fluorescein isothiocyanate to the surface of the hepatocytes. A model in two parts was worked out for S-transnitrosation, which does not involve low molecular weight thiols. Fatty acid binding facilitates S-denitrosation of SNO-HSA, increases its binding to HepG2 cells and greatly increases S-transnitrosation by hepatocytes in a way that is sensitive to filipin III. A small nitric oxide transfer takes place in a slow system, which is unaffected by fatty acid binding to SNO-HSA and not influenced by filipin III. Thus, fatty acids could be a novel type of mediator for S-transnitrosation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Dithionitrobenzoic Acid / pharmacology
  • Dose-Response Relationship, Drug
  • Fatty Acids / chemistry*
  • Filipin / chemistry
  • Hepatocytes / metabolism
  • Humans
  • Male
  • Nitric Oxide / chemistry
  • Nitrogen / chemistry*
  • Oleic Acid / chemistry
  • Rats
  • Reperfusion Injury
  • Serum Albumin / chemistry*
  • Sulfhydryl Reagents / pharmacology


  • Fatty Acids
  • Serum Albumin
  • Sulfhydryl Reagents
  • Oleic Acid
  • Nitric Oxide
  • Filipin
  • Dithionitrobenzoic Acid
  • Nitrogen