Enhancement of acetaldehyde-protein adduct formation by L-ascorbate |
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Authors: | D J Tuma T M Donohue V A Medina M F Sorrell |
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Institution: | Liver Study Unit, The Veterans Administration Medical Center, and The Departments of Internal Medicine and Biochemistry, University of Nebraska Medical Center, Omaha, Nebraska 68105 USA |
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Abstract: | The effect of L-ascorbate on the binding of 14C]acetaldehyde to bovine serum albumin was examined. In the absence of ascorbate, acetaldehyde reacted with albumin to form both unstable (Schiff bases) and stable adducts. Ascorbate (5 mM) caused a time-dependent increase in the formation of total acetaldehyde-albumin adducts, which were comprised mainly of stable adducts. Significant enhancement of adduct formation by ascorbate was observed at acetaldehyde concentrations as low as 5 microM. An ascorbate concentration as low as 0.5 mM was still effective in stimulating stable adduct formation. The electron acceptor, 2,6 dichlorophenolindophenol, prevented the ascorbate-induced increase in albumin-adduct formation. Ascorbate also caused enhanced acetaldehyde adduct formation with other purified proteins, including cytochrome c and histones, as well as the polyamino acid, poly-L-lysine. These results indicate that ascorbate, acting as a reducing agent, can convert unstable acetaldehyde adducts to stable adducts, and can thereby increase and stabilize the binding of acetaldehyde to proteins. |
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Keywords: | To whom correspondence should be addressed at Liver Study Unit Veterans Administration Medical Center 4101 Woolworth Avenue Omaha Neb 68105 |
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