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: Protein L-dopa as an index of hydroxyl radical attack on protein tyrosine.
    Author: Cohen G, Yakushin S, Dembiec-Cohen D.
    Journal: Anal Biochem; 1998 Oct 15; 263(2):232-9. PubMed ID: 9799536.
    Abstract:
    It is widely believed that hydroxyl radicals generated in vivo contribute to damage to macromolecules, such as proteins and DNA. We evaluated methodology based on the transformation of protein tyrosine to L-Dopa, via aromatic ring hydroxylation, as an index of hydroxyl radical attack on proteins. The catechol structure of Dopa makes it amenable to isolation with alumina, followed by HPLC analysis, typically used for the measurement of catecholamines. Because a level of controversy exists about the formation of Dopa by hydroxyl radicals, we conducted a systematic study of the formation of Dopa from tyrosine, tyrosine dipeptides, pure proteins (chymotrypsin and myelin basic protein), and endogenous proteins in tissue homogenates (rat brain), exposed to hydroxylating conditions (Fe2+/EDTA/ascorbate at neutral pH). Dopa residues in peptides and proteins were liberated by acid hydrolysis with 6 M HCl at 145 degrees C for 1 h. A marked lability of Dopa in 6 M HCl under hydrolysis conditions was prevented with added phenol; chymotrypsin and precipitated pellets of brain protein were also protective. Overall recoveries (hydrolysis plus purification procedures) averaged 83.4 +/- 1.7%. This improved analytic procedure may be useful for studying protein damage by hydroxyl radicals.
    [Abstract] [Full Text] [Related] [New Search]