Diethyl pyrocarbonate inactivation of human placental aldehyde reductase II

Aruni Bhatnagar, Ballabh Das, Satish K. Srivastava

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    Abstract

    Diethyl pyrocarbonate inactivated aldehyde reductase II (l-gulonate: NADP+ 6-oxidoreductase, EC 1.1.1.19) from human placenta. A concentration of 0.5-1.0 mM diethyl pyrocarbonate caused 40-65% loss of activity. The inactivation of the enzyme by diethyl pyrocarbonate was reversed by hydroxylamine and was accompanied by a large change in the absorbance of the protein at 242 nm, but not at 278 nm, indicating that only the histidine residues were modified. NADPH, but not glucoronate afforded significant protection to the enzyme from inactivation by diethyl pyrocarbonate. With 0.2-1.0 mM diethyl pyrocarbonate, 4-5 histidine residues were modified with a pseudo-first-order rate process. A double log plot of the fraction of the unmodified residues indicates that only one functional histidine residue is essential for the catalytic activity of aldehyde reductase II.

    Original languageEnglish
    Pages (from-to)179-184
    Number of pages6
    JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
    Volume916
    Issue number2
    DOIs
    StatePublished - Nov 26 1987

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    Keywords

    • (Human placenta)
    • Active site
    • Aldehyde reductase II
    • Diethyl pyrocarbonate
    • Enzyme inactivation

    ASJC Scopus subject areas

    • Biochemistry
    • Biophysics
    • Molecular Biology
    • Structural Biology

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