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Inhibition of glutathione transferase pi from human placenta by 1-chloro-2,4-dinitrobenzene occurs because of covalent reaction with cysteine 47.
- Source :
-
Archives of biochemistry and biophysics [Arch Biochem Biophys] 1992 Aug 15; Vol. 297 (1), pp. 119-22. - Publication Year :
- 1992
-
Abstract
- Human placenta glutathione transferase pi is irreversibly inhibited when incubated with 1-chloro-2,4-dinitrobenzene (CDNB) in the absence of the cosubstrate glutathione. The enzyme is protected against CDNB inactivation by the presence of S-methylglutathione and glutathione. The kinetics of inactivation is pseudo-first-order with k(obs) = 0.04 min-1 when 44 microM enzyme is incubated in presence of 1 mM CDNB at pH 6.5. The inhibition is saturable with respect to the CDNB concentration and the enzyme-CDNB complex shows a K(i) = 2.7 mM. Concomitant to the inhibition process is formation of an absorption band at 340 nm. After trypsin digestion and HPLC analysis, the CDNB-reacted enzyme gives a single peptide absorbing at 340 nm. Automated Edman degradation of this peptide indicates cysteine 47 to be the residue alkylated by CDNB.
Details
- Language :
- English
- ISSN :
- 0003-9861
- Volume :
- 297
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Archives of biochemistry and biophysics
- Publication Type :
- Academic Journal
- Accession number :
- 1637174
- Full Text :
- https://doi.org/10.1016/0003-9861(92)90648-g