Chang L H, Wang L Y, Tam M F
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China.
Biochem Biophys Res Commun. 1991 Oct 15;180(1):323-8. doi: 10.1016/s0006-291x(05)81295-1.
Chick liver glutathione S-transferase CL 3-3, expressed using a baculovirus system in Spodoptera frugiperda (SF9) cells, contains a single cysteine residue per subunit. This enzyme was modified with iodoacetamide. Amino acid analysis indicates that 0.85 +/- 0.10 cysteine residue was modified per enzyme subunit. GST CL 3-3 modified with iodo[14C]acetamide was further digested with trypsin and the isotope-labelled fragments were isolated. The fragment containing the cysteine residue accounts for 53% of the total labels. The S-carbaminomethylated protein retains the glutathione conjugating activity. Therefore, the cysteine residue is not essential for the enzymatic activity of CL 3-3.
