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Interaction of thioredoxin with oxidized aminobutyrate aminotransferase Evidence for the formation of a covalent intermediate
Author(s) -
Park Joohong,
Churchich Jorge E.
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)81132-6
Subject(s) - covalent bond , thioredoxin , dimer , chemistry , enzyme , biochemistry , substrate (aquarium) , pyrroloquinoline quinone , thioredoxin reductase , stereochemistry , cofactor , organic chemistry , biology , ecology
Pig brain 4‐aminobutyrate aminotransferase is inactivated by pre‐incubation with pyrroloquinoline quinone (2,7,9‐tricarboxy‐1H‐pyrrolo[2,3,f]quinoline‐4,5‐dione; PQQ) at pH 7. The reaction of approximately 2 SH residues/dimer is sufficient to inactivate the enzyme. Reoxidized aminotransferase is reactivated by E. coli thioredoxin. Similar results were obtained with E. coli 4‐aminobutyrate aminotransferase. The spectroscopic properties of thioredoxin, tagged with the fluorescence probe, anthraniloyl, were used to monitor its interaction with re‐oxidized 4‐aminobutyrate aminotransferase. During the regeneration of native aminotransferase by thioredoxin, the substrate forms a covalent intermediate with the oxireductase, as revealed by gel filtration chromatography. It is postulated that the substrate (oxidized aminotransferase) forms a covalent intermediate with thioredoxin through disulfide linkages.