Characterization of the basic glutathione S-transferase B1 and B2 subunits from human liver.
The basic glutathione S-transferases in human liver are composed of at least two immunochemically distinct polypeptides, designated B1 and B2. These subunits exist as homodimers, but can hybridize to form the B1B2 heterodimer [Stockman, Beckett & Hayes (1985) Biochem. J. 227, 457-465]. Although these basic glutathione S-transferases possess similar catalytic properties, the B2 subunit exhibits significantly greater selenium-independent glutathione peroxidase activity than subunit B1. The use of the ligands haematin, tributyltin acetate and Bromosulphophthalein as inhibitors of 1-chloro-2,4-dinitrobenzene-GSH-conjugating activity clearly discriminate between the B1 and B2 subunits and should help facilitate their identification. Peptide mapping experiments showed that B1 and B2 are structurally distinct, but related, subunits; subunit B1 yielded 43 tryptic peptides, seven of which were unique, whereas subunit B2 yielded 40 tryptic peptides, four of which were unique.
Stockman
P K
PK
University of Edinburgh Department of Clinical Chemistry, Royal Infirmary, Scotland, U.K.
McLellan
L I
LI
Hayes
J D
JD
D000596:Amino Acids / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000302:isolation & purification*; D008099:Liver / Q000201:enzymology*; D010449:Peptide Mapping; D013379:Substrate Specificity
D000596:Amino Acids; D007527:Isoenzymes; D005982:Glutathione Transferase