Rat spleen glutathione transferases. A new acidic form belonging to the Alpha class.

Cytosolic glutathione transferases (GSTs) were purified from the rat spleen by S-hexyl-GSH-Sepharose chromatography, and two major forms were identified as GSTs 2-2 and 7-7 (GST P). Besides these forms an acidic form (pI 5.8) was purified by chromatofocusing at pH 7-4 and it accounted for about 1% of the total GST activity bound to S-hexyl-GSH-Sepharose. Two-dimensional gel electrophoresis revealed that it is a homodimer (subunit Mr 26,000 with pI 5.8). Immunoblot analysis demonstrated that it was immunologically related to GSTs 2-2 and 1-1, and its N-terminal amino acid was apparently blocked, similarly to other forms of the class Alpha. This form had a low activity towards cumene hydroperoxide or 4-hydroxynon-2-enal, indicating that this form differed from GSTs 10-10 and 8-8 as well as from GSTs 1-1 and 2-2. These results suggest that it is a new form of GST belonging to the class Alpha.