A Glutathione S-transferase Elutes with Glyoxalase-I (Gly-I) During Purification of Gly-I from Maize ( Zea mays L.) Seedlings

Abstract

In this study an attempt was taken to purify Glyoxalase-I (Gly-I: E.C., 4.4.1.5), from maize seedlings. Both green and non-green parts of 7 day old maize seedlings were used as plant materials. Crude proteins were precipitated by 65% (NH4)2SO4, and dialyzed overnight. The dialyzate was applied on DEAE-cellulose chromatography and eluted with linear gradient of KCl from 0 to 0.2 M. In both cases, Gly-I eluted at approximately 85 mM of KCL. The active Gly-I fractions were pooled and applied on a hydroxylapatite chromatography and eluted with 0-40 mM potassium-phosphate buffer, but the eluted fractions showed very poor activity. Therefore, the active pooled fraction of DEAE-chromatography was then applied directly on affinity chromatography (S-hexyl glutathione-agarose) for final purification and eluted with 1.2 mM of S-hexyl glutathione. The purified protein from green and non-green part had specific activity of 33.23 and 39.25 μmol min-1 mg-1 protein, respectively, along with recovery of 1.47 and 162, respectively, and yield of 83.11 and 68.15, respectively. In SDS-PAGE, the active purified affinity fraction was found to move with another protein. The spectrophotometric analysis of high active Gly-I fractions from DEAE-cellulose and affinity chromatography showed GST [another detoxifying enzyme (E.C., 2.5.1.18)] activity. This result suggested that one of the adjacent protein bands in SDS-PAGE was due to presence of a GST in Gly-I fraction.