SELENIUM-CONTAINING PEROXIDASES OF GERMINATING BARLEY

Germinating barley grown on an artificial medium was exposed to Se-75- selenite for 8 d. Then the leaves were homogenized and proteins were s eparated by means of Sephadex G-150 filtration, followed by DEAE-Sepha rose chromatography. Each fraction collected was assayed for total pro tein, radioactivity, and peroxidase activity. In barley leaves, three protein peaks (peaks no. I, II, and III) with peroxidase activity coul d be separated by Sephadex G 150 filtration. Each fraction was then fu rther separated on DEAE-Sepharose chromatography. Thus, peaks I and II were resolved by DEAE-Sepharose into one major and two minor peaks of radioactivity. However, only the major peak showed peroxidase activit y. Peak III was resolved from the gel filtration on the DEAE-sepharose into one major and four minor peaks of radioactivity. The major and t hree of the minor radioactivity peaks contained peroxidase activity Th e protein fractions were separated by polyacrylamide gel electrophores is. The molecular weights of separated proteins were estimated by mean s of molecular markers, and Se-75 radioactivity was evaluated by autor adiography. Thus, gel filtration peak I contained four bands with mol wts of 128, 116, 100, and 89 kDa. Of these, the 89 kDa protein contain ed selenium. Peak II contained three protein bands with mol wts 79.4, 59.6, and 59.9. The 59.6 band was a selenoprotein. Peak III contained four protein bands (and some very weak bands). The four major bands ha d mol wts of 38.6, 31.6, 30.2, and 29.2 kDa. The last mentioned band w as a selenoprotein.