Effect of sulfur‐dioxide on protein‐SH in needles of Picea abies¹

The effect of SO 2 on the SH‐groups of proteins in needles of Picea abies is studied. The content of total protein SH and glutathione is estimated with 5.5′‐Dithio‐bis‐nitrobenzoic‐acid (Ellman reagent). In addition structural protein SH is measured microspectrophotometrically in sections stained with the SH reagent, mercurochrome. The results indicate that GSH and also total protein SH and structural protein SH are increased in needles of Picea abies growing in SO 2 polluted areas. Compared to needles of trees in relatively unpolluted areas average increases of 2. 33 (GSH), 1.22 (total protein SH) and 1.55 (structural protein SH) are found.