Nitrite, hydroxylamine and sulphite reductases in wheat leaves

Abstract

The inclusion of cysteine and Na-EDTA in the extracting buffer lowered the activity of sulphite reductase extracted from wheat leaves while nitrite and hydroxylamine reductases were not so affected. Maximum activity for the three enzymes was achieved with reduced methyl viologen as the electron donor. The three enzyme activities were found in the chloroplasts. Nitrite reductase was detected in the leaves of the seedlings only when grown with nitrate and exposed to light. Sulphite and hydroxylamine reductases were not, however, influenced by either of these treatments. These results suggest that nitrite reductase is a distinct enzyme and is not associated with sulphite reductase and hydroxylamine reductase in wheat leaves.