BIOCHEMICAL EFFECTS OF SULPHUR DIOXIDE ON PROLINE METABOLISM IN THE ALGA TREBOUXIA SP.

Abstract

SUMMARYCells of the green alga Trebouxia sp. treated with Na2SO3 (5 × 10−5 to 5 × 10−3 M) for 4, 24, 48, and 72 h show a decreased content of proline and an increase in alanine dependent on incubation time and sulphite concentration.The activity of the NAD‐dependent proline dehydrogenase (EC 1.5.1.2, alternative name, pyrroline‐5‐carboxylate reductase) was measured. In vitro sulphite uncompetetively inhibited the enzyme. In vivo, sulphite concentrations up to 5 × 10−4 M led to enhanced enzyme activity.It is suggested that sulphite influences the proline content in Trebouxia via the last enzyme of proline synthesis, proline dehydrogenase.