Evidence for the ultraviolet‐B (280–320 nm) radiation induced structural reorganization and damage of photosystem II polypeptides in isolated chloroplasts

Direct evidence for the possible loss of photosystem II (PS II) activity in chloroplasts of Vigna sinensis L. cv. Walp after ultraviolet‐B (UV‐B, 280–320 nm) radiation treatment was provided by polyacrylamide gel electrophoretic analysis of PS II polypeptides. A 30 min UV‐B treatment of chloroplasts caused a 50% loss of PS II activity. The artificial electron donor. Mn 2+ failed to restore UV‐B radiation induced loss of PS II activity, while diphenyl carbazide (DPC) and NH 2 OH only partially restored activity. Such a loss in PS II activity was found to be primarily due to a loss of 23 and 33 kDa extrinsic polypeptides. UV‐B treatment induced the synthesis of a few polypeptides and a 29 kDa light‐harvesting chlorophyll protein.