Effects of Ultraviolet Radiation on the Plasma Membranes of Chava corallina. III* Action Spectra

Abstract

Action spectra have been determined for the effects of 300 s of U.V. irradiation on the potential difference and conductance of the plasmalemma in cells of C, couallina. Wavelengths for maximum effect were 240-2.50 nm and 285 nm. The target molecules are tentatively identified as protein molecules containing vulnerable amino acids such as cystine, since this has high photochemical lability to 250-nm U.V. Absorption at 285 nm could be by aromatic amino acids in the same or different proteins. A schematic model for the various u.v.-sensitive membrane properties is given, based on the fluid mosaic model of cell membranes.