Abstract
Calf lens protein was irradiated with near ultraviolet (UV) light in the presence of the drugs chlorpromazine, promazine, and hematoporphyrin. It then was analyzed by SDS-polyacrylamide gel electrophoresis and amino acid analysis. Marked increases in protein photopolymerization (other than S-S bond formation) and histidine destruction were noted in the presence of these drugs. In all cases, these effects were reduced in the presence of a singlet oxygen quencher, thus suggesting that these photodynamic effects are due, at least in part, to a Type II mechanism.