A new nucleic acid-protein cross-linking reagent.

A new photoactivable reagent is described, which allows the formation of RNA-protein cross-links via disulfide bridges in combination with mercaptobutyrimidate. The reconstituted L24 protein-23S RNA complex from the large subunit of E. coli ribosomes has been used as a model system for the cross-linking. The main advantages of the reagent are the absence of U.V. generated cross-links, since photoactivation is carried out at 360 nm, on one hand and the ease of cleavage of the cross-link by mild reduction (beta-mercaptoethanol) on the other.