The general purpose of this work is to elucidate the physical basis of molecular genetic phenomena, with emphasis on the properties of nucleic acids and protein-nucleic acid complexes. Specific projects include (a) studies of the conformational transitions of E. coli 5S rRNA, (b) development of psoralen cross-linking and fingerprinting methods to determine the secondary structure of RNA, (c) characterization of nucleosome structure in solution, (d) study of the unfolding of nucleosomes, (e) characterization of the higher order structure of chromatin by transient electric dichroism measurements, (f) study of the interaction of E. coli CAP protein with specific DNA sequences.