Nucleic acids-protein interactions: structural studies by x-ray diffraction and model building.

X-ray diffraction and model-building studies suggest that the alpha-helix and beta-structure of protein may interact with double-helix nucleic acids. In the former case basic side chains of amino acid residues in the alpha-helix can interact with phosphate groups of the double helix, and in the latter case the peptide backbone in a beta-ribbon can hydrogen-bond to the backbone of the double helix of nucleic acids. These structurally compatible interactions between well-known secondary structures of protein and the double helix provide models for understanding specific interaction between nucleic acid and protein during general recognition, or preliminary stages before base sequence-specific recognition.