Interactions of Biological Macromolecules Visualized by X-ray Crystallography
Abstract Biologically important macromolecules, which principally include proteins and nucleic acids, are polymers of small building block molecules. These are amino acids for proteins, of which there are twenty, and nucleotides, four in number, for nucleic acids. Proteins comprise the major classes of enzymes that catalyze and regulate metabolism, movement and development while nucleic acids, DNA and RNA serve as the reservoir of genetic material as well as provide a means for its expression. In order to completely understand the chemical and physical mechanisms by which these strategic cellular components function, a description of their structure at the atomic level is essential. The only technique currently available for visualizing the structures of macromolecules is X-ray diffraction analysis of single crystals of proteins and nucleic acids. Application of the technique requires the measurement of hundreds of thousands of diffraction intensities from both native and heavy atom modified crystals, the...