Nitration of Tyrosine Residues in Protein-Nucleic Acid Complexes

Abstract

Chemical modification is a powerful tool for investigating the accessibility and function of specific amino acids within folded proteins. It has provided significant information regarding the role of different amino acids at the binding sites of numerous enzymes and DNA-binding proteins. The identification of such residues by chemical modification has then often be used to plan subsequent site-directed mutagenesis experiments. These data complement those from crystallographic and nuclear magnetic resonance (NMR) studies in determining the residues located at the active site; thus, one needs to consider all these techniques when elucidating protein structure and function. For example, chemical modification of leukotriene A4 hydrolase, 3-hydroxyisobutyrate dehydrogenase, and lactate dehydrogenase (1-3) have contributed significantly to the understanding of active-site mechanisms in these proteins and in elucidating the mechanisms of DNA binding in the Fd and Pf 1 gene 5 proteins (4–5).