Trihydroxyphenylalanine quinone (TPQ) from copper amine oxidases and lysyl tyrosylquinone (LTQ) from lysyl oxidase

Abstract

The chapter discusses the four quinone cofactors that use reactive carbonyls to catalyze amine or alcohol oxidation. These includes, trihydroxyphenylalanine quinone (TPQ) found in copper amine oxidases (CAOs) and lysine tyrosylquinone (LTQ) found in lysyl oxi- dase (LOX) are discussed in this chapter. Pyrroloquinoline quinone (PQQ) and tryptophan tryptophylquinone (TRQ) are found in enzymes that catalyze the oxidation of alcohols and amines, respectively. TPQ, LTQ and TTQ are the examples of an exciting area of enzymology in which new functionalities derived from the post-translational modification of amino acid side chains expand the chemical capabilities of an enzyme beyond the natural amino acids. This chapter focuses on the recent advances in understanding the mechanisms of catalysis and (TPQ) formation in copper amine oxidases (CAOs). The chapter also discusses the progress in understanding the biological roles of these enzymes. Although the mechanisms of catalysis and cofactor formation in lysyl oxidase (LOX) are less well developed, the available data for LOX are considered in the context of the CAOs. Finally, the sequences and possible biological roles of a recently reported family of LOX-like enzymes are described.