||Enzymes have been widely employed in industries and medicine and enzymes with better stability and function than natural enzymes have been always sought for industrial applications of enzymes. Enzyme discovery and engineering has been extensively performed to unveil important biological functions of enzymes in metabolic pathways or to use enzymes in industrial processes. In industries, enzyme and metabolic engineering approaches have been extensively explored to replace chemical routes based on petroleum. It is thus important to discover metabolic enzymes capable of catalyzing target reactions in metabolic pathways. In medicine, enzyme inhibition by high concentrations of substrates or cofactors has been investigated to understand a biologically relevant regulatory mechanism in enzymes from pathogenic bacteria. Here, we present enzyme discovery and engineering studies for better industrial applications of enzymes.