Enzyme-mediated methodologies for protein modification and bioconjugate synthesis

Bioconjugates are valuable tools in many fields, including protein engineering and environmental and therapeutic research. Chemical methods are commonly used to synthesize protein-protein and protein-functional molecule bioconjugates because they permit easy tethering through covalent bonds. However, chemical methods often produce heterogeneous products and lead to degradation of protein activity due to random modifications. Recently, a number of techniques for modifying proteins or synthesizing bioconjugates have been reported, including more sophisticated chemical modification methods, utilization of noncovalent affinity, and protein splicing. Enzymatic methods in particular have attracted much attention due to the substrate specificity of enzymes, which enables site-specific tethering of proteins to other proteins or functional molecules. Here, we discuss newly developed methods for protein modification and bioconjugate synthesis that exploit the properties of acyltransferases, ligases, and other enzymes.