Protein engineering is a research field and methodological approach concerned with the rational design, modification, and synthesis of proteins to imbue them with novel or enhanced biological, chemical, or physical functions. This discipline systematically investigates the intricate relationship between protein structure and function, utilizing techniques such as site-directed mutagenesis, directed evolution, and computational design to create molecules optimized for specific applications across medicine, biotechnology, and industry, thereby extending the functional repertoire of natural proteins.