Overview of PepNzymes covering development, structure, functions, enzyme-like activities, and biomedical applications. (A) Timeline of critical events of peptides, enzyme-like peptides, nanozymes, PepNzymes, etc. (B) A possbile evolution from ions, nanoscale minerals/nanozymes, peptides, PepNzymes, to enzymes. (C) Types of PepNzymes. (D) Peptide functions in PepNzymes. (E) Enzyme-like activities of PepNzymes. (F) Biomedical applications.