Many chemical transformations such as hydrolysis, oxidations, and reductions are required for a wide range of industrial and biotechnological applications. In nature, these reactions are catalyzed by specialized enzymes. However, due to certain shortcomings such as low stability, substrate specificity, and high cost, most enzymes are not suitable for these applications. Therefore, several bioinspired organometallic complexes “artificial metalloenzymes” have been synthesized in the last few decades. In these complexes, metal ions, often nonbiological, are ligated to organic molecules instead of amino acid residues of enzymes. Additionally, they lack productive effects of electronic and non-covalent interactions of the protein surroundings. As a result, these complexes are significantly slower than the enzymes and with low turnovers. On the other hand, peptidic analogues such as β-sheet-rich amyloids, helical conformations, and hydrogels formed from amino acid residues provide enzyme-like first coordination shell and a productive combination of hydrophobic, hydrogen bonding, and metal binding effects. Consequently, in some cases, catalytic efficiencies of these analogues approach that of natural enzymes. Additionally, their activities can be improved further with the inclusion of catalytic and second coordination shell residues. In this chapter, structures, assemblies, and reactivities of multiple peptidic catalysts, both natural and de novo designed, are discussed in a systematic manner. Additionally, insights from our multiscale computational approaches on some of these systems are discussed.