Marine living organisms and their main and secondary compounds and metabolites are among the richest in biological diversity. Many of their fundamental qualities and applications are still fully or partially unexplored. Given that enzymes are essential in the plethora of biological functions of these organisms, it is increasingly evident that enzyme inhibitors are also involved in the control of these functions, as well as in many diseases and attack-defense processes. Research on the natural inhibitors found in marine organisms is, therefore, of great interest at present in a myriad of research perspectives.The present Special Issue collected novel research on non-peptide or peptide/protein inhibitors, or derived forms, with a focus on isolation, structure-function characterization, methods of action, variety, evolution, screening, and genomics-proteomics. Particular emphasis is placed on enzyme inhibitors from marine invertebrates, microorganisms, and algae, still not well understood. Additionally, studies on the potential value of such molecules for biological, biotechnological, and pharmaceutical/biomedical uses, particularly as drugs or lead compounds, are taken into account.
