Protein inhibitors are molecules that bind to proteins and inhibit or block their activity. These inhibitors can be used in research to study the function of specific proteins, as well as in drug development to target proteins involved in diseases such as cancer, Alzheimer's, and HIV. Protein inhibitors can be small molecules, peptides, or antibodies, and they work by blocking key interactions or binding sites on the target protein. By understanding the mechanisms of protein inhibition, researchers can design more effective drugs with fewer side effects.