There are several mechanisms for the immune system to destroy pathogens within the phagolysosome. One mechanism involves oxygen radicals. When cells are under stress they may produce more oxygen radicals, leading to oxidative stress which can damage cell structures. Another mechanism is through antimicrobial peptides. These are short protein fragments that kill bacteria. For example, defensins work by breaking down bacterial cell membranes. Another mechanism involves nitric oxide, which can combine with superoxide to create additional substances that can harm various biological molecules. Additionally, antimicrobial proteins specifically target and destroy bacteria. For example, proteases kill bacteria by breaking down essential proteins. Lastly, binding proteins play a crucial role in the immune system by binding to nutrients or ions that bacteria or viruses need to grow.