The larger antimicrobial proteins, containing more than 100 amino acids, are often lytic enzymes. The smaller antimicrobial peptides act largely by disrupting the structure or function of microbial cell membranes. They have a net positive charge. The positive charge makes antimicrobial peptides selective, so they only adhere to negatively-charged bacterial cell membranes instead of host cell membranes.The most important antimicrobial proteins are Interferon and Complement proteins