**4. Anti‐bacterial protein from mucus of** *A. fulica*

Achacin is an antibacterial glycoprotein obtained from the mucus present on the body surface of *A. fulica*. Achacin is known not only to inhibit growth of both Gram‐positive and Gram‐ negative bacteria [26], but also appeared to attack the bacterial plasma membranes [27]. It is hypothesized that achacin is an active molecule although its role in controlling innate immu‐ nity warrants further research. However, the sequence of achacin has reported [28] its abil‐ ity to catalyze oxidative deamination producing ketoacids, hydrogen peroxide (H2 O2 ) and ammonia (NH3 ). The antibacterial activity of achacin was found to be dependent on H2 O2 production which is produced by the oxidative deamination reaction. Interestingly, LAOs in vertebrates also have antibacterial activity [29] which effects are most likely due to H<sup>2</sup> O2 formation. However, the concentration of achacin‐generated H2 O2 in the culture medium was not sufficient to inhibit bacterial growth [28]. Bacteria in their growth phase appeared to play an important role in the antibacterial activity of achacin. These data illustrate that when snails are infected by pathogens, achacin should bind to the plasma membranes of those that are proliferating. Achacin may attack pathogens during other growth phases too by increasing the local concentration of H2 O2 so as not to harm neighboring host cells. Thus, LAOs, which are widely distributed in living organisms, appeared to be of import in both vertebrate and invertebrate host defenses.
