Background
Parasin I is an antimicrobial peptide fragment from the N-terminal region of histone H2A in catfish (P. asotus) that is involved in host defense.1 It is formed from histone H2A by cathepsin D in the skin mucosa of wounded P. asotus. Parasin I is active against various Gram-positive and Gram-negative bacteria, as well as fungi (MICs = 1-2, 1-4, and 1-2 μg/ml, respectively).2