Antimicrobial peptide that has a large activity spectrum with activity against Gram-positive, Gram-negative bacteria, as well as against fungi (PubMed:17658600, PubMed:23326415). Shows activity at micromolar concentrations (PubMed:17658600, PubMed:23326415). Displays minimal inhibitory concentration (MIC) values lower than minimal bactericidal concentrations (MBC) (PubMed:17658600). Synthetic peptides with similar activities than the full length peptide (composed of the first 23 or 25 amino acids (Arasin 1(26-48) or Arasin 1(26-50))) may have a dual mode of action depending on the peptide concentrations (PubMed:23326415, PubMed:26860543). At MIC concentrations, the peptide penetrates into the cytoplasm of target cells (tested on the Gram-negative E.Coli) (PubMed:26860543). The two inner membrane proteins YgdD and SbmA may be required for this uptake (PubMed:26860543). At concentrations higher than MIC, arasin may act by disrupting membranes (PubMed:23326415). Full-length and N-terminal peptides do not show hemolytic activity (PubMed:23326415). Interacts with chitin through the N-terminal region (26-48) (PubMed:23326415). This interaction may be important, since chitin is a component of the fungal cell wall, as well as of the crab exoskeleton (permitting a possible action of arasin in wound healing in case of lesions) (PubMed:23326415). Mainly expressed in hemocytes. No or very low expression in heart, gills, inestines, and epidermis. Disulfide bonds are important for activity especially against Gram-negative bacteria, since the linearization of the peptide causes a strong decrease of activity on these bacteria. Monoisotopic mass.