Novel antitumor and antimicrobial glycoproteins were found in the sea hares. These glycoproteins were purified to apparent homogeneity from Aplysia kurodai, Aplysia juliana and Dolabella auricularia, and designated as aplysianins, julianins and dolabellanins, respectively. 2. The nine isolated glycoproteins lysed all the tumor cells tested but did not lyse normal white and red blood cells. 3. The glycoproteins completely inhibited the synthesis of DNA and RNA by tumor cells within 2 hr and caused tumor lysis within 15 hr. 4. Tumor lysis was inhibited by the presence of N-acetylneuraminic acid, suggesting that the recognition of the sugar moiety is a key step in the cytolysis by antitumor glycoproteins from sea hares. 5. These antitumor glycoproteins, except dolabellanin P, also showed antimicrobial activities. 6. The factors were active for Gram-positive and -negative bacteria and some fungi, and their action was not cytocidal but cytostatic. 7. They exerted the antibacterial action by inhibiting nucleic acid synthesis, as does a DNA-inhibiting chemotherapeutic drug. 8. The sequence of the N-terminal part of dolabellanin A was similar to other antibacterial peptides from arthropoda, amphibia and mammals, suggesting that dolabellanin-like antibacterial peptides are common throughout the animal kingdom.
