Jun Kisugi

A NOVEL ANTIMICROBIAL PEPTIDE FROM THE SEA HARE DOLABELLA AURICULARIA

The sea hare Dolabella auricularia is a marine shell-less gastropod. Four cytotoxic glycoproteins named dolabellanin A, C, E and P were found in the animal previously. An antimicrobial factor was newly isolated from the sea hares body-wall including skin and mucus. This factor is a novel peptide which consists of 33 amino acid residues, and is called dolabellanin B2. Dolabellanin B2 was cytotoxically effective against some pathogenic microorganisms at a concentration of 2.5-100 microg/ml.

Antifungal activity of aplysianin E, A cytotoxic protein of sea hare (Aplysia kurodai) eggs

We observed for the first time that antifungal activity was exhibited by Aplysianin E (AKE), an antineoplastic and antibacterial glycoprotein purified from the eggs of Aplysia kurodai. AKE completely suppressed growth of the yeast form fungi, Saccharomyces cerevisiae A 5 8 1 A, Schizosaccharomyces pombe JY 1 and Candida albicans ATCC 36232 at a concentration of over 16 micrograms/mL. The colony-forming abilities of the fungi were also significantly decreased after contact with AKE. These results indicate that AKE has an antifungal property and that its mode of action is fungicidal.

l-Amino acid oxidase activity of an antineoplastic factor of a marine mollusk and its relationship to cytotoxicity

Dolabellanin A (DAA), an antineoplastic protein of an ocean mollusk, was shown to have L-amino acid oxidase (LAAO, EC 1.4.3.2) activity. With the addition of DAA, a cytotoxic concentration of hydrogen peroxide was detected in the culture medium of EL-4 murine lymphoma cells. The cytotoxicity of DAA was suppressed by antioxidants, especially by catalase. The hydrogen peroxide produced by the LAAO activity was recognized to be involved in the cytotoxicity, and the cell death seemed to be due to the direct toxicity of this substance. However, the cytotoxicity of a higher concentration of DAA was only partially suppressed even when an excess amount of catalase was used. A portion of the cells that died showed features of apoptosis such as increased caspase 3 activity and DNA fragmentation. This indicated that apoptosis was induced by DAA activity but independently of the direct toxicity of hydrogen peroxide.

Purification of a cytolytic factor from purple fluid of a sea hare

A cytolytic factor inducing tumor lysis was purified approx. 1000‐fold from purple fluid of the sea hare Aplysia kurodai. The purified factor appeared homogeneous on polyacrylamide gel electrophoresis and consisted of a single polypeptide chain of 60 kDa. The cytolytic factor was half‐maximally active at 3–25 ng protein/ml and lysed all tumor cells tested, but not normal cells.

Purification of dolabellanin-C an antineoplastic glycoprotein in the body fluid of a sea hare, Dolabella auricularia

An antineoplastic factor, dolabellanin C, inducing tumor lysis was purified to apparent homogeneity from the body fluid of the sea hare Dollabella auricularia. Purified dolabellanin C is a glyco-protein of 215 K daltons containing 3 subunits of 70 K daltons. The amino acid sequence of the amino terminal region was also determined. This factor was active even at 0.38 ng protein/ml, but did not lyse normal white or red blood cells.

Purification of antineoplastic factor from eggs of a sea hare

An antineoplastic factor inducing tumor lysis was purified to apparent homogeneity from the supernatant of a homogenate of eggs of the sea hare Aplysia kwodai. On gel filtration, the purified substance gave a single band of material of 250 kDa containing 3 different subunits and this band coincided with cytolytic activity. The purified factor was half‐maximally active at 10–60 ng protein/ml and lysed all tumor cells tested, but not normal cells. Antineoplastic factor Tumor lysis Sea hare Aplysia Cytolysis