Cytotoxicity and Glycan-Binding Properties of an 18 kDa Lectin Isolated from the Marine Sponge <em>Halichondria </em><em>o</em><em>kadai</em>

Abstract

A divalent cation-independent lectin—HOL-18, with cytotoxic activity against leukemia cells, was purified from a demosponge, <em>Halichondria okadai</em>. HOL-18 is a 72 kDa tetrameric lectin that consists of four non-covalently bonded 18 kDa subunits. Hemagglutination activity of the lectin was strongly inhibited by chitotriose (GlcNAcβ1-4GlcNAcβ1-4GlcNAc), fetuin and mucins from porcine stomach and bovine submaxillary gland. Lectin activity was stable at pH 4–12 and temperatures lower than 60 °C. Frontal affinity chromatography with 16 types of pyridylaminated oligosaccharides indicated that the lectin had an affinity for <em>N</em>-linked complex-type and sphingolipid-type oligosaccharides with <em>N</em>-acetylated hexosamines and neuramic acid at the non-reducing termini. The lectin killed Jurkat leukemia T cells and K562 erythroleukemia cells in a dose- and carbohydrate-dependent manner.

Keywords

• cytotoxicity
• frontal affinity chromatography technology
• glycoprotein
• Japanese black sponge (&lt;em&gt;Halichondria okadai&lt;/em&gt;)
• lectin