The extracellular agarase from a Cytophaga species was shown to have no action on neoagarobiose, neoagarotetraose or their analogues containing 6-O-methyl-d-galactose residues. 2. The action of the enzyme on neoagaro-octaose suggests that scission of the central beta-d-galactosidic linkage, to form two molecules of tetrasaccharide, is the preferred mode of action; however, both exterior d-galactosidic linkages in the octasaccharide and both in neoagarohexaose are hydrolysed at a somewhat lower rate. 3. Sulphated oligosaccharides produced by prolonged enzyme action on porphyran have a minimum degree of polymerization of about 8-10units. 4. For such sulphated oligosaccharides to be further hydrolysed by enzyme action, it is suggested that an unmodified neoagarotetraose residue must be present in the oligosaccharide. 6. A new method for determining the degree of polymerization of these large oligosaccharides is described.
