The action of a bacterial agarase on agarose, porphyran and alkali-treated porphyran.

1. A purified extracellular agarase from a Cytophaga species was used to hydrolyse agarose, porphyran and alkali-treated porphyran. 2. The hydrolysate from agarose was separated by gel filtration into the series of neoagarosaccharides, the predominant member of which was the tetrasaccharide. 3. Enzyme action on alkali-treated porphyran gave neoagarosaccharides and other oligosaccharides containing 6-O-methyl-d-galactose units. From the composition of these oligosaccharides it is deduced that action of the enzyme on a d-galactosidic linkage is four to five times faster than on the 6-O-methyl-d-galactosidic linkage. 4. Enzyme action on native porphyran gives a similar series of oligosaccharides but in smaller yield, much of the polysaccharide being either not degraded or only degraded to a series of large, highly sulphated oligosaccharides. 5. For porphyran, it is concluded that 6-O-methyl ether groups are distributed randomly on half the d-galactose units, but that the 6-sulphate groups on l-galactose units tend to occur in blocks.