Catalysis of the cleavage of a carbon-oxygen bond in ulvan, a carbohydrate composed of a repeating structure of n. Continued digest of ulvan with an enzyme that can catalyze this reaction results in ulvanobiouronic acid A 3-sulfate n with 4-deoxy-L-threo-hex-4-enopyranosiduronic acid at the non-reducing end.
ulvan lyase activity