Carrageenase　is　useful　for　preparation　of　carrageenan　oligosaccharides,　which　have　significant　bioactivity.　We　expressed　a　κ‑carrageenase　gene　from　Zobellia　sp.　ZL-4　in　full-length　(κ-ZL-4)　or　after　truncation　of　the　carbohydrate　binding　module　and　the　Type-IX　secretion　module　(κ-ZL-4-GH16).　κ-ZL-4-GH16　showed　a　specific　activity　(134.22　U/mg)　1.93　times　higher　than　that　of　κ-ZL-4,　and　its　thermal　and　pH　stability　also　increased.　The　best　activity　of　κ-ZL-4-GH16　was　presented　at　pH　3.0–6.0,　which　was　lower　than　the　optimal　pH　of　reported　κ-carrageenases.　The　enzyme-substrate　affinity　of　κ-ZL-4-GH16　was　higher　than　that　of　κ-ZL-4,　demonstrated　by　its　lower　Michaelis-Menten　constant　(0.704　mg/mL　at　pH　6.0).　Importantly,　κ-ZL-4-GH16　released　10-fold　more　κ-carrageenan　disaccharides　than　κ-ZL-4.　The　κ-carrageenan　tetrose　and　hexose　produced　by　the　two　enzymes　were　purified　and　structurally　identified.　Molecular　docking　with　κ-carrageenan　hexose　suggested　that　the　efficiency　improvement　after　truncation　might　be　attributed　to　the　conformation　differences　of　the　two　enzymes.　©　2019