Ulvan lyase is a useful tool which can degrade ulvan into oligosaccharides with a range of biological activities. In this study, the ulvan lyase ULA-3 from Alteromonas sp. 76–1, which was a 1467-bp encoded 489-amino acid residue protein, has been cloned, heterologously expressed and biochemically characterized. ULA-3 showed the maximum activity at 45 ˚C and pH 9.0. The K_m is 1.879 mg mL⁻¹ and V_max is 2.597 µmol min⁻¹ mL⁻¹. Its enzyme activity was outstanding at 11.754 U mg⁻¹. Moreover, its metal ion stability is exceptionally good and most metal ions at a concentration of 1 mM have no inhibitory effect on its activity. It can endolytically degrade ulvan into oligosaccharides with a degree of polymerization (Dp) of 2–4 and with unsaturated double bond through the β-elimination reaction, which mainly cleaves the glycosidic bond between rhamnose and uronic acids. All in all, our study has increased the ulvan lyase database and offers the opportunity to fully utilize ulvan, a green biomass resource from marine algae.

绿藻硫化多糖裂解酶是一种有用的工具，可以将绿藻硫化多糖降解为具有一系列生物活性的寡糖。在本研究中，来自交替单胞菌的绿藻硫化多糖裂解酶 ULA-3。76-1 是一个 1467 bp 编码的 489 个氨基酸残基的蛋白质，已被克隆、异源表达和生化表征。ULA-3 在 45 ℃ 和 pH 9.0 时表现出最大活性。K _m为1.879 mg mL ^-1且V _max为2.597 µmol min ^-1  mL ^-1。其酶活性非常出色，为 11.754 U mg ⁻¹。而且其金属离子稳定性特别好，大多数金属离子在1 mM浓度下对其活性无抑制作用。它可以通过β-消除反应，将绿藻硫化多糖内切降解为聚合度（Dp）为2-4、具有不饱和双键的寡糖，主要裂解鼠李糖和糖醛酸之间的糖苷键。总而言之，我们的研究增加了绿藻多糖裂解酶数据库，并为充分利用绿藻多糖（一种来自海藻的绿色生物质资源）提供了机会。