Whitehead L A, Stosz S K, Weiner R M
Department of Cell Biology and Molecular Genetics, University of Maryland, College Park 20742, USA.
Cytobios. 2001;106 Suppl 1:99-117.
A marine bacterium strain 2-40 (2-40) degraded numerous complex carbohydrates, such as agar, chitin and alginate. It may play an important role in altering carbon fluxes in marine environments. End-product analyses revealed that 2-40 synthesized an agarase system that consisted of at least three enzymes, beta-agarase I, beta-agarase II and alpha-agarase, which acted in concert to degrade polymeric agar to D-galactose and 3,6-anhydro-L-galactose. The agarase system was shown to be both cell envelope-associated and extracellular, with the relative concentrations depending on the growth phase. The principal depolymerase, a beta-agarase I, hydrolysed agar to both neoagarotetrose and neoagarobiose, as identified by thin layer chromatography. This agarase had a mass of 98 kD and a Pi of 4.3. The agarase system was repressed by D-glucose and D-galactose and induced by agar, agarose, neoagarobiose, neoagarotetrose and neoagarohexose.
一株海洋细菌菌株2-40（2-40）能降解多种复杂碳水化合物，如琼脂、几丁质和藻酸盐。它可能在改变海洋环境中的碳通量方面发挥重要作用。终产物分析表明，2-40合成了一种琼脂酶系统，该系统至少由三种酶组成，即β-琼脂酶I、β-琼脂酶II和α-琼脂酶，它们协同作用将聚合琼脂降解为D-半乳糖和3,6-脱水-L-半乳糖。琼脂酶系统显示既与细胞膜相关又存在于细胞外，其相对浓度取决于生长阶段。主要的解聚酶，即β-琼脂酶I，经薄层色谱鉴定，可将琼脂水解为新琼脂四糖和新琼脂二糖。这种琼脂酶的质量为98 kD，等电点为4.3。琼脂酶系统受到D-葡萄糖和D-半乳糖的抑制，而受到琼脂、琼脂糖、新琼脂二糖、新琼脂四糖和新琼脂己糖的诱导。
