Studies on Distribution of Marine Macro-algae in Europe Which Produce Novel Useful Enzymes and Their Structure-Function

海藻作为一种尚未开发的遗传资源，由于技术上的困难，其生物化学方面的研究很少。本研究的目的是从日本和欧洲收集的海洋大型藻类中发现新的酶。此外，我们的目的是阐明一个独特的钒依赖性卤代过氧化物酶（VHPO）的结构和功能，从海洋Cortina sp.在这项研究期间，我们收集了鸟取，埃克塞特，英国，和阿姆斯特丹，荷兰，然后确定各种酶活性的藻类无细胞提取物。我们发现了一个磷酸酶活性很高的细菌。该酶的最适pH值为8左右，最适温度为60-70℃，在60℃保温30 min后酶活力稳定性为60%，在pH值为3.5-9.0时酶活力稳定性为80%。此外，该酶对果糖1，6-二磷酸（53%），葡萄糖6-磷酸（19%），甘油醛3-磷酸（16%），以及对硝基苯磷酸（100%）的底物特异性。结果表明，holo-VHPO对四氢呋喃、乙腈、乙醇和丙酮都有耐受性，而apo-VHPO只对丙酮有耐受性。钙原子和钒酸根，酶的辅基，被认为是酶的稳定性的重要组成部分。

Little has been done about biochemical studies on marine algae as an undeveloped genetic resource mainly because of technical difficulty. The purpose of this study is to find novel enzymes from marine macro-algae collected in Japan and Europe. Moreover we aimed to elucidate the structure and function of a unique vanadium-dependent haloperoxidase (VHPO) from a marine alga Corallina sp.During the period of this study, we collected marine algae around Tottori, Exeter, U.K., and Amsterdam, the Netherlands, and then determined various enzyme activities of cell-free extracts of the algae. We found an alga with a high phosphatase activity. The enzyme activity showed an optimal pH of about 8, optimal temperature of 60-70℃, and the 60% and 80% stabilities after the incubation at 60℃ for 30 min and at pH 3.5-9.0, respectively. Furthermore, the enzyme showed the substrate specificity toward fructose 1,6-bisphosphate (53%), glucose 6-phosphate (19%), and glyceraldehyde 3-phosphate (16%) as well as p-nitrophenylphosphate (100%).We examined the factors for thermostability and organic solvent tolerance of VHPO of C.pilulifera. As a result, holo-VHPO showed tolerance against tetrahydrofuran and acetonitrile as well as ethanol and acetone, whereas apo-VHPO showed tolerance only against acetone.From the X-ray analyses of VHPO, we found the calcium atoms in the VHPO molecule. The Ca atom and vanadate, the prosthetic group of the enzyme, were found to play an important part of the enzyme stabilities.