| Determination of Recombinant Mannitol-1-phosphate Dehydrogenase Activity from Ectocarpus sp.
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Author:
Date:
2016-11-05
[Abstract] Brown algae belong to a phylogenetic lineage distantly related to green plants and animals, and are found predominantly, but not exclusively, in the intertidal zone, a harsh and frequently changing environment. Because of their unique evolutionary history and of their habitat, brown algae feature several peculiarities in their metabolism. One of these is the mannitol cycle, which plays a central role in their physiology, as mannitol acts as carbon storage, osmoprotectant, and antioxidant. This polyol is derived directly from the photoassimilate fructose-6-phosphate via the action of a ...
[摘要] 褐藻属于与绿色植物和动物遥远相关的系统发生谱系，并且主要发现于但不限于潮间带，一种苛刻且频繁变化的环境。由于它们独特的进化史和它们的栖息地，褐藻具有其代谢中的一些特性。其中之一是甘露醇循环，其在其生理学中发挥中心作用，因为甘露糖醇充当碳储存，渗透保护剂和抗氧化剂。该多元醇通过甘露醇-1-磷酸酯脱氢酶（M1PDH，EC 1.1.1.17）和甘露醇-1-磷酸酶（M1Pase，EC 3.1.3.22）的作用直接从光生酸酯果糖-6-磷酸衍生。该协议描述了在Ectocarpus中鉴定的三种M1PDH之一的重组催化结构域的生物化学表征。该重组催化结构域（下文称为M1PDHcat）使用NAD（H）作为辅因子催化果糖-6-磷酸（F6P）向甘露醇-1-磷酸（M1P）的可逆转化。 M1PDHcat活性在两个方向上测定，即，F6P还原和M1P氧化（图1）。
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图1.甘露醇-1-磷酸脱氢酶的可逆反应
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| Measurement of Glucose-6-phosphate Dehydrogenase Activity in Bacterial Cell-free Extracts
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Author:
Date:
2016-10-05
[Abstract] Glucose-6-phosphate dehydrogenase (G6PDH) (EC 1.1.1.49) is the first enzyme of the oxidative pentose phosphate cycle and catalyses the conversion of glucose-6-phosphate (G6P) to 6-phosphoglucono-δ-lactone and transfers one electron to NADP+ producing one NADPH. Conversion of G6P to 6-phosphoglucono-δ-lactone is proportional to the production of NADPH. The increase in NADPH concentration results in an increase in absorbance at 340 nm. To assay G6PDH activity, therefore, production of NADPH is determined by measuring increase in absorbance at 340 nm spectrophotometrically. This ...
[摘要] 葡萄糖-6-磷酸脱氢酶（G6PDH）（EC 1.1.1.49）是氧化戊糖磷酸循环的第一个酶，并催化葡萄糖-6-磷酸（G6P）转化为6-磷酸葡萄糖酸-δ-内酯并将一个电子 到NADP +产生一种NADPH。 G6P向6-磷酸葡萄糖酸-δ-内酯的转化与NADPH的产生成比例。 NADPH浓度的增加导致340nm处吸光度的增加。 因此，为了测定G6PDH活性，通过分光光度法测量340nm处吸光度的增加来确定NADPH的产生。 然后将该增加速率转化为G6PDH的活性和比活性的单位。 在该程序中，给出了强调蓝细菌集胞藻的细菌G6PDH测定的一般方法。 PCC6803（Schaeffer和Stanier，1978; Karakaya等人，2008，2012）和异养细菌大肠杆菌（Hylemon和Phibbs，1972; Barnel等人 ，1990）。
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| Determination of Mannitol-2-dehydrogenase Activity
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Author:
Date:
2015-11-05
[Abstract] Mannitol is a polyol that occurs in a wide range of living organisms, where it fulfills different physiological roles. Several pathways have been described for the metabolism of mannitol by bacteria, including the phosphoenolpyruvate-dependent phosphotransferase system (PST) and a M2DH-based catabolic pathway. The latter involves two enzymes, a mannitol-2-dehydrogenase (EC 1.1.1.67) and a fructokinase (EC 2.7.1.4), and has been identified in different bacteria, e.g., the marine Bacteroidetes Zobellia galactanivorans (Zg) which had recently gained interest to study ...
[摘要] 甘露醇是在多种活生物体中发生的多元醇，其中它实现不同的生理作用。已经描述了用于由细菌代谢甘露醇的几种途径，包括磷酸烯醇丙酮酸依赖性磷酸转移酶系统（PST）和基于M2DH的分解代谢途径。后者涉及两种酶，甘露醇-2-脱氢酶（EC 1.1.1.67）和果糖激酶（EC 2.7.1.4），并且已经在不同的细菌中鉴定，例如， 海洋拟杆菌（Zobellia galactanivorans）（ Zg ），最近对研究大分子多糖降解有兴趣。该方案描述了半乳聚糖微生物的重组甘露醇-2-脱氢酶（M2DH）的生物化学表征。使用NAD +辅助作为辅因子，M2DH酶催化甘露醇向果糖的可逆转化。 在两个方向上测定M2DH活性，即果糖还原和甘露醇氧化。
可逆反应：
D-甘露醇+ NAD + ↔D-果糖+ NADH + H +
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