Biochimica et Biophysica Acta (BBA) - General Subjects ( IF 2.8 ) Pub Date : 2020-09-19 , DOI: 10.1016/j.bbagen.2020.129740 Yirong Xu 1 , Ping Chi 1 , Jiyang Lv 1 , Muhammad Bilal 2 , Hairong Cheng 1
Background
In acetic acid bacteria such as Gluconobacter oxydans or Gluconobacter cerinus, pyrroloquinoline quinone (PQQ) in the periplasm serves as the redox cofactor for several membrane-bound dehydrogenases that oxidize polyhydric alcohols to rare sugars, which can be used as a healthy alternative for traditional sugars and sweeteners. These oxidation reactions obey the generally accepted Bertrand Hudson's rule, in which only the polyhydric alcohols that possess cis d-erythro hydroxyl groups can be oxidized to 2-ketoses using PQQ as a cofactor, while the polyhydric alcohols excluding cis d-erythro hydroxyl groups ruled out oxidation by PQQ-dependent membrane-bound dehydrogenases.
Methods
Membrane fractions of G. oxydans were prepared and used as a cell-free catalyst to oxidize galactitol, with or without PQQ as a cofactor.
Results
In this study, we reported an interesting oxidation reaction that the polyhydric alcohols galactitol (dulcitol), which do not possess cis d-erythro hydroxyl groups, can be oxidized by PQQ-dependent membrane-bound dehydrogenase(s) of acetic acid bacteria at the C-3 and C-5 hydroxyl groups to produce rare sugars l-xylo-3-hexulose and d-tagatose.
Conclusions
This reaction may represent an exception to Bertrand Hudson's rule.
General significance
Bertrand Hudson's rule is a well-known theory in polyhydric alcohols oxidation by PQQ-dependent membrane-bound dehydrogenase in acetic acid bacteria. In this study, galactitol oxidation by a PQQ-dependent membrane-bound dehydrogenase represents an exception to the Bertrand Hudson's rule. Further identification of the associated enzymes and deciphering the explicit enzymatic mechanism will prove this theory.
中文翻译:
L-木糖-3-己糖,一种新的稀有糖,由乙酸细菌作用于半乳糖醇而产生,是贝特朗·哈德森法则的一个例外。
背景
在醋酸细菌中,如氧化葡糖杆菌或蜡状葡糖杆菌,周质中的吡咯并喹啉醌(PQQ)充当几种膜结合脱氢酶的氧化还原辅因子,这些酶将多元醇氧化为稀有糖,可以用作传统糖的健康替代品和甜味剂。这些氧化反应服从普遍接受贝特朗Hudson的规则,其中仅具有多元醇的顺式d -赤羟基可以被氧化成使用PQQ作为辅因子2-酮糖,而多元醇不含顺d排除-赤羟基消除了PQQ依赖的膜结合脱氢酶的氧化作用。
方法
制备G.oxydans的膜级分,并在有或没有PQQ作为辅因子的情况下用作氧化半乳糖醇的无细胞催化剂。
结果
在这项研究中,我们报道了一个有趣的氧化反应,该多元醇半乳糖醇(卫矛醇),其不具有顺d -赤羟基,可以通过PQQ依赖性膜结合脱氢酶(S)乙酸菌中的氧化C-3和C-5羟基可产生稀有的糖1 -xylo-3-hexulose和d - tagatose。
结论
这种反应可能是贝特朗·哈德森规则的一个例外。
一般意义
Bertrand Hudson法则是在乙酸细菌中多元醇被PQQ依赖的膜结合脱氢酶氧化的著名理论。在这项研究中,PQQ依赖的膜结合脱氢酶对半乳糖醇的氧化代表了Bertrand Hudson法则的一个例外。进一步鉴定相关酶并破译明确的酶促机理将证明这一理论。