Blanchard J S, Brewer C F, Englard S, Avigad G
Biochemistry. 1982 Jan 5;21(1):75-81. doi: 10.1021/bi00530a014.
5-Keto-D-fructose (5KF) is isolated from cultures of Gluconobacter cerinus growing on D-fructose as the sole carbon source. 5KF is a substrate for hexokinase, fructokinase, and several polyol dehydrogenases. 1H and 13C nuclear magnetic resonance studies show that 5KF exists in different forms in anhydrous dimethyl-d6 sulfoxide and D2O. In dimethyl-d6 sulfoxide, 5KF exists as a spirane dimer with linked furanose and pyranose rings, similar to the structure reported for crystalline 5KF [Hassen, L., Hordvik, A., & Hove, R. (1976) J. Chem. Soc., Chem. Commun., 572-. In D2O, 5KF exists predominantly (greater than 95%) in a beta-pyranose form with the 5-keto group hydrated to form a gem-diol. 13C--1H coupling patterns, 13C relaxation measurements, and 13C deuterium-induced differential isotope shifts confirm this structure of 5KF. The phosphorylation of 5KF by fructokinase can be accounted for by an approximately 2% proportion of the beta-furanose form in solution at 25 degrees C. Both the beta-pyranose and beta-furanose forms of 5KF are proposed to be substrates for yeast hexokinase.
5-酮-D-果糖（5KF）是从以D-果糖作为唯一碳源生长的玫瑰色葡萄糖杆菌培养物中分离得到的。5KF是己糖激酶、果糖激酶和几种多元醇脱氢酶的底物。1H和13C核磁共振研究表明，5KF在无水氘代二甲亚砜和D2O中以不同形式存在。在氘代二甲亚砜中，5KF以一种具有连接的呋喃糖环和吡喃糖环的螺烷二聚体形式存在，类似于报道的结晶5KF的结构[哈森，L.，霍德维克，A.，&霍夫，R.（1976年）《化学学会杂志》，《化学通讯》，572 - 。在D2O中，5KF主要（大于95%）以β-吡喃糖形式存在，5-酮基水合形成偕二醇。13C - 1H耦合模式、13C弛豫测量和13C氘诱导的微分同位素位移证实了5KF的这种结构。在25℃下，溶液中约2%比例的β-呋喃糖形式可以解释果糖激酶对5KF的磷酸化作用。5KF的β-吡喃糖形式和β-呋喃糖形式都被认为是酵母己糖激酶的底物。
