Voll R J, Ramaprasad S, Vargas D, Younathan E S, Laban S, Koerner T A
Department of Biochemistry, Louisiana State University, Baton Rouge 70803.
Carbohydr Res. 1990 Aug 15;203(2):173-82. doi: 10.1016/0008-6215(90)80015-u.
Two-dimensional nuclear magnetic resonance studies have been carried out to assign unequivocally all the proton, carbon, and phosphorus resonances of D-fructofuranose 2,6-bisphosphate (1) and to verify its structure using a 400-MHz spectrometer. Several unexpected chemical-shift values and coupling constants were obtained. Molecular mechanics calculations (Sybyl) carried out to minimize the conformational energy of 1 yield phi C-1,P-2 = + 84, phi C-3,P-2 = - 155, and phi C-5,P-6 = + 175. Thus the unusual near-gauche orientations of C-1 and C-3 to P-2 in 1 can explain their small vicinal coupling constants (3JC-1,P-2 = 1.2, and 3JC-3,P-2 = 3.8 Hz), in contrast to the expected larger value seen for 3JC-5,P-6 namely, 6.9 Hz. Treatment of a sample of this compound with sodium borohydride did not affect its nuclear magnetic resonance spectrum, substantiating that O-2 is phosphorylated. Oxidation with sodium periodate yielded an intermediate which decomposed by a beta-elimination mechanism involving the 6-phosphate group. These data establish unequivocally the 1H, 13C, and 31P assignments and explain the observed anomalous shifts. Moreover they indicate that the activator of fructose 6-phosphate 1-kinase is the beta anomer of the 4T3 conformer of D-fructose 2,6-bisphosphate.
已进行二维核磁共振研究，以明确指定二磷酸 D - 果糖呋喃糖 2,6 - 双磷酸酯（1）的所有质子、碳和磷共振，并使用 400 - MHz 光谱仪验证其结构。获得了几个意外的化学位移值和耦合常数。进行分子力学计算（Sybyl）以最小化 1 的构象能量，得到 φ C - 1,P - 2 = + 84，φ C - 3,P - 2 = - 155，以及 φ C - 5,P - 6 = + 175。因此，1 中 C - 1 和 C - 3 相对于 P - 2 的不寻常近邻位取向可以解释它们较小的邻位耦合常数（3JC - 1,P - 2 = 1.2，以及 3JC - 3,P - 2 = 3.8 Hz），这与 3JC - 5,P - 6 预期的较大值（即 6.9 Hz）形成对比。用硼氢化钠处理该化合物样品不会影响其核磁共振光谱，证实 O - 2 被磷酸化。用高碘酸钠氧化产生一种中间体，该中间体通过涉及 6 - 磷酸基团的β - 消除机制分解。这些数据明确确定了 1H、13C 和 31P 的归属，并解释了观察到的异常位移。此外，它们表明果糖 6 - 磷酸 1 - 激酶的激活剂是 D - 果糖 2,6 - 双磷酸酯的 4T3 构象体的β - 异头物。
