Ozaki I, Mitsui Y, Sugiya H, Furuyama S
Department of Physiology, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
Comp Biochem Physiol B Biochem Mol Biol. 2000 Jan;125(1):97-102. doi: 10.1016/s0305-0491(99)00156-x.
Fructose-1,6-bisphosphatase is one of the regulatory enzymes of gluconeogenesis in kidney cortex. The effect of ribose 1,5-bisphosphate on fructose-1,6-bisphosphatase purified from rat kidney cortex was studied. Rat kidney cortex, fructose-1,6-bisphosphatase exhibited hyperbolic kinetics with regard to its substrate, but the activity was inhibited by ribose 1,5-bisphosphate at nanomolar concentrations. The inhibitory effect of ribose 1,5-bisphosphate on the fructose-1,6-bisphosphatase was enhanced in the presence of AMP, one of the inhibitors of fructose-1,6-bisphosphatase. Fructose-2,6-bisphosphate, which is an inhibitor of fructose-1,6-bisphosphatase, inhibited rat kidney cortex fructose-1,6-bisphosphatase activities at a low concentration of fructose-1,6-bisphosphate but a high concentration of fructose-1,6-bisphosphate relieved fructose-1,6-bisphosphatase from fructose-2,6-bisphosphate-dependent inhibition. On the contrary, fructose-1,6-bisphosphate was not effective for the recovery of fructose-1,6-bisphosphatase from ribose 1,5-bisphosphate-dependent inhibition. These results suggest that ribose 1,5-bisphosphate is a potent inhibitor and is involved in the regulation of fructose-1,6-bisphosphatase in rat kidney cortex.
果糖-1,6-二磷酸酶是肾皮质中糖异生的调节酶之一。研究了1,5-二磷酸核糖对从大鼠肾皮质纯化的果糖-1,6-二磷酸酶的影响。在大鼠肾皮质中，果糖-1,6-二磷酸酶对其底物呈现双曲线动力学，但在纳摩尔浓度下其活性受到1,5-二磷酸核糖的抑制。在果糖-1,6-二磷酸酶抑制剂之一AMP存在的情况下，1,5-二磷酸核糖对果糖-1,6-二磷酸酶的抑制作用增强。果糖-2,6-二磷酸是果糖-1,6-二磷酸酶的抑制剂，在低浓度果糖-1,6-二磷酸时抑制大鼠肾皮质果糖-1,6-二磷酸酶的活性，但高浓度果糖-1,6-二磷酸可使果糖-1,6-二磷酸酶从果糖-2,6-二磷酸依赖性抑制中恢复。相反，果糖-1,6-二磷酸对果糖-1,6-二磷酸酶从1,5-二磷酸核糖依赖性抑制中恢复无效。这些结果表明，1,5-二磷酸核糖是一种有效的抑制剂，并参与大鼠肾皮质中果糖-1,6-二磷酸酶的调节。
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