Suzuki M, Kametani S, Uchida K, Akanuma H
Department of Functional Material Science, Faculty of Engineering, Saitama University, Japan.
Eur J Biochem. 1996 Aug 15;240(1):23-9. doi: 10.1111/j.1432-1033.1996.0023h.x.
The pyranoid polyol 1,5-anhydroglucitol (1,5AnGlc-ol) occurs in a wide variety of organisms. In humans, it is present as one of the major monosaccharide components in body fluids and serves as an indicator for glycemic control in diabetic care. However, its metabolic origin and fate have been poorly understood. Here we demonstrate that 1,5AnGlc-ol is produced from glucose in erythroleukemia cells, K-562. We show the occurrence of 1,5-anhydrofructose (1,5AnFru), a derivative of 1,5AnGlc-ol oxidized at the C2 position, in K-562 cells. In addition, several pieces of evidence indicated that 1,5AnFru, rather than glucose, was the immediate precursor in 1,5AnGlc-ol production in erythroleukemia cells: exogenous 1,5AnFru was readily taken up into the cells and reduced to 1,5AnGlc-ol, but the reverse reaction, oxidation of 1,5AnGlc-ol to 1,5AnFru, was scarcely observed. The apparent K(m) of the overall cellular reduction for 1,5AnFru was estimated as 70 mg/l. This reduction was markedly inhibited by glucose in the culture medium but not by 1,5AnGlc-ol or glucitol. Since 1,5AnFru arises from alpha-1,4-glucans through lyase reactions in fungi and algae, we suggest the possibilities that glycogen in the precursor of 1,5AnFru and, therefore, 1,5AnGlc-ol originates from glycogen in mammals.
吡喃型多元醇1,5-脱水葡萄糖醇（1,5AnGlc-ol）存在于多种生物体中。在人类中，它作为体液中的主要单糖成分之一存在，并作为糖尿病护理中血糖控制的指标。然而，其代谢起源和去向一直未得到充分了解。在此，我们证明1,5AnGlc-ol是由红白血病细胞K-562中的葡萄糖产生的。我们展示了1,5-脱水果糖（1,5AnFru）的存在，它是1,5AnGlc-ol在C2位氧化的衍生物，存在于K-562细胞中。此外，多项证据表明，在红白血病细胞中，1,5AnFru而非葡萄糖是1,5AnGlc-ol产生的直接前体：外源性1,5AnFru很容易被细胞摄取并还原为1,5AnGlc-ol，但几乎未观察到1,5AnGlc-ol氧化为1,5AnFru的逆反应。细胞对1,5AnFru整体还原的表观K(m)估计为70 mg/l。这种还原受到培养基中葡萄糖的显著抑制，但不受1,5AnGlc-ol或葡糖醇的抑制。由于1,5AnFru通过真菌和藻类中的裂解酶反应由α-1,4-葡聚糖产生，我们推测1,5AnFru的前体糖原以及因此1,5AnGlc-ol的糖原起源于哺乳动物中的糖原的可能性。
