L-Fucose metabolism in mammals. The conversion of L-fucose to two moles of L-lactate, of L-galactose to L-lactate and glycerate, and of D-arabinose to L-lactate and glycollate.
L-Fucose metabolism in mammals. The conversion of L-fucose to two moles of L-lactate, of L-galactose to L-lactate and glycerate, and of D-arabinose to L-lactate and glycollate.
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哺乳动物中的 L-岩藻糖代谢。
DOI：
10.1016/s0021-9258(18)50284-2
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
H. Schachter
中科院分区：
文献类型：
--
作者：
J. Chan;N. Nwokoro;H. Schachter
在猪肝中发现了一条新的~-岩藻糖氧化途径。途径如下：L-岩藻糖+L-岩藻酸内酯--$L-岩藻酸盐+2-酮基-3-脱氧-L，-岩藻酸盐+未知中间体，可能是2，4-二酮基-5-羟基己酸盐-+2 mol L-乳酸盐。先前的工作（Nwokoro，NA，and Schachter，H.（1975）J.Biol.Chem.250，6185 - 6196）提供了通向2，4-二酮基-5-羟基己酸阶段的途径的证据，并表明D-阿拉伯糖通过相同的途径被氧化。在本文中，它表明，r-. -半乳糖可被氧化成2-酮-3-脱氧+半乳糖酸。进一步表明，猪肝含有一种酶系统，该酶系统可以将1摩尔2-酮基-3-脱氧-L-将1摩尔2-酮基-3-脱氧-D-阿拉伯糖酸盐与0.9摩尔L-乳酸盐和0.9摩尔乙醇酸盐混合，将2-酮基-3-脱氧+半乳糖酸盐与L. -乳酸盐混合。乳酸和甘油酸。该反应完全依赖于NAD+的存在，表明反应中的第一种酶可能是2-酮基-3-脱氧-L-岩藻酸盐：NAD+氧化还原酶，其先前已从猪肝中纯化至均一。通过显示2-酮基-3-脱氧-L-[1 - 14C，6 - 3H]岩藻酸盐以相同的3H/14C比率转化为[1 - 14C，3H]乳酸盐，获得了该途径的有力证据。只有猪肝脏和肾脏中有明显水平的L-岩藻糖：NAD+氧化还原酶、L-岩藻酸水解酶和2-酮-3-脱氧-L-岩藻酸：NAD+氧化还原酶，它们是该途径中的主要酶;猪心，胃，肠，颌下腺，肺，和大脑缺乏或完全缺乏这三种酶。（6-脱氧-L-半乳糖）是微生物、植物和动物合成的许多糖蛋白和糖脂的成分（2 - 9）。放射性L-岩藻糖（10 - 19）和GDP-L-岩藻糖（20 - 23）已被用于各种系统中，以研究含岩藻糖大分子的生物合成。放射性L-岩藻糖被认为是此类研究的优秀前体，因为它不会转化为其他糖（16 - 19，24，25）。然而，肠胃外施用的游离L-岩藻糖可被微生物广泛氧化成二氧化碳。
A novel oxidative pathway for~-fucose has been found in pig liver. The pathway is as follows: L-fucose+ L-fuconolactone--$ L-fuconate+ 2-keto-3-deoxy-L,-fuconate+ unknown intermediate, probably 2, 4-diketo-5-hydroxyhexanoate-+ 2 mol of L-lactate. Previous work (Nwokoro, NA, and Schachter, H.(1975) J. Biol. Chem. 250, 6185-6196) has provided evidence for the pathway to the 2, 4-diketo-5-hydroxyhexanoate stage, and has shown that D-arabinose is oxidized by the same pathway. In the present paper, it is shown that r-.-galactose can be oxidized to 2-keto-3-deoxy+ galactonate. It is further shown that pig liver contains an enzyme system which can convert 1 mol of 2-keto-3-deoxy-L.-fuconate to 1.7 mol of L-lactate, 1 mol of 2-keto-3-deoxy-D-arabonate to 0.9 mol of L-lactate and 0.9 mol of glycollate, and 2-keto-3-deoxy+ galactonate to L.-lactate and glycerate. The reaction is absolutely dependent on the presence of NAD’indicating that the first enzyme in the reaction is probably 2-keto-3-deoxy-L-fuconate: NAD+ oxidoreductase which has previously been purified to homogeneity from pig liver. Definitive evidence for the pathway was obtained by showing the conversion of 2-keto-3-deoxy-L-[l-‘4C, 6-3H] fuconate to r $‘C, 3H] lactate with the same 3H/14C ratio. Only pig liver and kidney were found to have appreciable levels of L-fucose: NAD+ oxidoreductase, L-fuconate hydro-lyase, and 2-keto-3-deoxy-L-fuconate: NAD+ oxidoreductase, the major enzymes in the pathway; pig heart, stomach, intestine, submaxillary gland, lung, and brain were deficient in or lacked completely all three enzymes.L-Fucose (6deoxy-L-galactose) is a constituent of many glycoproteins and glycolipids synthesized by microorganisms, plants, and animals (2-9). Radioactive L-fucose (10-19) and GDP-L-fucose (20-23) have been used in a variety of systems to study the biosynthesis of fucose-containing macromolecules. Radioactive L-fucose is considered to be an excellent precursor for such studies because it is not converted to other sugars (16-19, 24, 25). Parenterally administered free L-fucose can, however, be extensively oxidized to carbon dioxide by the