Naftalin R J, Rist R J
Biomedical Sciences Division, King's College London, UK.
Biochim Biophys Acta. 1994 Apr 20;1191(1):65-78. doi: 10.1016/0005-2736(94)90234-8.
(1). The kinetic parameters of zero-trans net uptake and infinite-trans uptake of 3-O-methyl-D-glucoside, 2-deoxy-D-glucose and D-mannose into rat red cells at 24 degrees C were measured after taking account of the linear diffusion components of flux. (2). Zero-trans exists of 3-O-methyl-D-glucoside and D-mannose from rat cells were also measured. (3). After correction for linear flux via non-specific routes, the Vmax of zero-trans uptake of 3-O-methyl-D-glucoside was significantly higher, (1.25 +/- 0.06 mumol (10 min)-1 (ml cell water)-1) than the corresponding parameters of mannose or 2-deoxy-D-glucose, (0.33 +/- 0.01 and 0.39 +/- 0.01 mumol(10 min)-1 (ml cell water)-1, respectively; P < 0.001). (4). After correction for linear flux via non-specific uptake routes, the Vmax of zero-trans exit of 3-O-methyl-D-glucoside is significantly higher (1.70 +/- 0.1 mumol (10 min)-1 (ml cell water)-1) than the corresponding value for mannose exit flux, (1.10 +/- 0.1 mumol (10 min)-1 (ml cell water)-1; P < 0.001). (5). The acceleration ratio, i.e., the ratio of infinite-trans influx Vmax/zero-trans influx Vmax of mannose by mannose (9.12 +/- 0.03) is significantly higher than that of 3-O-methyl-D-glucose by 3-O-methyl-D-glucose (2.77 +/- 0.14)(P < 0.001). (6). The one-site simple carrier model of glucose transport in which sugar exchange is viewed as a sequential process, predicts that the acceleration ratio of the more rapidly moving sugar 3-O-methyl-D-glucose by 3-O-methyl-D-glucose should be greater than that of the slower sugar, mannose by mannose. Hence, the observed findings are inconsistent with the one-site model, but confirm the earlier disputed studies of Miller, D.M. (1968; Biophys. J. 8, 1329-1338). (7). A two-site model, in which sugar exchange is considered as a simultaneous process, predicts that the acceleration ratio of mannose influx by mannose should be higher than for 3-O-methyl-D-glucose by 3-O-methyl-D-glucose. The data are, therefore, consistent with a two-site model.
(1). 在考虑通量的线性扩散成分后，于24℃测定了3 - O - 甲基 - D - 葡萄糖苷、2 - 脱氧 - D - 葡萄糖和D - 甘露糖进入大鼠红细胞的零转运净摄取和无限转运摄取的动力学参数。(2). 还测定了大鼠细胞中3 - O - 甲基 - D - 葡萄糖苷和D - 甘露糖的零转运存在情况。(3). 通过非特异性途径对线性通量进行校正后，3 - O - 甲基 - D - 葡萄糖苷零转运摄取的Vmax显著更高，为(1.25±0.06 μmol(10 min)-1(ml细胞水)-1)，高于甘露糖或2 - 脱氧 - D - 葡萄糖的相应参数，分别为(0.33±0.01和0.39±0.01 μmol(10 min)-1(ml细胞水)-1；P < 0.001)。(4). 通过非特异性摄取途径对线性通量进行校正后，3 - O - 甲基 - D - 葡萄糖苷零转运流出的Vmax显著更高(1.70±0.1 μmol(10 min)-1(ml细胞水)-1)，高于甘露糖流出通量的相应值(1.10±0.1 μmol(10 min)-1(ml细胞水)-1；P < 0.001)。(5). 加速比，即甘露糖通过甘露糖的无限转运流入Vmax/零转运流入Vmax的比值(9.12±0.03)显著高于3 - O - 甲基 - D - 葡萄糖通过3 - O - 甲基 - D - 葡萄糖的比值(2.77±0.14)(P < 0.001)。(6). 将糖交换视为连续过程的葡萄糖转运的单位点简单载体模型预测，移动速度更快的糖3 - O - 甲基 - D - 葡萄糖通过3 - O - 甲基 - D - 葡萄糖的加速比应大于移动较慢的糖甘露糖通过甘露糖的加速比。因此，观察到的结果与单位点模型不一致，但证实了Miller, D.M. (1968; Biophys. J. 8, 1329 - 1338)早期有争议的研究。(7). 将糖交换视为同时过程的双位点模型预测，甘露糖通过甘露糖的流入加速比应高于3 - O - 甲基 - D - 葡萄糖通过3 - O - 甲基 - D - 葡萄糖的加速比。因此，数据与双位点模型一致。
