Tolleshaug H, Berg T, Holte K
Eur J Cell Biol. 1980 Dec;23(1):104-9.
The rate constants for internalization of surface-bound asialo-orosomucoid by hepatocytes were 0.040 min-1 at 20 degrees C, 0.18 min-1 at 30 degrees C and 0.28 min-1 at 40 degrees C. At 40 degrees C, internalization accounted for most of the increase in cell-associated radioactivity. The activation energy over the temperature range 20 to 40 degrees C was 68 +/- 7 (S.D.) kJ/mol. At 10 degrees C, most of the cell-associated asialo-orosomucoid was bound to the cell surface in a reaction which followed ordinary chemical kinetics. Pre-incubation of hepatocytes with a large concentration of unlabelled asialo-orosomucoid did not influence the uptake of subsequently added 125I-asialofetuin; neither was degradation of 125I-asialo-fetuin affected in this experiment. The fractional rate of degradation (the fraction of cell-associated asialo-fetuin which was degraded per unit time) was constant over a twelve-fold range of intracellular asialo-fetuin concentrations. Increasing the temperature from 20 to 30 degrees C produced approximately a ten-fold increase in the rate of degradation of either asialo-fetuin or asialo-orosomucoid. The average activation energies of degradation over the range 20 to 40 degrees C were 125 kJ/mol for asialo-fetuin and 149 kJ/mol for asialo-orosomucoid; however, the Arrhenius plots were not straight lines over this temperature range.
肝细胞内化表面结合的去唾液酸血清类黏蛋白的速率常数在20℃时为0.040分钟⁻¹，30℃时为0.18分钟⁻¹，40℃时为0.28分钟⁻¹。在40℃时，内化作用是细胞相关放射性增加的主要原因。20至40℃温度范围内的活化能为68±7（标准差）kJ/mol。在10℃时，大部分细胞相关的去唾液酸血清类黏蛋白以遵循普通化学动力学的反应结合在细胞表面。用高浓度未标记的去唾液酸血清类黏蛋白对肝细胞进行预孵育，不影响随后加入的¹²⁵I-去唾液酸胎球蛋白的摄取；在该实验中¹²⁵I-去唾液酸胎球蛋白的降解也未受影响。在细胞内去唾液酸胎球蛋白浓度有12倍的范围内，降解的分数速率（单位时间内细胞相关去唾液酸胎球蛋白被降解的分数）是恒定的。将温度从20℃升高到30℃，去唾液酸胎球蛋白或去唾液酸血清类黏蛋白的降解速率大约增加10倍。20至40℃温度范围内去唾液酸胎球蛋白降解的平均活化能为125 kJ/mol，去唾液酸血清类黏蛋白为149 kJ/mol；然而，在这个温度范围内阿伦尼乌斯图不是直线。
