Bar-On Z, Degani H
Biochim Biophys Acta. 1985 Mar 14;813(2):207-12. doi: 10.1016/0005-2736(85)90235-4.
The exchange rate and enthalpy and entropy of activation of the diffusion of the first five n-alkylamines across egg phosphatidylcholine vesicles has been measured by 1H-NMR spectroscopy employing the 1:2 Gd3+-EDTA complex as a relaxation reagent. The permeability determined from the exchange rate of the ethyl through the pentyl derivatives increased sequentially with increasing chain length from 7.10(-7) to 4.10(-4) cm/s, respectively, at 25 degrees C. The permeability of methylamine was similar to that of ethylamine (1.10(-6) cm/s at 25 degrees C) and exhibited a relatively smaller entropy increase. The enthalpy of activation for the transfer reaction was high for all amine derivatives (20 kcal/mol). The entropy of activation increased with increasing chain length. The results indicate that the rate of diffusion is dominated by the partition into the membrane. Methylamine, being the smallest molecule in this series, can probably diffuse also through vacancies formed by the internal motions of the lipid chains.
通过使用1:2的钆-乙二胺四乙酸络合物作为弛豫试剂的1H-核磁共振光谱法，测定了前五种正烷基胺在卵磷脂囊泡中的扩散活化汇率、焓和熵。由乙基到戊基衍生物的交换速率所确定的渗透率，在25℃下随着链长的增加而依次增加，分别从7×10⁻⁷增加到4×10⁻⁴cm/s。甲胺的渗透率与乙胺相似（在25℃下为1×10⁻⁶cm/s），且熵增加相对较小。所有胺衍生物的转移反应活化焓都很高（20千卡/摩尔）。活化熵随着链长的增加而增加。结果表明，扩散速率主要由在膜中的分配所主导。甲胺作为该系列中最小的分子，可能也能通过脂质链内部运动形成的空位进行扩散。
