Vorum H, Brodersen R, Kragh-Hansen U, Pedersen A O
Institute of Medical Biochemistry, University of Aarhus, Denmark.
Biochim Biophys Acta. 1992 Jun 22;1126(2):135-42. doi: 10.1016/0005-2760(92)90283-2.
The solubility of the saturated fatty acids lauric, myristic, palmitic, and stearic acid and the unsaturated oleic acid at 37 degrees C in phosphate buffer (pH 7.4) was estimated by using two independent methods. The one was a conventional solubility technique measuring the concentration of dissolved fatty acid in buffer by using radioactive compounds. The other was a dialysis exchange technique monitoring possible aggregation of solvated fatty acid anions by measuring the rate of diffusion of labelled compound across a dialysis membrane under conditions of chemical equilibrium. It was found that the results were strongly dependent on the radiochemical purity of the fatty acids. Using highly purified samples of radioactively labelled fatty acids, the solubility of monomeric laurate was shown to be greater than 500 microM, whereas the solubility of monomeric myristate was found to be 20-30 microM. Palmitate, stearate, and oleate solutions, on the other hand, showed a tendency to aggregation even at concentrations below 1 microM. Special attention was given to palmitate, as a reference compound for long-chain fatty acids, and the solubility of monomeric palmitate was estimated to be lower than 10(-10) M.
采用两种独立的方法估算了饱和脂肪酸月桂酸、肉豆蔻酸、棕榈酸、硬脂酸以及不饱和油酸在37℃下于磷酸盐缓冲液（pH 7.4）中的溶解度。一种是传统的溶解度技术，通过使用放射性化合物来测量缓冲液中溶解脂肪酸的浓度。另一种是透析交换技术，在化学平衡条件下，通过测量标记化合物穿过透析膜的扩散速率来监测溶剂化脂肪酸阴离子可能的聚集情况。结果发现，这些结果强烈依赖于脂肪酸的放射化学纯度。使用放射性标记脂肪酸的高纯度样品时，单体月桂酸盐的溶解度显示大于500微摩尔，而单体肉豆蔻酸盐的溶解度为20 - 30微摩尔。另一方面，棕榈酸盐、硬脂酸盐和油酸盐溶液即使在浓度低于1微摩尔时也显示出聚集的趋势。特别关注了作为长链脂肪酸参考化合物的棕榈酸盐，单体棕榈酸盐的溶解度估计低于10^(-10)摩尔。
