Jouenne E, Crouzet J
Laboratoire de Génie Biologique et Sciences des Aliments, Equipe de Microbiologie et Biochimie Industrielles, Associée à l'INRA, Université de Montpellier II, 34095 Montpellier Cedex 05, France.
J Agric Food Chem. 2000 Nov;48(11):5396-400. doi: 10.1021/jf000423k.
Apparent binding constants of aroma compounds limonene, alpha- and beta-ionone, and terpenyl acetate, with beta-lactoglobulin (BLG), were determined, using dynamic coupled column liquid chromatography, for pH values varying from 3 to 11. K(a) values varied from 2.61 to 3.21 x 10(3) M(-1) for limonene, indicating a strong interaction with BLG. Similarly, significant and close apparent binding constants were obtained for alpha- and beta-ionone, 1.7 x 10(2) and 4.5 to 5.4 x 10(2) M(-1), respectively. These data indicated that a similar mechanism is involved for the binding of these two molecules. The weaker values obtained at low pH, for alpha-ionone relative to beta-ionone, can be explained by the existence of steric hindrance. An increase of the apparent binding constant was observed, for all the compounds studied, when the pH was increased from 3 to 9. At this pH, an apparent binding constant was obtained for terpenyl acetate (1.04 x 10(2) M(-1)), whereas this determination was not possible at pH 3 and 6. The apparent binding constant increase was in agreement with the decrease of aroma compound relative activity coefficient in the presence of BLG, previously observed at this pH. It indicated a best accessibility to the same binding site. The binding constants of all the aroma compounds studied decreased at pH 11 as a result of the important release of the BLG structure previously reported.
采用动态耦合柱液相色谱法，测定了柠檬烯、α-紫罗兰酮、β-紫罗兰酮和乙酸萜品酯等香气化合物在pH值为3至11范围内与β-乳球蛋白（BLG）的表观结合常数。柠檬烯的K(a)值在2.61至3.21×10³ M⁻¹之间，表明其与BLG有强烈相互作用。同样，α-紫罗兰酮和β-紫罗兰酮分别获得了显著且相近的表观结合常数，分别为1.7×10²和4.5至5.4×10² M⁻¹。这些数据表明这两种分子的结合涉及相似机制。在低pH值下，α-紫罗兰酮相对于β-紫罗兰酮获得的较弱值可通过空间位阻的存在来解释。当pH值从3增加到9时，观察到所有研究化合物的表观结合常数均增加。在此pH值下，获得了乙酸萜品酯的表观结合常数（1.04×10² M⁻¹），而在pH值为3和6时无法进行此测定。表观结合常数的增加与先前在此pH值下观察到的在BLG存在下香气化合物相对活度系数的降低一致。这表明对同一结合位点的可及性最佳。由于先前报道的BLG结构的重要释放，所有研究的香气化合物的结合常数在pH值为11时均降低。
