Shimabayashi S, Tanizawa Y, Ishida K
Faculty of Pharmaceutical Sciences, University of Tokushima, Japan.
Chem Pharm Bull (Tokyo). 1991 Sep;39(9):2183-8. doi: 10.1248/cpb.39.2183.
The amount of adsorption of bovine serum albumin (BSA) by hydroxyapatite (HAP) increased with a concentration of CaCl2 due to the bridging effect of Ca2+ between adsorbate BSA and adsorbent HAP. On the other hand, it decreased remarkably with a concentration of K2HPO4. This was explained in terms of the effects of ionic strength and competitive adsorption between inorganic phosphate anion (Pi) and BSA, because BSA is in negatively charged over the examined pHs. A similar effect was observed in the presence of phosphorylated compounds such as phosphoserine, phytate, and phosphorylated polyvinylalcohol. The inhibiting effect of these compounds was stronger than that of their mother compounds (serine, inositol, and polyvinylalcohol). This result shows that phosphate groups bound to the mother compounds interfere with the adsorption of BSA by HAP in the same manner that Pi does. Although the adsorption of BSA was almost irreversible with respect to dilution with water, desorption was performed when these organic phosphorylated compounds were added after the accomplishment of the adsorption of BSA. However, the effective concentration of the phosphorylated compounds for the desorption of BSA was fairly higher than that for the competitive inhibition against the BSA adsorption.
由于Ca2+在吸附质牛血清白蛋白（BSA）和吸附剂羟基磷灰石（HAP）之间的桥连作用，羟基磷灰石（HAP）对牛血清白蛋白（BSA）的吸附量随CaCl2浓度的增加而增加。另一方面，它随K2HPO4浓度的增加而显著降低。这是根据离子强度以及无机磷酸根阴离子（Pi）与BSA之间的竞争吸附作用来解释的，因为在检测的pH范围内BSA带负电荷。在存在磷酸化化合物如磷酸丝氨酸、植酸和磷酸化聚乙烯醇的情况下也观察到了类似的效果。这些化合物的抑制作用比它们的母体化合物（丝氨酸、肌醇和聚乙烯醇）更强。该结果表明，与母体化合物结合的磷酸基团以与Pi相同的方式干扰HAP对BSA的吸附。尽管BSA的吸附相对于用水稀释几乎是不可逆的，但在完成BSA吸附后加入这些有机磷酸化化合物时会发生解吸。然而，用于BSA解吸的磷酸化化合物的有效浓度远高于对BSA吸附的竞争抑制的有效浓度。
