Dirr H W
Department of Biochemistry, Rand Afrikaans University, Johannesburg, South Africa.
Biochem Int. 1987 Apr;14(4):727-33.
The influence of pH and long-chain fatty acids on the interaction between aflatoxin B1 and human albumin was investigated by fluorescence spectroscopy. Both the binding of aflatoxin B1 to albumin and the fluorescence of albumin-bound aflatoxin are pH-dependent over the pH range of 6-9.5. The data indicates that the carcinogen has a higher affinity for the basic(B) than for the neutral(N) conformation of human albumin. Palmitic, stearic and oleic acids up to a molar ratio of 2 over albumin, increases the binding strength of aflatoxin B1 by means of an allosteric mechanism. Furthermore, the pH-dependence of the aflatoxin-albumin interaction is affected by the presence of oleic acid by narrowing the pH range over which the dependence occurs. At molar ratios of oleic acid to albumin in excess of 4.25 at pH6, 3.1 at pH7.4 and 2.4 at pH9 cause a decrease in aflatoxin B1 fluorescence as a result of reduced binding to albumin.
通过荧光光谱法研究了pH值和长链脂肪酸对黄曲霉毒素B1与人血清白蛋白相互作用的影响。在pH值6 - 9.5范围内，黄曲霉毒素B1与白蛋白的结合以及与白蛋白结合的黄曲霉毒素的荧光均依赖于pH值。数据表明，致癌物对人血清白蛋白的碱性（B）构象的亲和力高于中性（N）构象。棕榈酸、硬脂酸和油酸与白蛋白的摩尔比高达2时，通过变构机制增加了黄曲霉毒素B1的结合强度。此外，油酸的存在通过缩小发生依赖性的pH范围，影响了黄曲霉毒素 - 白蛋白相互作用的pH依赖性。在pH6时，油酸与白蛋白的摩尔比超过4.25，在pH7.4时超过3.1，在pH9时超过2.4，由于与白蛋白的结合减少，导致黄曲霉毒素B1荧光降低。
