Duff S M, Kalambur S, Boyle-Roden E
Department of Nutrition and Food Science, University of Maryland, College Park, Maryland 20742, USA.
J Nutr. 2001 Mar;131(3):774-8. doi: 10.1093/jn/131.3.774.
We investigated the interaction of bovine serum albumin (BSA) and monoolein (MO) and estimated the number of BSA binding sites for the alpha- and beta-isomers of MO. The turbidity of increasing concentrations of aqueous dispersions of alpha-MO and beta-MO in the presence and absence of BSA was measured in triplicate by absorption spectrophotometry. Aqueous dispersions of [13C(1)]MO and [13C(1)]MO/BSA mixtures at molar ratios of 1:1, 3:1 and 5:1 were analyzed in duplicate by [13C]nuclear magnetic resonance (NMR) at pH 7.4 and 36 degrees C. BSA bound significantly more beta-MO than alpha-MO at 15 min: 5.4 +/- 0.42 and 3.3 +/- 0.60 mol MO/mol BSA, respectively (P: < 0.05). [13C]NMR spectra of the 1:1 molar ratio of [13C(1)]MO /BSA exhibited a single carbonyl peak at 175.19 ppm, whereas spectra of 3:1 and 5:1 molar ratios exhibited three peaks between 172 and 174 (ppm), each distinct from carbonyl resonances of either [13C(1)]MO dispersed in water, 176.72 (ppm) or BSA alone. The intensities of individual peaks, but not their chemical shift values, varied between 3:1 and 5:1 molar ratios, indicating that BSA has at least three MO binding sites and may bind up to five molecules of MO per molecule. This study confirms that serum albumin binds MO in vitro and supports the theory that albumin transports monoglycerides produced by lipoprotein lipase hydrolysis of triglyceride.
我们研究了牛血清白蛋白（BSA）与单油酸甘油酯（MO）的相互作用，并估算了MO的α-和β-异构体的BSA结合位点数量。通过吸收分光光度法，一式三份测量了在有和没有BSA存在的情况下，α-MO和β-MO的浓度不断增加的水分散体的浊度。在pH 7.4和36℃下，通过[13C]核磁共振（NMR）对摩尔比为1:1、3:1和5:1的[13C(1)]MO水溶液和[13C(1)]MO/BSA混合物进行了一式两份分析。在15分钟时，BSA结合的β-MO明显多于α-MO：分别为5.4±0.42和3.3±0.60摩尔MO/摩尔BSA（P：<0.05）。[13C(1)]MO /BSA摩尔比为1:1的[13C]NMR光谱在175.19 ppm处显示出一个单一的羰基峰，而3:1和5:1摩尔比的光谱在172至174（ppm）之间显示出三个峰，每个峰都与分散在水中的[13C(1)]MO（176.72 ppm）或单独的BSA的羰基共振不同。在3:1和5:1摩尔比之间，各个峰的强度而不是其化学位移值有所变化，这表明BSA至少有三个MO结合位点，并且每个分子可能结合多达五个MO分子。这项研究证实血清白蛋白在体外与MO结合，并支持白蛋白转运由脂蛋白脂肪酶水解甘油三酯产生的甘油单酯的理论。
