Adachi S, Uesugi T, Kamisaka K
Arch Biochem Biophys. 1985 Sep;241(2):486-93. doi: 10.1016/0003-9861(85)90574-0.
The stabilities of bilirubin (BR) glucuronide, monoglucuronide (BMG), and diglucuronide (BDG) were studied under various conditions by HPLC. In aqueous media, BMG showed a pronounced lability and was easily transformed into equimolar BDG and BR. It was proved by direct analysis of tetrapyrrole isomers that BDG and BR were formed from dipyrrole exchange of BMG molecules. All reducing agents examined (sodium ascorbate, cysteine, GSH, dithiothreitol, NADH, and NADPH) suppressed the transformation of BMG into BDG and BR. Bovine serum albumin and rat liver cytosol fractions also stabilized BMG strongly. BDG was fairly stable in aqueous media as compared with BMG. When BMG was incubated both with and without liver plasma membranes (N2 fraction) from Wistar rats, the formation rates of BDG and BR in both incubation mixtures were exactly the same. The composition of BDG and BR isomers was the same in both mixtures. Also, heat denaturation of the plasma membranes did not affect formation rates. Moreover, the reaction was completely inhibited by sodium ascorbate. These findings indicate that rat liver plasma membranes have no enzyme activity for BDG formation from BMG.
通过高效液相色谱法（HPLC）研究了胆红素（BR）葡糖醛酸苷、单葡糖醛酸苷（BMG）和双葡糖醛酸苷（BDG）在各种条件下的稳定性。在水性介质中，BMG表现出明显的不稳定性，容易转化为等摩尔的BDG和BR。通过对四吡咯异构体的直接分析证明，BDG和BR是由BMG分子的二吡咯交换形成的。所检测的所有还原剂（抗坏血酸钠、半胱氨酸、谷胱甘肽、二硫苏糖醇、NADH和NADPH）均抑制了BMG向BDG和BR的转化。牛血清白蛋白和大鼠肝脏胞质溶胶组分也能强烈稳定BMG。与BMG相比，BDG在水性介质中相当稳定。当BMG在有和没有来自Wistar大鼠的肝细胞膜（N2组分）的情况下孵育时，两种孵育混合物中BDG和BR的形成速率完全相同。两种混合物中BDG和BR异构体的组成相同。此外，细胞膜的热变性不影响形成速率。而且，该反应被抗坏血酸钠完全抑制。这些发现表明，大鼠肝细胞膜没有将BMG转化为BDG的酶活性。
