Gabaldon María
Centro de Investigación, Hospital La Fe, Avenida Campanar 21, 46009 Valencia, Spain.
Int J Biol Macromol. 2009 Jan 1;44(1):43-50. doi: 10.1016/j.ijbiomac.2008.09.020. Epub 2008 Oct 15.
Albumin isomerizes to the aged form in the presence of cysteine at pH 8.9 and low ionic strength. Albumins with a high fatty acid and Cu(II) content do not produce isomers, and recover this capacity after an acid expansion. Isomers have the free thiol group fully oxidized (non-mercaptalbumin) and have been isolated for the first time from aged albumins by anion and cation exchange chromatography. Isomers have a higher susceptibility to limited tryptic digestion and show a decrease in the fluorescence of bound dansylamide, a typical marker of site I. Aging in the presence of phenylarsine oxide, which complexes vicinal thiols, impairs the formation of isomers and increases the free -SH groups of albumin.
在pH 8.9和低离子强度条件下，白蛋白在半胱氨酸存在时会异构化为老化形式。具有高脂肪酸和铜（II）含量的白蛋白不会产生异构体，在酸膨胀后恢复这种能力。异构体的游离巯基完全氧化（非巯基白蛋白），并首次通过阴离子和阳离子交换色谱从老化白蛋白中分离出来。异构体对有限的胰蛋白酶消化更敏感，并且结合丹磺酰胺（位点I的典型标记物）的荧光会降低。在苯胂氧化物存在下老化会使邻位巯基络合，从而损害异构体的形成并增加白蛋白的游离-SH基团。
