Kumar M A, Davidson V L
Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4505.
Biotechniques. 1992 Feb;12(2):198, 200, 202.
Amicyanin is a monomeric protein of known structure which possesses a single cysteine that serves as a ligand to copper in its native state. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of amicyanin after denaturation in the presence and absence of beta-mercaptoethanol, however, indicated that this protein was a dimer which was covalently linked by interchain disulfide bonds. This artifact was caused by exposure during denaturation of the free cysteine that normally binds copper and subsequent formation of a disulfide bond between otherwise unliked monomers. This phenomenon is documented, and additional control experiments are proposed to identify and avoid this artifact when using SDS-PAGE to analyze the subunit structure of proteins.
天蓝蛋白是一种结构已知的单体蛋白，在其天然状态下有一个半胱氨酸作为铜的配体。然而，在有和没有β-巯基乙醇存在的情况下对变性后的天蓝蛋白进行十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）分析表明，该蛋白是由链间二硫键共价连接的二聚体。这种假象是由于在变性过程中，正常情况下结合铜的游离半胱氨酸暴露，随后在原本不相关的单体之间形成二硫键所致。记录了这一现象，并提出了额外的对照实验，以在使用SDS-PAGE分析蛋白质亚基结构时识别并避免这种假象。
