Epstein W W, Lever D, Leining L M, Bruenger E, Rilling H C
Department of Chemistry, University of Utah, Salt Lake City 84108.
Proc Natl Acad Sci U S A. 1991 Nov 1;88(21):9668-70. doi: 10.1073/pnas.88.21.9668.
The allylic thioether bond of the prenylcysteines of prenylated proteins has been shown to be cleaved by 2-naphthol under alkaline conditions to yield substituted naphthopyrans. These products are readily resolved from interfering materials by HPLC and have a strongly absorbing chromophore. Thus, this reaction is suitable for quantitative analysis of prenyl substituents of proteins, and we have examined a number of tissues for their content of prenylcysteines. These amino acids are present in mammalian tissues at a concentration of 0.36-1.4 nmol/mg of protein, with a ratio of geranylgeranylcysteine to farnesylcysteine in the range of 4 to 10. Prenylcysteines were also found in the cytosolic fraction of two mouse tissues at about one-third the concentration of the whole organ. The level of these modified amino acids was found to be significantly less in a yeast, a fungus, a brown alga, a higher plant, and an insect. Again, geranylgeranylcysteine is predominant. Prenylcysteines were absent from Escherichia coli but present in an archaebacterium. The prenylcysteine content of mammalian tissue is about 1% of that of cholesterol and about equal to that of ubiquinones and dolichols. Calculations indicate that about 0.5% of all proteins are prenylated.
异戊烯化蛋白的异戊烯基半胱氨酸的烯丙基硫醚键已被证明在碱性条件下可被2-萘酚裂解，生成取代萘并吡喃。这些产物可通过高效液相色谱法（HPLC）轻松地与干扰物质分离，并且具有强烈吸收的发色团。因此，该反应适用于蛋白质异戊烯基取代基的定量分析，我们已经检测了多种组织中异戊烯基半胱氨酸的含量。这些氨基酸在哺乳动物组织中的浓度为0.36 - 1.4 nmol/mg蛋白质，香叶基香叶基半胱氨酸与法尼基半胱氨酸的比例在4到10之间。在两种小鼠组织的胞质部分中也发现了异戊烯基半胱氨酸，其浓度约为整个器官的三分之一。在酵母、真菌、褐藻、高等植物和昆虫中，这些修饰氨基酸的水平明显较低。同样，香叶基香叶基半胱氨酸占主导地位。大肠杆菌中不存在异戊烯基半胱氨酸，但在古细菌中存在。哺乳动物组织中异戊烯基半胱氨酸的含量约为胆固醇含量的1%，与泛醌和多萜醇的含量大致相当。计算表明，所有蛋白质中约有0.5%被异戊烯化。
