Williams R S, Trumbly R J, MacColl R, Trimble R B, Maley F
J Biol Chem. 1985 Oct 25;260(24):13334-41.
Saccharomyces cerevisiae external and internal invertases have been amplified by introducing the normal and modified SUC2 genes into yeast multicopy plasmids, which were then used to transform a yeast strain resistant to repression by glucose. Amino acid compositional analysis of these enzymes, in addition to end group sequencing, confirmed the DNA sequence data of Taussig and Carlson (Taussig, R., and Carlson, M. (1983) Nucleic Acids Res. 11, 1943-1954), indicating that both enzymes were encoded in the same gene. Comparison of the properties of carbohydrate-containing external invertase and its nonglycosylated internal form revealed that although the carbohydrate did not appear to influence the conformation of the peptide backbone, as determined by circular dichroism analyses, its presence considerably enhanced the ability of guanidine HCl-denatured external invertase to be renatured relative to internal invertase. The Mr of the internal enzymes was found to be greatly dependent on pH with the enzyme being a monomer at pH 9.4, a dimer at pH 8.3, and an apparent octamer at pH 4.9.
通过将正常和修饰的SUC2基因导入酵母多拷贝质粒，扩增了酿酒酵母的外切和内切蔗糖酶，然后用这些质粒转化对葡萄糖阻遏有抗性的酵母菌株。除了末端基团测序外，对这些酶的氨基酸组成分析证实了陶西格和卡尔森的DNA序列数据（陶西格，R.，和卡尔森，M.（1983年）《核酸研究》11，1943 - 1954），表明这两种酶都由同一个基因编码。对含糖外切蔗糖酶及其非糖基化内切形式的性质进行比较后发现，尽管通过圆二色性分析确定碳水化合物似乎不影响肽主链的构象，但其存在相对于内切蔗糖酶大大增强了盐酸胍变性外切蔗糖酶复性的能力。发现内切酶的分子量高度依赖于pH值，该酶在pH 9.4时为单体，在pH 8.3时为二聚体，在pH 4.9时为明显的八聚体。
