Takeshita H, Yasuda T, Iida R, Nakajima T, Hosomi O, Nakashima Y, Mori S, Nomoto H, Kishi K
Department of Legal Medicine, Gunma University School of Medicine, Maebashi, Japan.
FEBS Lett. 1998 Nov 27;440(1-2):239-42. doi: 10.1016/s0014-5793(98)01456-2.
We purified DNase II from human liver to apparent homogeneity. The N-terminal amino acid sequences of each of three components constituting the purified mature enzyme were then separately determined by automatic Edman degradation. A combination of this chemical information and the previously reported nucleotide sequence of the cDNA encoding human DNase II [Yasuda et al. (1998) J. Biol. Chem. 273, 2610-2626] allowed detailed elucidation of the enzyme's subunit structure: human DNase II was composed of three non-identical subunits, a propeptide, proprotein and mature protein, following a signal peptide. Expression analysis of a series of deletion mutants derived from the cDNA of DNase II in COS-7 cells suggested that although a single large precursor protein may not be necessary for proteolytic maturation, the propeptide region L17-Q46 may play an essential role in generating the active form of the enzyme.
我们从人肝脏中纯化出了具有明显均一性的脱氧核糖核酸酶II（DNase II）。随后，通过自动埃德曼降解法分别测定了构成纯化成熟酶的三种组分各自的N端氨基酸序列。结合这些化学信息以及先前报道的编码人DNase II的cDNA核苷酸序列[安田等人（1998年）《生物化学杂志》273卷，2610 - 2626页]，得以详细阐明该酶的亚基结构：人DNase II由三个不同的亚基组成，即前肽、前体蛋白和成熟蛋白，其排列顺序为信号肽之后跟着这三个亚基。对源自DNase II cDNA的一系列缺失突变体在COS - 7细胞中的表达分析表明，尽管蛋白水解成熟过程可能并不需要单一的大前体蛋白，但前肽区域L17 - Q46可能在生成该酶的活性形式中发挥关键作用。
