Kulkarni G, Cook P F, Harris B G
Department of Biochemistry & Molecular Biology, Texas College of Osteopathic Medicine/University of North Texas, Fort Worth 76107.
Arch Biochem Biophys. 1993 Jan;300(1):231-7. doi: 10.1006/abbi.1993.1032.
The nucleotide sequence of a full-length cDNA encoding NAD(+)-malic enzyme from the parasitic nematode Ascaris suum was determined. The entire sequence of 2269 bases comprises a 5'-leader, a single open reading frame of 1851 bases, and the complete 3'-noncoding region of 340 bases. The first 12 amino acids of the translated sequence are hydrophobic, typical of mitochondrial translocation signals, and do not appear in the purified mature protein. The mature protein contains 605 amino acids and has a molecular mass of 68,478 Da. The amino acid sequences of tryptic peptides from the purified protein and also the N-terminal sequence show excellent correspondence with the translated nucleotide sequence. Comparison of the amino acid sequence of the ascarid protein with the human and rat liver NAD(+)-malic enzymes reveals highly conserved regions interrupted with long stretches of lesser homologous sequences. Structural motifs such as the putative nucleotide binding domains and also the malate binding site are clearly identified by alignment of the three protein sequences.
测定了来自寄生线虫猪蛔虫的编码NAD(+) - 苹果酸酶的全长cDNA的核苷酸序列。2269个碱基的完整序列包括一个5'前导序列、一个1851个碱基的单一开放阅读框以及340个碱基的完整3'非编码区。翻译序列的前12个氨基酸具有疏水性，这是线粒体转运信号的典型特征，在纯化的成熟蛋白中不存在。成熟蛋白包含605个氨基酸，分子量为68478道尔顿。来自纯化蛋白的胰蛋白酶肽段的氨基酸序列以及N端序列与翻译后的核苷酸序列显示出极好的一致性。将蛔虫蛋白的氨基酸序列与人和大鼠肝脏的NAD(+) - 苹果酸酶进行比较，发现高度保守区域被长段同源性较低的序列打断。通过对这三种蛋白质序列的比对，明确鉴定出了如假定的核苷酸结合结构域以及苹果酸结合位点等结构基序。
