Veronese F M, Bevilacqua R, Boccù E, Brown D M
Biochim Biophys Acta. 1976 Aug 12;445(1):1-13. doi: 10.1016/0005-2744(76)90156-x.
Glutamate dehydrogenase (EC 1.4.1.2-4) has been purified and crystallized from the acetone powder of tuna liver. The enzyme has a molecular weight of 333 000 +/- 15 000 as evaluated by sedimentation equilibrium and constists of six identical subunits. Unlike the bovine enzyme the molecular weight does not increase with increasing protein concentration indicating that the tuna enzyme has no tendency to polymerize. The amino acid composition and peptide maps of the tuna and bovine liver enzyme are similar, suggesting considerable homology between the two enzymes. Furthermore, from the tryptic digest a hexadecapeptide containing a lysine residue reactive to pyridoxal 5'-phosphate exhibits the same composition and sequence as the peptide containing the reactive lysine-126 in the sequence of the bovine enzyme. The molecular activity is 25 and 510 mol of substrate per mol enzyme per s, respectively, for the glutamate oxidation and the alpha-ketoglutarate reduction with NAD or NADP as coenzymes. The enzyme is regulated by pyridine nucleotides like other vertebrate enzymes, but it also exhibits some coenzyme specificity, the activity being about fifteen times higher with NAD than with NADP.
谷氨酸脱氢酶（EC 1.4.1.2 - 4）已从金枪鱼肝脏的丙酮粉中纯化并结晶出来。通过沉降平衡评估，该酶的分子量为333000±15000，由六个相同的亚基组成。与牛的酶不同，金枪鱼的酶分子量不会随蛋白质浓度增加而增加，这表明金枪鱼的酶没有聚合倾向。金枪鱼和牛肝脏酶的氨基酸组成及肽图相似，表明这两种酶有相当高的同源性。此外，从胰蛋白酶消化产物中得到的一个含有对磷酸吡哆醛5'-磷酸有反应的赖氨酸残基的十六肽，其组成和序列与牛酶序列中含有反应性赖氨酸 - 126的肽相同。以NAD或NADP为辅酶时，谷氨酸氧化和α - 酮戊二酸还原反应的分子活性分别为每摩尔酶每秒25和510摩尔底物。该酶与其他脊椎动物的酶一样受吡啶核苷酸调节，但也表现出一些辅酶特异性，以NAD作为辅酶时的活性比以NADP时高约15倍。
