DiCola D, Polidoro G, Di Ilio G, Del Boccia C, Politi L, Scandurra R
Mol Cell Biochem. 1976 Apr 28;11(2):97-101. doi: 10.1007/BF01792790.
Cytoplasmic aspartate aminotransferase from beef kidney loses 25% of its activity on nitration with tetranitromethane while the apoenzyme about 95%. In the holoenzyme 0.5 tyrosine residue and 1.0 tyrosine residue in the apoenzyme are nitrated per enzyme protomer. In addition 1 cysteine residue per protomer is oxidized in both. The presence of substrates, alpha-ketoglutarate and glutamate, both at ten times their Km values, does not change these results. Mercaptoethanol does not affect the residual activity of either the nitrated holo or apoenzyme. Dithionite abolishes the activity of the nitrated holoenzyme by reducing tha coenzyme moiety. It has no effect on the native holoenzyme or on either the native or nitroapoenzyme.
来自牛肾的细胞质天冬氨酸转氨酶在用四硝基甲烷硝化时活性丧失25%，而脱辅酶丧失约95%。在全酶中，每个酶原硝化0.5个酪氨酸残基，在脱辅酶中硝化1.0个酪氨酸残基。此外，两种酶中每个酶原的1个半胱氨酸残基均被氧化。底物α-酮戊二酸和谷氨酸均以其Km值的10倍存在时，不会改变这些结果。巯基乙醇不影响硝化全酶或脱辅酶的残余活性。连二亚硫酸盐通过还原辅酶部分而消除硝化全酶的活性。它对天然全酶或天然或硝化脱辅酶均无影响。
