Hamm H H, Seubert W
Z Naturforsch C Biosci. 1977 Sep-Oct;32(9-10):777-80. doi: 10.1515/znc-1977-9-1019.
The mechanism of in vitro inactivation and ATP-dependent rapid reactivation of rat liver tyrosine aminotransferase by a membrane-bound system from rat liver and kidney cortex and the nucleotide specificity of this process was investigated using partially purified tyrosine amino-transferase as a substrate. Adenosine 5'-triphosphate (ATP) could be replaced by guanosine 5'-triphosphate (GTP), Whereas inosine 5'-triphosphate (ITP) was less effective. During reactivation [gamma-32P]ATP was incorporated into the enzyme and not excorporated by incubation of the labeled enzyme with excess non-radioative ATP. Inactivation of labeled tyrosine aminotransferase by a particulate fraction led to a decrease protein-bound radioactivity concomitant with an increase of [32P]orthophosphate. This points to a phosphorylation and dephosphorylation mechanism in the regulation of tyrosine aminotransferase activity.
利用部分纯化的酪氨酸转氨酶作为底物，研究了大鼠肝脏和肾皮质的膜结合系统对大鼠肝脏酪氨酸转氨酶的体外失活及ATP依赖性快速复活机制，以及该过程的核苷酸特异性。三磷酸腺苷（ATP）可被三磷酸鸟苷（GTP）替代，而三磷酸肌苷（ITP）的效果较差。在复活过程中，[γ-32P]ATP掺入酶中，且用过量非放射性ATP孵育标记酶时不会被排出。微粒部分使标记的酪氨酸转氨酶失活会导致蛋白质结合放射性降低，同时伴随着[32P]正磷酸盐增加。这表明酪氨酸转氨酶活性调节中存在磷酸化和去磷酸化机制。
