Toyama S, Misono H, Soda K
Biochim Biophys Acta. 1978 Mar 14;523(1):75-81. doi: 10.1016/0005-2744(78)90010-4.
The activity of taurine: alpha-ketoglutarate aminotransferase (taurine: 2-oxoglutarate aminotransferase, EC 2.6.1.55) from Achromobacter superficialis is significantly diminished by treatment of the enzyme with (NH4)2SO4 in the course of purification, and recovered by incubation with pyridoxal phosphate at high temperatures such as 60 degrees C. The inactive form of enzyme absorbing at 280 and 345 nm contains 3 mol of pyridoxal phosphate per mol. The activated enzyme contains additional 1 mol of pyridoxal phosphate with a maximum at 430 nm. This peak is shifted to about 400 nm as a shoulder by dialysis of the enzyme, but the activity is not influenced. The inactive form is regarded as a partially resolved form, i.e. a semiapoenzyme. The enzyme catalyzes transamination of various omega-amino aicds with alpha-ketoglutarate, which is the exclusive amino acceptor. Hypotaurine, DL-beta-aminoisobutyrate, beta-alanine and taurine are the preferred amino donors. The apparent Michaelis constants are as follows; taurine 12 mM, hypotaurine 16 mM, DL-beta-aminoisobutyrate 11 mM, beta-alanine 17 mM, alpha ketoglutarate 11 mM and pyridoxal phosphate 5 micron.
α-酮戊二酸转氨酶（牛磺酸：2-氧代戊二酸转氨酶，EC 2.6.1.55）在纯化过程中用硫酸铵处理后活性显著降低，通过在高温（如60℃）下与磷酸吡哆醛孵育可恢复活性。在280和345nm处有吸收峰的无活性酶形式每摩尔含有3摩尔磷酸吡哆醛。活化后的酶额外含有1摩尔在430nm处有最大吸收峰的磷酸吡哆醛。通过对该酶进行透析，此峰作为一个肩峰移至约400nm处，但活性不受影响。无活性形式被认为是一种部分解离形式，即半脱辅基酶。该酶催化各种ω-氨基酸与α-酮戊二酸之间的转氨作用，α-酮戊二酸是唯一的氨基受体。亚牛磺酸、DL-β-氨基异丁酸、β-丙氨酸和牛磺酸是优先的氨基供体。表观米氏常数如下：牛磺酸12mM，亚牛磺酸16mM，DL-β-氨基异丁酸11mM，β-丙氨酸17mM，α-酮戊二酸11mM，磷酸吡哆醛5μM。
