Kochhar S, Kochhar V K, Sane P V
National Botanical Research Institute, Lucknow, India.
Biochem Mol Biol Int. 1998 Apr;44(4):795-806. doi: 10.1080/15216549800201842.
The lysine-sensitive isoenzyme of aspartate kinase was purified to homogeneity from spinach leaves and its subunit composition was studied. The purified preparation had an apparent molecular mass of 280,000 and separated into two subunits- a large subunit with molecular mass of 53,000 and smaller subunit with molecular mass of 17,000 by urea treatment and SDS PAGE. The enzyme molecule has subunit composition of 4 large and 4 small subunits. The activity of the large subunit was stimulated more than two fold by the addition of small subunit and the stimulated activity was inhibited by EGTA. This inhibition could be reversed by Ca++. Further characteristics of the smaller subunit such as heat stability, behavior on ion exchange chromatography, elctrophoretic mobility on polyacrylamide gels, amino acid composition and pattern, presence of trimethyl lysine, its ability to activate other calmodulin stimulated enzymes and its calmodulin-like nature in RIA tests suggested that this subunit is identical to calmodulin.
从菠菜叶中纯化出天冬氨酸激酶的赖氨酸敏感同工酶，并对其亚基组成进行了研究。纯化后的制剂表观分子量为280,000，经尿素处理和SDS-PAGE分离为两个亚基——一个分子量为53,000的大亚基和一个分子量为17,000的小亚基。该酶分子具有4个大亚基和4个小亚基的亚基组成。大亚基的活性通过添加小亚基被刺激了两倍多，且刺激后的活性被EGTA抑制。这种抑制作用可被Ca++逆转。小亚基的进一步特性，如热稳定性、离子交换色谱行为、聚丙烯酰胺凝胶上的电泳迁移率、氨基酸组成和模式、三甲基赖氨酸的存在、其激活其他钙调蛋白刺激酶的能力以及在放射免疫分析测试中的钙调蛋白样性质，表明该亚基与钙调蛋白相同。
