Meussdoerffer F, Afting E G, Holzer H
Hoppe Seylers Z Physiol Chem. 1978 Aug;359(8):993-7. doi: 10.1515/bchm2.1978.359.2.993.
The molecular weight of the proteinase A inhibitor IA3 from baker's yeast was determined by different methods. From gel-filtration experiments, a molecular weight of 19 000 was calculated for the native inhibitor, while under denaturing conditions a molecular weight of 7400 was found. From electrophoretic experiments with the native protein, a molecular weight of 9000 was calculated. A similar value was obtained from the analytical ultracentrifuge, even at a protein concentration of 12 mg/ml. The diffusion coefficient and the partial specific volume were measured and from these data the frictional ratio and the Stokes radius were calculated. These parameters indicate that the relatively high apparent molecular weight calculated from the gel-filtration experiments is caused by the assymetric shape of the inhibitor molecule rather than by an aggregation of subunits.
采用不同方法测定了来自面包酵母的蛋白酶A抑制剂IA3的分子量。通过凝胶过滤实验，计算出天然抑制剂的分子量为19000，而在变性条件下，测得分子量为7400。对天然蛋白质进行电泳实验，计算出分子量为9000。即使在蛋白质浓度为12mg/ml时，用分析超速离心机也得到了类似的值。测量了扩散系数和比容，并根据这些数据计算出摩擦系数和斯托克斯半径。这些参数表明，凝胶过滤实验计算出的相对较高的表观分子量是由抑制剂分子的不对称形状引起的，而不是亚基的聚集。
