Kurzweilová H, Sigler K
Institute of Microbiology, Czech Academy of Sciences, Prague.
Arch Microbiol. 1994;162(3):211-4. doi: 10.1007/BF00314477.
A recently described new method for determination of killer toxin activity was used for kinetic measurements of K1 toxin binding. The cells of the killer sensitive strain Saccharomyces cerevisiae S6 were shown to carry two classes of toxin binding sites differing widely in their half-saturation constants and maximum binding rates. The low-affinity and high-velocity binding component (KT1 = 2.6 x 10(9) L.U./ml, Vmax1 = 0.19 s-1) probably reflects diffusion-limited binding to cell wall receptors; the high-affinity and low-velocity component (KT2 = 3.2 x 10(7) L.U./ml, Vmax2 = 0.03 s-1) presumably indicates the binding of the toxin to plasma membrane receptors. Adsorption of most of the killer toxin K1 to the surface of sensitive cells occurred within 1 min and was virtually complete within 5 min. The amount of toxin that saturated practically all cell receptors was about 600 lethal units (L.U.) per cell of S. cerevisiae S6.
一种最近描述的测定杀伤毒素活性的新方法被用于K1毒素结合的动力学测量。杀伤敏感菌株酿酒酵母S6的细胞显示携带两类毒素结合位点，它们的半饱和常数和最大结合速率差异很大。低亲和力和高速度结合组分（KT1 = 2.6×10⁹ L.U./ml，Vmax1 = 0.19 s⁻¹）可能反映了与细胞壁受体的扩散限制结合；高亲和力和低速度组分（KT2 = 3.2×10⁷ L.U./ml，Vmax2 = 0.03 s⁻¹）大概表明毒素与质膜受体的结合。大多数杀伤毒素K1在1分钟内吸附到敏感细胞表面，5分钟内几乎完全吸附。几乎饱和所有细胞受体的毒素量约为每个酿酒酵母S6细胞600个致死单位（L.U.）。
