蛋白质浓度计算器
使用布拉德福德法测定蛋白质浓度。
Velocity (Competitive Inhibition)
25.00 umol/min
Velocity (Competitive Inhibition) vs Substrate Concentration [S]
公式
## Enzyme Inhibition Types ### Competitive Inhibition Inhibitor binds to the active site, increasing apparent Km while Vmax remains unchanged. **v = Vmax × [S] / (alpha × Km + [S])**, where alpha = 1 + [I]/Ki ### Noncompetitive Inhibition Inhibitor binds away from the active site, decreasing apparent Vmax while Km remains unchanged. **v = (Vmax/alpha) × [S] / (Km + [S])** Competitive inhibition can be overcome by high substrate concentration; noncompetitive cannot.
计算示例
Vmax=100, Km=50 uM, [I]=20 uM, Ki=10 uM, [S]=50 uM.
- 01alpha = 1 + 20/10 = 3.0
- 02Competitive: v = 100 × 50 / (50 × 3 + 50) = 5000 / 200 = 25.0 umol/min
- 03Noncompetitive: v = (100/3) × 50 / (50 + 50) = 33.33 × 0.5 = 16.67 umol/min
常见问题
How do I distinguish competitive from noncompetitive?
On a Lineweaver-Burk plot: competitive inhibition changes the slope but not the y-intercept (lines converge on y-axis). Noncompetitive changes the y-intercept but not the x-intercept (lines converge on x-axis).
What is uncompetitive inhibition?
Uncompetitive inhibitors bind only to the enzyme-substrate complex, decreasing both apparent Vmax and Km by the same factor. On LB plots, this gives parallel lines.
How is Ki determined experimentally?
Measure kinetics at several inhibitor concentrations. Plot apparent Km (competitive) or apparent 1/Vmax (noncompetitive) vs [I]. The x-intercept of this secondary plot gives -Ki.
学习