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Understanding Enzyme saturation curve
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Alastair Croxton
Understanding Enzyme saturation curve
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According to Lehninger (2000):
At relatively low concentrations of substrate, V0 increases almost linearly with an increase in [S]. At higher substrate concentrations, V0 increases by smaller and smaller amounts in response to increases in [S]. Finally, a point is reached beyond which increases in V0 are vanishingly small as [S] increases. This plateau-like V0 region is close to the maximum velocity, Vmax. (emphasis mine)
This is the image that comes after that paragraph:
FIGURE 6–11 Effect of substrate concentration on the initial velocity of an enzyme-catalyzed reaction. Vmax is extrapolated from the plot, because V0 approaches but never quite reaches Vmax. The substrate concentration at which V0 is half maximal is Km, the Michaelis constant.
Thus, regarding your questions ("Why don't we achieve enzyme saturation linearly? Why do we go through that curved phase( region B )?"), the answer is: there is no line, it's all curved.
Source:
Lehninger, A., Nelson, D. and Cox, M. (2000). Principles of biochemistry. New York: Worth Publishers.
At relatively low concentrations of substrate, V0 increases almost linearly with an increase in [S]. At higher substrate concentrations, V0 increases by smaller and smaller amounts in response to increases in [S]. Finally, a point is reached beyond which increases in V0 are vanishingly small as [S] increases. This plateau-like V0 region is close to the maximum velocity, Vmax. (emphasis mine)
This is the image that comes after that paragraph:
FIGURE 6–11 Effect of substrate concentration on the initial velocity of an enzyme-catalyzed reaction. Vmax is extrapolated from the plot, because V0 approaches but never quite reaches Vmax. The substrate concentration at which V0 is half maximal is Km, the Michaelis constant.
Thus, regarding your questions ("Why don't we achieve enzyme saturation linearly? Why do we go through that curved phase( region B )?"), the answer is: there is no line, it's all curved.
Source:
Lehninger, A., Nelson, D. and Cox, M. (2000). Principles of biochemistry. New York: Worth Publishers.
But is this really an answer to the question? Despite his mistaken diagram, the basic point he is asking is why the curve is hyperbolic rather than linear. This, of course is trivial and answered in all texts, but an unhelpful answer really isn't a lot of use. Surely better to scrub the question.More
. Normally, nobody writes another answer if there is already an accepted one. So, by unmarking my answer, you get more chances of receiving the answer you wish, whatever it is.More
Your image is not correct.
According to Lehninger (2000):
This is the image that comes after that paragraph:
FIGURE 6–11 Effect of substrate concentration on the initial velocity of an enzyme-catalyzed reaction. Vmax is extrapolated from the plot, because V0 approaches but never quite reaches Vmax. The substrate concentration at which V0 is half maximal is Km, the Michaelis constant.
Thus, regarding your questions ("Why don't we achieve enzyme saturation linearly? Why do we go through that curved phase( region B )?"), the answer is: there is no line, it's all curved.
Source:
Your image is not correct.
According to Lehninger (2000):
This is the image that comes after that paragraph:
FIGURE 6–11 Effect of substrate concentration on the initial velocity of an enzyme-catalyzed reaction. Vmax is extrapolated from the plot, because V0 approaches but never quite reaches Vmax. The substrate concentration at which V0 is half maximal is Km, the Michaelis constant.
Thus, regarding your questions ("Why don't we achieve enzyme saturation linearly? Why do we go through that curved phase( region B )?"), the answer is: there is no line, it's all curved.
Source:
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