Lineweaver-Burk plot
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In biochemistry, the Lineweaver-Burk plot (or double reciprocal plot) is a graphical representation of the Lineweaver-Burk equation of enzyme kinetics, described by Hans Lineweaver and Dean Burk in 1934[1].
Derivation
The plot provides a useful graphical method for analysis of the Michaelis-Menten equation:
![V = V_{max}\frac{[S]}{K_m + [S]}](/images/math/1/3/a/13a6e707391eebde6b0c460f578572a5.png)
Taking the reciprocal gives
![{1 \over V} = {{K_m + [S]} \over V_{max}[S]} = {K_m \over V_{max}} {1 \over [S]} + {1 \over V_{max}}](/images/math/f/5/0/f508fb929e51cffd9722b18877b74fcf.png)
where V is the reaction velocity, Km is the Michaelis-Menten constant, Vmax is the maximum reaction velocity, and [S] is the substrate concentration.
Use
The Lineweaver-Burk plot was widely used to determine important terms in enzyme kinetics, such as Km and Vmax before the wide availability of powerful computers and non-linear regression software, as the y-intercept of such a graph is equivalent to the inverse of Vmax; the x-intercept of the graph represents -1/Km. It also gives a quick, visual impression of the different forms of enzyme inhibition.
The double reciprocal plot distorts the error structure of the data, and it is therefore unreliable for the determination of enzyme kinetic parameters. Although it is still used for representation of kinetic data[1], non-linear regression or alternative linear forms of the Michaelis-Menten equation such as the Eadie-Hofstee plot are generally used for the calculation of parameters[1].
When used for determining the type of enzyme inhibition, the Lineweaver-Burk plot can distinguish competitive, noncompetitive and uncompetitive inhibitors. Competitive inhibitors have the same y-intercept as uninhibited enzyme (since Vmax is unaffected by competitive inhibitors the inverse of Vmax also doesn't change) but there are different slopes and x-intercepts between the two data sets. Noncompetitive inhibition produces plots with the same x-intercept as uninhibited enzyme (Km is unaffected) but different slopes and y-intercepts. Uncompetitive inhibition causes different intercepts on both the y and x axes but the same slope.
See also
Reference
External links
- NIH guide, enzyme assay development and analysis
Proteins: enzymes | |
|---|---|
| Topics | Active site - Allosteric regulation - Binding site - Catalytically perfect enzyme - Coenzyme - Cofactor - Cooperativity - EC number Enzyme catalysis - Enzyme inhibitor - Enzyme kinetics - Lineweaver-Burk plot - Michaelis-Menten kinetics - List of enzymes |
| Types | EC1 Oxidoreductases/list - EC2 Transferases/list - EC3 Hydrolases/list - EC4 Lyases/list - EC5 Isomerases/list - EC6 Ligases/list |
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
