Lineweaver-Burk plot
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:
- <math>V = V_{max}\frac{[S]}{K_m + [S]} </math>
Taking the reciprocal gives
- <math>{1 \over V} = {{K_m + [S]} \over V_{max}[S]} = {K_m \over V_{max}} {1 \over [S]} + {1 \over V_{max}}</math>
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[2], 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[3].
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
- ↑ Lineweaver, H; and Burk, D. (1934). "The Determination of Enzyme Dissociation Constants". Journal of the American Chemical Society 56: 658—666.
- ↑ Serap Doğan, Pınar Turan and Mehmet Doğan (December 2006). "Some kinetic properties of polyphenol oxidase from Thymbra spicata L. var. spicata". Process Biochemistry 41 (12): 2379-2385. doi:10.1016/j.jchromb.2006.07.006.
- ↑ Greco, W. R. and Hakala, M. T., (1979,). "Evaluation of methods for estimating the dissociation constant of tight binding enzyme inhibitors,". J. Biol. Chem., 254,: 12104-12109,.
External links
- NIH guide, enzyme assay development and analysis
Proteins: enzymes | |
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| 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 |
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