Lineweaver-Burk plot
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2008-07-02T05:08:09Z
TimVickers
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Reverted edits by [[Special:Contributions/124.106.217.225|124.106.217.225]] ([[User talk:124.106.217.225|talk]]) to last version by DOI bot
[[Image:Lineweaver-Burke plot.svg|350px|right]]
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<ref>{{cite journal | author = Lineweaver, H and Burk, D. | year = 1934 | title = The Determination of Enzyme Dissociation Constants | journal = Journal of the American Chemical Society | volume = 56 | pages = 658–666 | doi = 10.1021/ja01318a036}}</ref>.
==Derivation==
The plot provides a useful graphical method for analysis of the [[Michaelis-Menten kinetics|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 (the [[reaction rate]]), ''K''<sub>''m''</sub> is the [[Michaelis-Menten constant]], ''V''<sub>max</sub> 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 ''K''<sub>''m''</sub> and ''V''<sub>max</sub> before the wide availability of powerful computers and [[Nonlinear regression|non-linear regression]] software, as the [[y-intercept|''y''-intercept]] of such a graph is equivalent to the inverse of ''V''<sub>max</sub>; the [[x-intercept|''x''-intercept]] of the graph represents −1/''K''<sub>''m''</sub>. 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<ref>{{cite journal
| author = Serap Doğan, Pınar Turan and Mehmet Doğan
| title = Some kinetic properties of polyphenol oxidase from ''Thymbra spicata'' L. var. ''spicata''
| journal = Process Biochemistry
| volume = 41
| issue = 12
| pages = 2379–2385
| date = December 2006
| doi = 10.1016/j.jchromb.2006.07.006}}</ref>, non-linear regression or alternative linear forms of the [[Michaelis-Menten kinetics|Michaelis-Menten]] equation such as the [[Eadie-Hofstee plot]] are generally used for the calculation of parameters<ref>{{cite journal
| author = Greco, W. R. and Hakala, M. T.,
| title = Evaluation of methods for estimating the dissociation constant of tight binding enzyme inhibitors,
| journal = J. Biol. Chem.,
| volume = 254,
| number = 23,
| pages = 12104–12109,
| year = 1979,
| url = http://www.jbc.org/cgi/reprint/254/23/12104.pdf
| pmid = 500698}}</ref>.
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 ''V''<sub>max</sub> is unaffected by competitive inhibitors the inverse of ''V''<sub>max</sub> 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 (''K''<sub>''m''</sub> 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==
* [[Michaelis-Menten kinetics]]
* [[Eadie-Hofstee diagram]]
* [[Hanes-Woolf plot]]
==References==
{{reflist|1}}
== External links ==
* [http://www.ncgc.nih.gov/guidance/section4.html#inhibition-constant NIH guide], enzyme assay development and analysis
{{Enzymes}}
[[Category:Diagrams]]
[[Category:Enzyme kinetics]]
[[es:Diagrama de Lineweaver-Burke]]
[[sr:Лајнвивер-Бурк дијаграм]]