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Lidstrom:Buffers: Difference between revisions
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→How to chose a buffer for enzyme assays
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* '''Borate''' | * '''Borate''' | ||
** Borate has the disadvantage of complexing with vic diols, which included many carbohydrates and the ribose moitey of nucleotides. It would be best avoided when assaying enzymes using NAD(P) or other nucleotides. | ** Borate has the disadvantage of complexing with vic diols, which included many carbohydrates and the ribose moitey of nucleotides. It would be best avoided when assaying enzymes using NAD(P) or other nucleotides. | ||
* '''Tris/maleate''' | |||
** Tris/maleate has been used to cover a wide span of pH from 5.8-8.6, but it does not buffer uniformly between the two pKs, and maleate absorbs in the UV region of the spectrum. | |||
* '''Barbituric acid''' | |||
** Barbituric acid buffer used to be extensively used in the range pH 7-9. Apart from being poisonous and inhibiting oxidative phosphorylation, it has the disadvantages o being unstable and of absorbing in the UV region. | |||
* '''Citric acid''' | |||
** Citric acid binds some proteins and also complexes many metal ions. It's pK<sub>a</sub> values are influenced by the ionic strength of the buffer more than most. | |||
*'''Tris""" | |||
** Tris, although widely used, has the disadvantage common to other primary amine buffers of veing reactive and forming Schiff bases with aldehyde and ketones. | |||
* '''Glycylglycine''' | |||
** Glycylglycine binds cetain metal ions; e.g. Mn<sup>2+</sup> and Cu<sup>2+</sup>; it may be degraded by peptidases, it is epxensive, and generally has no advantages over the cheaper Tricine. | |||
* '''Bicarbonate''' | |||
** Bicarbonate buffer has the disadvantage of haivng to be used in a closed sysem to avoid the loss of carbonic acid as CO<sub>2</sub>. | |||
[[image:Buffers For Enzyme Assays.jpg|thumb|upright=1.6|center|buffers for enzyme assays, from [http://www.amazon.com/Enzyme-Assays-Practical-Approach-Series/dp/0199631425/ref=sr_1_1?ie=UTF8&qid=1383921457&sr=8-1&keywords=0199631425 ISBN 0-19-963142-5 | |||
[[image:Buffers For Enzyme Assays.jpg|thumb|upright=1.6|center|buffers for enzyme assays, from [http://www.amazon.com/Enzyme-Assays-Practical-Approach-Series/dp/0199631425/ref=sr_1_1?ie=UTF8&qid=1383921457&sr=8-1&keywords=0199631425 ISBN 0-19-963142-5]]] | |||
== Resources== | == Resources== | ||
