Good's buffers 4574507 218889090 2008-06-12T16:55:08Z Shadowfaxes 844945 regime to region '''Good's buffers''' (also '''Good buffers''') are twelve [[buffering agent]]s selected and described by [[Norman Good]] and colleagues in 1966. Good selected the buffers based on a number of criteria which make them candidates for use in [[biochemistry]] and [[biology|biological]] research. Many remain staples in modern biology laboratories. ==Selection criteria== Good sought to identify buffering compounds which met several criteria likely to be of value in biological research. #'''[[pKa|pK<sub>a</sub>]]'''. Because most biological reactions take place at near-neutral [[pH]] between 6 and 8, ideal buffers would have pK<sub>a</sub> values in this region to provide maximum buffering capacity there. #'''Solubility'''. For ease in handling and because biological systems are in aqueous systems, good solubility in water was required. Low solubility in [[nonpolarity|nonpolar]] solvents (fats, oils, and organic solvents) was also considered beneficial, as this would tend to prevent the buffer compound from accumulating in nonpolar compartments in biological systems: [[cell membrane]]s and other cell compartments. #'''Membrane impermeability'''. Ideally, a buffer will not readily pass through cell membranes, this will also reduce the accumulation of buffer compound within [[cell (biology)|cell]]s. #'''Minimal salt effects'''. Highly ionic buffers may cause problems or complications in some biological systems. #'''Well-behaved cation interactions'''. If the buffers form [[complex (chemistry)|complex]]es with [[cation]]ic [[ligand]]s, the complexes formed should remain soluble. Ideally, at least some of the buffering compounds will not form complexes. #'''Stability'''. The buffers should be chemically stable, resisting [[enzyme|enzymatic]] and non-enzymatic degradation. #'''Optical absorbance'''. Buffers should not absorb visible or [[ultraviolet]] light at wavelengths longer than 230 [[nanometer|nm]] so as not to interfere with commonly-used [[spectrophotometry|spectrophotometric]] assays. #'''Ease of preparation'''. Buffers should be easily prepared and purified from inexpensive materials. ==Good's buffers== The twelve buffers selected by Good are tabulated below. {| class="wikitable" ! Buffer !! [[pKa|pK<sub>a</sub>]] at 20°C !! ΔpK<sub>a</sub>/°C |- | [[MES (buffer)|MES]] || 6.15 || -0.011 |- | ADA || 6.6 || -0.011 |- | [[PIPES]] || 6.8 || -0.0085 |- | [[ACES (buffer)|ACES]] || 6.9 || -0.020 |- | Cholamine chloride || 7.1 || -0.027 |- | BES || 7.15 || -0.016 |- | TES || 7.5 || -0.020 |- | [[HEPES]] || 7.55 || -0.014 |- | Acetamidoglycine || 7.7 || - |- | [[Tricine]] || 8.15 || -0.021 |- | Glycinamide || 8.2 || -0.029 |- | Bicine || 8.35 || -0.018 |} ==See also== *[[Buffer solution]] ==References== * {{cite journal | author = N. E. Good, G. D. Winget, W. Winter, T. N. Connolly, S. Izawa and R. M. M. Singh | title = Hydrogen Ion Buffers for Biological Research | year = 1966 | journal = [[Biochemistry (journal)|Biochemistry]] | volume = 5 | issue = 2 | pages = 467–477 | doi = 10.1021/bi00866a011}} ==External Links== *[http://www2.sigmaaldrich.com/suite7/Area_of_Interest/Research_Essentials/Biological_Buffers/Key_Resources/BufferCalc/SigmaAldrich_Buffer_Calculator.html?cm_mmc=wiki-_-social-_-buffer-_-Goods_Buffers Sigma Aldrich Buffer Calculator] - Useful tool to calculate weight, volume, or concentration from molecular weight. {{biochem-stub}} [[Category:Acid-base_chemistry]] [[Category:Buffers]]