Good buffer
A good buffer ( English Good's buffer ) is a buffer used in biochemistry according to the criteria of Norman Good .
properties
Between 1966 and 1980, Norman E. Good and co-workers developed twenty substances for use as buffers. In contrast to other buffer substances, Good buffers should have as few interactions with proteins as possible , high solubility , no diffusion through biomembrane , a buffer range between pH 6 and 8, low toxicity , low UV absorption , independence of the buffer effect from other factors, be inexpensive to manufacture and have metabolic and chemical stability. Some Good buffers are zwitterions , e.g. B. Morpholinoethanesulfonic acid (MES), 3- (N-Morpholino) propanesulfonic acid (MOPS), ADA, BES and Bicine.
Representative
The following table contains the effective pK a values measured by Good at 20 ° C. and at a concentration of about 100 mM. The resulting pH values depend on the concentration and temperature.
| buffer | pK a at 20 ° C | ΔpK a / ° C | Solubility in water at 0 ° C |
|---|---|---|---|
| MES | 6.15 | −0.011 | 0.65M |
| ADA | 6.62 | −0.011 | - |
| PIPES | 6.82 | −0.0085 | - |
| ACES | 6.88 | −0.020 | 0.22M |
| MOPSO | 6.95 | −0.015 | 0.75M |
| Cholamine chloride | 7.10 | −0.027 | 4.2M (as HCl) |
| PUG | 7.15 | −0.013 | high |
| BES | 7.17 | −0.016 | 3.2M |
| TES | 7.5 | −0.020 | 2.6M |
| HEPES | 7.55 | −0.014 | 2.25M |
| DIPSO | 7.6 | −0.015 | 0.24M |
| Acetamidoglycine | 7.7 | - | very high |
| TAPSO | 7.7 | −0.018 | 1.0M |
| POPSO | 7.85 | −0.013 | - |
| HEPPSO | 7.9 | −0.01 | 2.2M |
| HEPPS | 8.1 | −0.015 | high |
| Tricine | 8.15 | −0.021 | 0.8M |
| Glycinamide | 8.2 | −0.029 | 6.4M (as HCl) |
| Bicine | 8.35 | −0.018 | 1.1M |
| TAPS | 8.55 | −0.027 | high |
Three of the Good buffers have little tendency to complex metal ions, MES, MOPS and PIPES. Piperazine -containing buffers (PIPES, HEPES, POPSO and HEPPS) can form radicals and should therefore be avoided in redox studies . Tricine is flavines photo-oxidized and reduces under sunlight the activity of flavones -containing enzymes . The acids of ADA, POPSO and PIPES are sparingly soluble. ADA absorbs UV light below a wavelength of 260 nm, ACES absorbs below 230 nm.
After Good, several other Good buffers were developed, e.g. B. AMPSO , CABS , CHES , CAPS , CAPSO .
Individual evidence
- ^ Norman E. Good, G. Douglas Winget, Wilhelmina Winter, Thomas N. Connolly, Seikichi Izawa, Raizada MM Singh: Hydrogen Ion Buffers for Biological Research . In: Biochemistry . 5, No. 2, 1966, pp. 467-477. doi : 10.1021 / bi00866a011 . PMID 5942950 .
- ^ Norman E. Good, Seikichi Izawa: Hydrogen ion buffers . In: Methods Enzymol. . 24, 1972, pp. 53-68. doi : 10.1016 / 0076-6879 (72) 24054-x . PMID 4206745 .
- ^ WJ Ferguson, KI Braunschweiger, WR Braunschweiger, JR Smith, JJ McCormick, CC Wasmann, NP Jarvis, DH Bell et al .: Hydrogen Ion Buffers for Biological Research . In: Anal Biochem . 104, No. 2, 1980, pp. 300-310. doi : 10.1016 / 0003-2697 (80) 90079-2 . PMID 7446957 .
- ^ R. Goldberg, Kishore, N .; Lennen, R .: Thermodynamic Quantities for the Ionization Reactions of Buffers . In: J. Phys. Chem. Ref. Data . 31, No. 2, 2002, pp. 231-370. doi : 10.1063 / 1.1416902 .
- ↑ JK Grady, ND Chasteen, DC Harris: Radicals from "Good's" buffers . In: Anal. Biochem. . 173, No. 1, 1988, pp. 111-115. doi : 10.1016 / 0003-2697 (88) 90167-4 . PMID 2847586 .
- ↑ M. Kirsch, EE Lomonosova, H.-G. Korth, R. Sustmann, H. de Groot: Hydrogen peroxide formation by reaction of peroxynitrite with HEPES and related tertiary amines. Implications for a general mechanism . In: J Biol Chem . 273, No. 21, 1998, pp. 12716-12724. doi : 10.1074 / jbc.273.21.12716 . PMID 9582295 .