BioWiki

Buffer solutions

Good's buffer

Good et al. 1)reported that the Zwitterionic buffers are suitable for biological experiments.

They have the following characters.

  • They have physiological range of pKa(6.0 - 9.0).
  • The pKa values of them are not influenced by temperature and concentration of them.
  • Chemically stable and biologically inert.
  • They can be used for culture of cells, and they does not penetrate cell membrane.
  • They does not disturb spectroscopic analysis.
namepKa(4℃)pKa (20℃)pKa(25℃)pKa(37℃)properties
MES6.336.156.105.97Autoclave with glucose causes decomposition.
ADA6.806.626.566.43This can chelate metal ions.
PIPES6.946.806.766.66This interferes Lowry analysis
MOPS7.417.207.146.98This is suitable for almost experiments.
HEPES7.777.557.487.3This is suitable for almost experiments except for Lowry analysis.
CHES9.739.559.509.36This buffers at basic pH (8.6 - 10.0). This has slight absorption at 260-280nm.

Phosphate buffer

See a Phosphate buffer page.

Other buffers

namepKa(4℃)pKa (20℃)pKa(25℃)pKa(37℃)properties
Tricine8.498.158.057.79Similar to Tris. This chelates metal ions.
Tris-HCl buffer8.758.308.087.82This is suitable for many experiments. But dependence on temperature is large. Besides, primary amine of this interferes Bradford assay, immobilization of proteins and so on.
Gly-Gly8.858.408.267.92Temperature dependent.

Titration curve

The following plot is a titration curve of Tris buffer. Notice that the pH change around pK is small.

#gnuplot
set xrange [0:1]\\ 
set xlabel "molecular ratio of Tris to acid"\\ 
set yrange [0:14]\\ 
set ylabel "pH"\\ 
set size 0.41\\ 
pK_Tris = 8.08\\ 
set label "pK = 8.08 (298K)" at 0.05,9\\ 
Tris(x) = pK_Tris+log(x/(1-x))\\ 
plot Tris(x),pK_Tris

References

  • Good NEet al.Biochemistry5p467-77(1966 Feb)
  • Good, N.E. & Izawana, S.: Methods Enzymol., Part B
    Vol. 24, p. 53 ff. (Pietro, ed.) (1972) Academic Press, New York
  • R.J. Beyon & J.S. Easterby: Buffer solutions The Basics,
    (C. Howe, ed.) 1 st ed. (1996) IRL Press, Oxford

Links

1)
Hydrogen ion buffers for biological research.
Good NE, Winget GD, Winter W, Connolly TN, Izawa S, Singh RM
Biochemistry5p467-77(1966 Feb)