Good* Buffer Properties

Physical properties of the Good buffers. The maximum distance between atomic centers was measured from a 3-D model of the molecule and used as an estimate of the Stokes radius (a) of the molecule. The same was done for weak electrolytes with known diffusion coeficients (D). Linear regression of D vs 1/a for the weak electrolytes was used to predict the unknown Ds (E[D]) of the Good buffers.

Buffer	Mr	pKa	atomicdist	2a [Angstroms]	E [D]
MES	195.23	6.15	O7-H20	7.08	0.820
ACES	182.19	6.90	H12-H13	10.03	0.668
MOPS	209.26	7.15	H14-H21	10.15	0.664
HEPES	238.30	7.55	O14-H16	11.41	0.618
TRICINE	179.17	8.15	H13-H16	8.56	0.731
TRIS	121.14	8.30	H11-H15	6.28	0.886

*

Good, N. E., and Izawa, S. (1972). Hydrogen ion buffers. Methods Enzymol 24, 53-68.

Ferguson, W. J., Braunschweiger, K. I., Braunschweiger, W. R., Smith, J. R., McCormick, J. J., Wasmann, C. C., Jarvis, N. P., Bell, D. H., and Good, N. E. (1980). Hydrogen ion buffers for biological research. Anal Biochem 104, 300-10.

Last Updated on 05/13/2000
By Joseph G. Kunkel
Email: joe@bio.umass.edu