Sk. Basak et Mr. Ladisch, CORRELATION OF ELECTROPHORETIC MOBILITIES OF PROTEINS AND PEPTIDES WITH THEIR PHYSICOCHEMICAL PROPERTIES, Analytical biochemistry, 226(1), 1995, pp. 51-58
Electrophoretic mobilities, mu, of nine proteins (M(r) 14,200 to 70,00
0) in 28 mM Tris/47 mM glycine buffer at pH 8.77 and 5 mM ionic streng
th were measured by laser Doppler velocimetry and correlated to ratios
of charge (q) to molecular weight (M(r)) and shape factor (f/f(0)) by
the equation mu(f/f(0)) = (Aq/M(r)(p) - B). This correlation was prev
iously reported for peptides and proteins for mu measured at 100 mM io
nic strength. When A = 6.048 X 10(-3), B = 1.13 X 10(-5), and p = 2/3,
the correlation fitted 51 measured and literature values over the mol
ecular weight range of 178 to 140,000 for components whose electrophor
etic mobilities ranged from +13.35 X 10(-5) to -19.7 X 10(-5) cm(2)/(V
.s). The experimental measurements confirm the general suitability of
p = 2/3 and show that the familiar charge/mass relation for electropho
resis is applicable to proteins in low-ionic-strength buffers which ar
e typic al of electrochromatography systems. Extrapolation of the corr
elation to different ionic strengths indicates that a low-ionic-streng
th buffer amplifies differences of electrophoretic mobility as a funct
ion of charge/mass, while high ionic strength diminishes such differen
ces. (C) 1995 Academic Press, Inc.