Hoefer HE-PLUS System - Manual (Page 11)

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Operating Instructions
A. Guidelines for Selecting Electrophoresis
Buffers and Gel Concentrations
The two most commonly used buffers for hori-
zontal electrophoresis of double stranded DNA
in agarose gels are Tris-Acetate-EDTA (TAE)
and Tris-Borate-EDTA (TBE). While the resolv-
ing powers of these buffers are very similar,
the relative buffer capacities are very different,
conferring different run attributes which are
summarized below:
TAE
Tris-acetate has traditionally been the more
commonly used buffer. However, its relatively low
buffer capacity will become exhausted during
extended electrophoresis, making buffer recirculation
necessary in runs exceeding 140 mA-hours. Potential
advantages of using TAE buffer over TBE buffer
include superior resolution of supercoiled DNA
and approximately 10% faster migration of double-
stranded linear DNA fragments.
TBE
Tris-borate’s significantly greater buffering capacity
and its relatively low current draw eliminates the
need for recirculation in all but the most extended
runs ( > 300 mA-hours). TBE buffer systems are not
recommended when fragments are to be recovered
from the gel after electrophoresis.