Lactate dehydrogenase (LDH; EC 1.1.

Lactate dehydrogenase (LDH; EC 1.1.1.27) offers several
advantages over other possibilities as the enzyme of choice for a
student's first exposure to a purification scheme. These advantages
include its relative abundance in an easily obtainable
source, high specific activity, stability, ease of assay, wellunderstood
kinetics, and the availability of a good competitive
inhibitor. Also, when checking for purity using gel electrophoresis,
one tube can be stained with a general protein stain while a
second tube can be stained with a dye system specific for LDH to
show which protein band contains LDH.1 This can be compared
to an LDH control to identify the isozyme of LDH that was
purified.
The simple, inexpensive procedure reported here uses equipment
and materials normally found in biochemistry laboratories
and yet incorporates several important biochemical techniques
including spectrophotometry, chromatography, centrifugation,
and electrophoresis. The procedure presented is a modification
of one reported by Reeves. 2