Abstract:

Electrophoresis-purity lactate dehydrogenase (LDH) from duck liver was obtained through the procedures of
homogenization, buffer solution extraction, ethanol precipitation, ammonium sulfate fractionation, DEAE-Sepharose ion
exchange chromatography and Superdex-200 gel ?ltration chromatography. An activity recovery of 25.79% was obtained.
The specific activity of the purified enzyme was 668.82 U/mg with a purification fold of 185.78. The total molecular mass
of the LDH was 170.93 kD consisting of a 44.72 kD subunit. The optimum temperature and pH for the LDH was 45 ℃
and 7.4, respectively. It was stable in the ranges of pH 5–10 and 25–45 ℃. Its Km was 3.407 μmol/L towards NADH and
8.431 μmol/L towards sodium pyruvate. The enzyme activity was be strongly inhibited by SDS, oxalic acid, Cu2+ and Ag+,
but could be enhanced by low concentration of Co2+ and K+.

Key words: duck liver, lactate dehydrogenase, isolation and puri?cation, characterization