Use of purified lyophilized human lactate dehydrogenase isoenzyme 5 in a study of measuring lactate dehydrogenase activity.
We examined the stability of human lactate dehydrogenase (EC 1.1.1.27) isoenzyme 5--purified to a specific activity of about 400 kU/g--when lyophilized in a buffered, stabilized matrix of bovine albumin. This isoenzyme was prepared with a final activity of about 500 U/L and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. This isoenzyme decayed with approximate first-order kinetics, with an estimated half-life at -20 degrees C of about 475 years. Stability of reconstituted samples stored at 20 or 4 degrees C was poor, suggesting that the reconstituted material should be used without delay; material stored at -20 degrees C showed excellent stability for 15 days. We propose that such preparations might be further investigated as standards for use in electrophoresis of lactate dehydrogenase isoenzymes.
Department of Clinical Biochemistry, University Hospital, London, Ontario, Canada.
D A
DA
Smith
G C
GC
Moses
A R
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Henderson
D004795:Enzyme Stability; D005612:Freeze Drying; D006801:Humans; D007525:Isoelectric Focusing; D007527:Isoenzymes; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000032:analysis* / Q000302:isolation & purification*; D012015:Reference Standards
D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase