Use of purified lyophilized human lactate dehydrogenase isoenzymes in a study of the measurement of lactate dehydrogenase activity.
We examined the stability of human lactate dehydrogenase (EC 1.1.1.27; LD) isoenzymes 1, 2, and 3--purified to specific activities of about 200 kU/g--when lyophilized in a buffered stabilized matrix of bovine albumin. Each isoenzyme was prepared at two activity concentrations and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. LD-1 activity decayed with zero-order kinetics, LD-2 and LD-3 with first-order kinetics. The extrapolated half-lives of these preparations at -20 degrees C varied between 80 and 530 years. Stability of reconstituted samples stored at 4 degrees C was excellent for LD-1 but poor for LD-2 and LD-3. We suggest that preparations of human LD-1 be further investigated as a possible reference material.
Smith
D A
DA
Moses
G C
GC
Henderson
A R
AR
D005612:Freeze Drying; D006801:Humans; D007527:Isoenzymes; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000302:isolation & purification*; D013048:Specimen Handling / Q000379:methods; D013696:Temperature; D013997:Time Factors
D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase