EFFECT OF LONG-TIME STORAGE ON CYTOSOLIC GLUTATHIONE S-TRANSFERASES

Glutathione S-transferases are a family of enzymes catalyzing the conj ugation of glutathione to a wide variety of compounds. Stability of hu man liver cytosolic glutathione S-transferase enzyme activity and leve ls of glutathione S-transferase class Alpha and Mu were assessed. Cyto solic fractions of sixteen different patients were stored up to two ye ars at three different temperatures: -20 degrees, -80 degrees and -196 degrees Celsius. Samples were assayed for glutathione S-transferase e nzyme activity and glutathione S-transferase class Alpha and Mu levels , after 3, 6, 12 and 24 months of storage. No significant differences in glutathione S-transferase enzyme activity as well as in isoenzyme l evels were found during this 24 months of storage at the three differe nt temperatures. It is concluded that stability of glutathione S-trans ferases allows long term storage even at -20 degrees C, without signif icant loss of enzyme activity or enzyme protein.