FREEZE-THAW STUDIES OF A MODEL PROTEIN, LACTATE-DEHYDROGENASE, IN THEPRESENCE OF CRYOPROTECTANTS

The objective of this study was to investigate the behavior of lactate dehydrogenase (LDH) upon freezing and thawing, alone or in the presen ce of several selected cryoprotectants. Also, the influence of the fre ezing rate on retainment of LDH activity was investigated. It was obse rved that fast freezing caused less loss of LDH activity than slow fre ezing. The probable mechanisms of loss of activity after freeze-thaw c ycles were discussed. Selected cryoprotectants were evaluated for thei r ability to protect LDH during freeze-thaw cycles. Surface tension an d pH change measurements upon freezing of the cryoprotectant solutions were carried out. Based on the results of these experiments, a potent ial mechanism of cryoprotection has been developed.