Abstract
Experiments were conducted to confirm the importance of the hydrophobic chain length (n) of synthetic mono-tailed glycolipids for maintaining the enzymatic activity of a model protein, lactate dehydrogenase (LDH), during the freeze/thaw process. At low concentrations, mono-tailed glycolipids maintained the enzymatic activity of LDH solution after the freeze/thaw process. Above the threshold, the maintenance effect increased with an increase in n of the n-alkyl glucoside (n = 4, 6, and 8) in the presence of 0.001 to 1.0 mg ml^<-1> glycolipid concentrations, while 6-O-alkanoyl trehalose (n = 8 and 10) exhibited a similar tendency as n-alkyl glucosides. 6-O-myristoyl trehalose (n = 14) was an exception, possibly because of phase separation at subzero temperatures. When the slope of the logarithmical concentration vs. relative activity curve was calculated above the threshold concentration, a linear relationship was observed between the slope and n. This finding demonstrates the importance of designing an appropriate n for glycolipid protectants to effectively maintain enzymatic activity during the freeze/thaw process. In addition, structural dependence of the threshold on the sugar moiety was suggested.
