Comparison of deamidation activity of transglutaminases

A comparison was made of the deamidation activity of transglutaminases from guinea pig liver (GTGase), fish red sea bream liver (FTGase) and microorga nisms (MTGase). Against the Z-Gln-Gly, kinetic constants of the deamidation and incorporation of primary amine were measured. GTGase and FTGase showed similar deamidation activity, however, that of MTGase was less than 1/7 of the other two TGases, Against the proteins, N,N-dimethylated casein and na tive gliadin, FTGase was the most active and deamidated respectively 45.5% and 38.2% of Gln residues. The deamidation rate of these proteins by GTGase was less than 1/2 and these results were expected to be caused by the diff erence of substrate specificity of the TGases.