The purpose of this study is to further verify the mechanism of transglutaminase (TGase) cross-linking soybean protein isolate (SPI). The mechanism of SPI cross-linked with transglutaminase is simulated by Gaussian software

which is usually used in the field of the heterogeneous catalysis and biocatalysts. And the catalytic process is simulated by the chemical method. The results show that the center of transglutaminase activity comnected with 5 amino acids is the optimal structure by calculation. The enzymatic catalysis of the lysine and glutamine dehydrogenation reactions is simulated. The calculating results indicate that there are 8 possible deamination reactions. However

only 2 reactions can be carried out smoothly. Each method has a certain proportion

that is

glutamine amide γ-amide and lysine ε-amino hydrogen. Deamination reaction occurred between amino group and lysine toxic amino hydrogen

and the energy barriers of the reaction process were 49.50 and 44.35 kcal/mol

respectively. SPI can be cross-linked randomly to produce high molecular weight polymers. As a result

the functional characteristics of SPI is changed

and the gel strength of isolated soybean protein is improved.