Recombinant Expression and Allergenicity Analysis of Arginine Kinase from Scylla paramamosain

To compare the allergenicity of native arginine kinase (nAK) and recombinant AK (rAK) from Scylla paramamosain and to identify the predominant allergenic domain of AK, AK was divided into 4 fragments: AK-E1 (amino acid (AA) 1–92), AK-E2 (AA 87–187), AK-E3 (AA 172–265), and AK-E4 (AA 276–357) based on the distribution of epitopes and the spatial structure of the AK molecule. The four recombinant fragments were expressed in the prokaryotic system Escherichia coli, and then nAK, rAK, and the recombinant fragments were purified. The allergenicity of recombinant proteins were evaluated using BALB/c mice. The results showed that the levels of specific antibodies in the serum and the secretion of Th2 type cytokines by the splenocytes of mice sensitized with rAK significantly increased, but the immunogenicity of rAK was weaker than that of nAK. Among the 4 fragments of AK, AK-E2 had the strongest immunogenicity. Meanwhile, rAK could stimulate RBL-2H3 cells to release β-hexokinase, but it was less effective than nAK. Among the 4 expressed fragments, AK-E2 and AK-E4 had a stronger stimulating effect on effector cells. In conclusion, the rAK expressed in the prokaryotic system showed weaker immunogenicity than nAK, and among the 4 fragments of AK, AA 87–187 has the strongest immunogenicity while AA 276–357 has the strongest immunoreactivity.