The expression of recombinant
allergens is becoming new insights of an important diagnosis and the
therapy of
allergies as well as molecular approaches to immunological and structural studies of
allergens.
Ovomucoid is a major food
allergens in the hen's egg white which causes immediate
food-hypersensitivity reactions mainly in children. A gene coding for the
cDNA representing an entire
ovomucoid molecule has been cloned in Escherichia coli under the control of T5 promoter fused with six-
Histidine tag at the amino terminal end. Upon induction, the E. coli cells, harbouring this construct, expressed the
recombinant protein as a soluble fraction and the recombinant
ovomucoid protein was purified to electrophoeretic homogeneity using Ni2+
nitrilotriacetic acid agarose affinity chromatography. Immunoblot analysis showed that human
IgE and
IgG binding activities of the recombinant
ovomucoid was identical to that of native analogue. The antigenicity and allergenicity of recombinant
ovomucoid were almost same as that of native form when tested with an ELISA using six individual patient's serum. CD spectra indicated that that the recombinant
ovomucoid has more alpha-helix and less beta-structure than native form. These results show that the recombinant
ovomucoid constructed in this study could be used for further studies on the immunological and structural studies of
ovomucoid.