Biochemical characterization of recombinant Phl p 6 and comparison with natural Phl p 6 and recombinant Phl p 5

House dust mites and grass pollens are the most important allergen sources worldwide. Here, we report the characterization of recombinant Phl p 6, a major grass pollen allergen from Phleum pratense, using standard biochemical methods. Recombinant Phl p 6 was expressed in Pichia pastoris and recombinant Phl p 5.0107, was expressed in E.coli. Both were purified to homogeneity and analyzed by SDS-PAGE. rPhl p 6 and nPhl p 6 were analyzed by immunoblotting and rocket immuno electrophoresis (RIE). Melting temperatures of rPhl p 6, nPhl p 6 and rPhl p 5 were determined by Circular Dichroism (CD). Recombinant Phl p 6 migrated in reduced silver stained SDS-PAGE and immunoblots as nPhlp6. When analyzed by RIE rPhl p 6 and nPhl p 6 formed precipitates of similar morphology. Furthermore, rPhlp6, nPhlp6 and rPhl p 5 gave rise to similar spectra (local max at 192 nm and local min at 208 and 222 nm) when analyzed by CD. CD temperature denaturation analysies showed similar melting temperatures, 58.5 ± 0.5°C (mean ± 95% CL) (rPhl p 6) and 59.0 ± 0.3°C (nPhl p 6) and 65.3 ± 1.4°C (rPhlp 5), respectively. An expression and purification procedure has been established enabling the production of recombinant Phl p 6 having biochemical characteristics and immunochemical activity corresponding to that of the natural allergen from grass pollen.