Rapid and Efficient Purification of Haemolymph Ferritin from Cricket, Gryllus bimaculatus

ABSTRACT The Gryllus bimaculatus ferritin was purified from the haemolymph by a consecutive four‐step procedures consisting of 50% ammonium sulfate fractionation, anion exchange column chromatography using HiTrapTM Q column (1.6 x 4 cm, Amersham Bioscience), 70°C heat treatment for 10 min, acid treatment of 0.1 M sodium acetate buffer (pH 6.0), and gel filtration column chromatography using G4000SW column (0.75 x 60 cm, Tosoh, Japan) connected on FPLC system. The purified ferritin was found to have two major subunits of 32 and 30 kDa and three minor subunits of 28, 27, and 25 kDa by 2D electrophoresis analysis. Amino acid composition analysis showed that there are high contents of Asp, Glu, Met, Leu, and Lys residues in ferritin while low contents of Cys, Tyr, and Trp residues in the protein. G. bimaculatus haemolymph ferritin could be classified as a methionine‐rich protein.