Abstract:
The biophysical and biochemical properties of the erythrocruorin from the New Zealand native earthworm Maoridrilus montanus have been studied. In gel filtration four components A, B, C and D representing 2%, 5%, 90% and 3% respectively of the total material at pH 7.0 are evident.
(i) Fraction C
This component has a molecular weight of 3.2 x 10 6 dalton at pH 7.0 by gel filtration. Under the electron microscope it appears to be composed of 12 subunits arranged in 2 superimposed hexagonal rings. The absorption spectrum and N-terminal groups are reported. The haem and iron contents of the molecules are 2.78% and 0.219% respectively.
Gel filtration at pH 9.0 shows that the molecule dissociates into subunits with molecular weights of 230,000 and 130,000 for peaks c and d, and 1.9 x 10 6 and 1.1 x 10 6 daltons for peaks a and b respectively.
Gel filtration at pH 11 shows that the molecule dissociates into subunits with Mr of 160,000, 100,000 and 45,000 corresponding to peaks A, B and C respectively. In the presence of SDS-2-mercaptoethanol the protein dissociates into 9 bands with Mr ranging from 12,380 → 100,000. In the presence of SDS only 5 subunits are observed ranging from Mr of 13,180 → 81,200. Alkaline electrophoresis experiments were also carried out on the protein revealing 2 subunits at pH 9 and 1 subunit after dissociation at pH 11.
