Purification and properties of mycoferritin from Mortierella alpina

Abstract

A culture of Mortierella alpina Peyroud isolated from soil and grown on Czapek-Dox medium was found to contain a high concentration of mycoferritin (MF). The MF was extracted from lyophilized mycelium by grinding with 0.1 M, pH 7.0, potassium-phosphate buffer and chloroform followed by differential centrifugation. Sucrose density-gradient centrifugation of the concentrated MF resulted in a brownish-yellow band in the region of 60–70 S. Following dialysis and concentration by high-speed centrifugation, the MF was compared to horse-spleen ferritin (HF). The ultraviolet (uv.) and infrared (i.r.) spectra of MF and HF were identical. Negatively stained preparations examined in the electron microscope showed particles of about 10 nm diameter. Sedimentation rates of S20,w = 66 for MF and S20,w = 56 for HF were obtained by analytical ultracentrifugation. The MF preparation contained 83% protein and 17% iron. The molecular weight of the protein subunit was determined by gel electrophoresis to be about 19 300 daltons.