Characteristics of H and L Subunits with Mass Spectrometry, Electrophoresis and Transmission Electron Microscopy in Liver Ferritin of Dasyatis Akajei

Liver ferritin of Dasyatis akajei (DALF) with mass spectrum purity was prepared in batches. Transmission electron microscopy (TEM) was used to determine the molecular sizes of DALF, protein shell, and iron core, respectively. SDS-PAGE analysis reveals that DALF consists of two different types of subunits, H and L subunits. Moreover, the two types of both H and L subunits and their homology were further identified by peptide mass fingerprinting. Redox reagents such as natural red, thionine, and methyl viologen and the acidity at pH 1.5 does not have abilities for weakening the interaction intensity of both H-L and L-L subunit polymers to form L subunit ions for mass spectrum (MS) analysis with MALDI-TOF MS, respectively. However, using a combined approach of both increasing the laser intensity and decreasing the matrix pH synchronously, an MALDI-TOF mass spectrometer can directly determine molecular weights of both H and L subunits in DALF, indicating that the interaction intensity both H-L and L-L subunit polymers is higher than that of H-H subunit type in DALF.