Physical And Chemical Characteristics Of Four Pancreas Ferritins

Thermal denaturation method, ultrafiltration method and DEAE-cellulose chromatography were used to separate and purify four pancreas ferritins, named PPF (Pig Pancreas Ferritin), SPF( Scalper Pancreas Ferritin), DPF(Duck Pancreas Ferritin) and CPF (Chicken Pancreas Ferritin), respectively. The methods mentioned above and PAGE combined further to prepare a small batch of ferritin with the level of mass spectrometry for analysis on the protein composition and structure.These pancreas ferritins showed different mobilities in PAGE gel which gradation was V_PPF>V_SPF>V_DPF>V_CPF, and the results meaned that their molecular weights gradation was CPF_mw>DPF_mw>SPF_mw>PPF_mw. Moreover, the molecular weights of the four ferritins were larger than that of horse spleen ferritin (HSF). SDS-PAGE results showed that CPF, DPF, SPF and PPF consisted of H and L subunits, but with different H/L ratios. And then the two subunit types of four ferritins were identified by peptide-mass fingerprinting (PMF) technology. The ferritins, such as CPF, DPF, SPF and PPF, treated with SDS showed the band numbers of the protein ranging from 3 to 6 with different pI values respectively in IEF gel. This phenomenon revealed that the intensities of complicated interactions between H and L subunits were very different and that the different polymers existed in ferritins. The heterogeneity might response to iron release of ferritin, requirement of animals to iron and iron detoxification vivo conjecturally.Three main characteristics were summarized followed: (1) An approximately 1:2 ratio of H to L subunits was observed in PPF, indicating three combined types of L-L, L-H and H-H; (2) In terms of kinetics, the law of the iron releasing speed from PPF was similar to that of PSF and HSF;(3) The character of PPF subunits' structure differed from those of other mammalian ferritins, suggesting that this peculiar subunits structure was correlative with the exceptional iron release and storage.The rule of apoPPF trapping Zn²⁺ was studied for establishing the calculation formula under the conditions of different pH and reactive time, respectively. These experimental results could be the foundation for forming a nanometer cisplatin core-ferritin as new carrier of anticancer drugs.