Fabrication of the ferritin-mannoprotein shell-core heteroprotein complex for stabilization of bioactive molecules

Ferritin has a cage-like structure with an 8-nm cavity and is capable of encapsulating bioactive molecules. Mannoprotein is a highly glycosylated protein with a N-glycosylated or O-glycosylated structure. These two proteins can potentially form heteroprotein complexes due to their different characters. The aim of this study was to prepare mannoprotein-ferritin heteroprotein shell-core complexes (MFH), to investigate the interaction between ferritin and mannoprotein, and to assess the binding behavior, structure, stability, and protection of MFH on EGCG molecules. ζ-potential measurements showed that the formation of MFH was mainly driven by the electrostatic interactions between two proteins with opposite charges. The self-assembly of ferritin was further utilized to prepare EGCG-encapsulated mannoprotein-ferritin heteroprotein complexes (EMFH), with an encapsulation rate of 18.8% (w/w). The EMFH showed an aggregation in a regular spherical morphology and led to an increase in its size, with a primary RH of about 257.2 ± 5.8 nm. In addition, compared to the EGCG-encapsulated ferritin (EF), EMFH enhanced the thermal and photostability of EGCG and facilitated the controlled release of EGCG during simulated gastrointestinal digestion. This study expands the application of heteroprotein complexes based on the cage-like ferritin and mannoproteins in stabilizing bioactive compounds.