ferritin protein is involved in biological tissues in the storage and management of iron -an essential micro-nutrient in the majority of living systems. While there are extensive studies on iron-loaded ferritin, its functionality in iron delivery is not completely clear. Here, for the first time, differential pulse voltammetry (DpV) has been successfully adapted to address the challenge of resolving a cascade of fast and co-occurring redox steps in enzymatic systems such as ferritin. Using DpV, comparative analysis of ferritins from two evolutionary-distant organisms has allowed us to propose a stepwise resolution for the complex mix of concurrent redox steps that is inherent to ferritins and to fine-tune the structure-function relationship of each redox step. indeed, the cyclic conversion between fe 3+ and fe 2+ as well as the different oxidative steps of the various ferroxidase centers already known in ferritins were successfully discriminated, bringing new evidence that both the 3-fold and 4-fold channels can be functional in ferritin.Ferritin is an ubiquitous protein 1,2 involved in the storage and management of iron -an essential micro-nutrient for almost all living systems. The protein occurs in abundance in the cytosol and mitochondria, where it helps maintaining the performance of critical biochemical reactions 3-6 and balance oxidative stress processes 7 . Ferritin is therefore mainly internal in most systems, but can sometimes be a secreted enzyme 7 , and can thus be used to manage balance of iron both intra-and extracellularly, which can protect from deleterious excess of iron uptake, but also from viral and bacterial infections. Ferritin is known to take up iron (as Fe 2+ ) and store it in stable unreactive Fe 3+ -oxide/hydroxide form (primarily ferrihydrite). It is believed to deliver Fe back in a functional Fe 2+ form, where and when needed for biological processes 8 . In spite of many biochemical studies on performance of loaded ferritin, some parts of the molecular mechanisms of iron uptake, e.g., associated with oxidation steps, and most of the iron release and delivery, e.g., associated with reduction steps), remain largely unclear and speculative [8][9][10][11] .Structurally, ferritin is a biomacropolymeric enzyme constituted of 24 subunits (Fig. 1a,b) forming a hollow structure -often referred to as a cage that can be loaded 12 with Fe. The cage has an octahedral (432) symmetry where the 4-fold and 3-fold axes of symmetry are the place where 4 and 3 subunits meet together to respectively delineate six four-fold channels and eight three-fold channels. These channels have a small diameter (ranging from ~0.2 nm to ~0.5 nm) that varies along the 3 -4 nm length of the channels. To date both the 3-fold and 4-fold channels have been considered for the Fe 2+ ion entry into the core of the cage, but proof of natural activity 8,11,13 has been delivered only for the 3-fold channels. There are three types of ferritin subunits: Light (L), a Middle (M) and a Heavy (H) subunit, in increasing order of molecul...