Numerical Study on the Relationship between the Number of Ferritin Subunits and the Size of Outer Diameter

Ferritin is assembled from sub-chains into a spherical shape. We have found that the number of sub-chains is generally 3, 6, 8, 12, 24, 36, and the corresponding spherical volume (outer diameter) is also different. In this paper, using the protein structural data from PDB website, linear regression was carried out to model the relationship between sub-chain number and outer diameter of 25 ferritins by calculation and analysis, but the results were not ideal. In order to improve the model, we divided the 25 proteins into two groups by molecular evolution, followed by the establishment of a linear model. The correlation coefficient of one group was R2 = 0.98. Based on calculations and modelling, we hypothesize that the new ferritin formed by the 3kx9 site-directed mutagenesis is no longer 24-chain, but a 36-chain mutant.