Abstract
Purpose: :
To assess comparatively the influence of composition and capacity for fibrillar interactions of collagen IV on the structure of the basement membrane of the lens capsule through the generation of in silico collagen IV networks utilizing a coarse-grained Monte Carlo approach.
Methods: :
Model collagen IV networks based on the basement membrane of the lens capsule were generated employing a Monte Carlo algorithm. The effect of composition of 1(IV)1(IV)2(IV) and 3(IV)4(IV)5(IV) collagen protomers was explored via two possible consequences of the greater cysteine content (and thus greater capacity for disulfide bonding) of the 3(IV)4(IV)5(IV) trimer. Intrafibrillar interactions were modeled by increasing fiber stiffness, and interfibrillar interactions were modeled by increasing the interaction energy of the 7S domains of the collagen protomers. The structure and heterogeneity of the networks were quantified through moments of the spatial distribution, lattice correlation (Fourier transform of fiber density), and void size.
Results: :
In all simulations, segregation between the 1(IV)1(IV)2(IV) and 3(IV) 4(IV)5(IV) networks were observed in varying degrees. The segregation was quantified via increasing second central moment of fiber location and the lattice correlation function. Additionally, the standard deviation in void size increased as larger voids dominated the mean void size. Varying results were observed by manipulating concentrations and relative energetics of inter- and intrafibrillar interactions.
Conclusions: :
Differences between either inter- and intrafibrillar interactions in the major and minor protomers of the basement membrane have a significant influence the morphology of simulated collagen IV networks. Such effects become pronounced as the concentration of the minor protomer becomes large.
Keywords: protein structure/function