@article {Gniewek2012a, title = {Coarse-grained modeling of mucus barrier properties}, journal = {Biophysical Journal}, volume = {102}, number = {2}, year = {2012}, month = {jan}, pages = {195{\textendash}200}, abstract = {

We designed a simple coarse-grained model of the glycocalyx layer, or adhesive mucus layer (AML), covered by mucus gel (luminal mucus layer) using a polymer lattice model and stochastic sampling (replica exchange Monte Carlo) for canonical ensemble simulations. We assumed that mucin MUC16 is responsible for the structural properties of the AML. Other mucins that are much smaller in size and less relevant for layer structure formation were not included. We further assumed that the system was in quasi-equilibrium. For systems with surface coverage and concentrations of model mucins mimicking physiological conditions, we determined the equilibrium distribution of inert nanoparticles within the mucus layers using an efficient replica exchange Monte Carlo sampling procedure. The results show that the two mucus layers penetrate each other only marginally, and the bilayer imposes a strong barrier for nanoparticles, with the AML layer playing a crucial role in the mucus barrier.

}, keywords = {Adhesives, Adhesives: chemistry, Adhesives: metabolism, Glycocalyx, Glycocalyx: chemistry, Glycocalyx: metabolism, Models, Molecular, Mucins, Mucins: chemistry, Mucins: metabolism, Mucus, Mucus: chemistry, Mucus: cytology, Mucus: metabolism, Nanoparticles, Nanoparticles: chemistry, Protein Conformation, Surface Properties}, issn = {1542-0086}, doi = {10.1016/j.bpj.2011.11.4010}, url = {http://www.ncbi.nlm.nih.gov/pubmed/22339855}, author = {Pawel Gniewek and Andrzej Koli{\'n}ski} } @article {Gniewek2010, title = {Coarse-grained Monte Carlo simulations of mucus: structure, dynamics, and thermodynamics}, journal = {Biophysical Journal}, volume = {99}, number = {11}, year = {2010}, month = {dec}, pages = {3507{\textendash}16}, publisher = {Biophysical Society}, abstract = {A simple coarse-grained model of mucus structure and dynamics is proposed and evaluated. The model is based on simple cubic, face-centered lattice representation. Mucins are simulated as lattice chains in which each bead of the model chains represents a mucin domain, equivalent to its Kuhn segment. The remaining lattice sites are considered to be occupied by the solvent. Model mucins consist of three types of domains: polar (glycosylated central segments), hydrophobic, and cysteine-rich, located at the terminal part of the mucin chains. The sequence of these domains mimics the sequence of real mucins. Static and dynamic properties of the system were studied by means of Monte Carlo dynamics. It was shown that the model system undergoes sol-gel transition and that the interactions between hydrophobic domains are responsible for the transition and characteristic properties of the dynamic network in the gel phase. Cysteine-rich domains are essential for frictional properties of the system. Structural and dynamic properties of the model mucus observed in simulations are in qualitative agreement with known experimental facts and provide mechanistic explanation of complex properties of real mucus.}, keywords = {Cysteine, Cysteine: chemistry, Diffusion, Gels, Humans, Hydrophobic and Hydrophilic Interactions, Molecular Dynamics Simulation, Monte Carlo Method, Mucins, Mucins: chemistry, Mucus, Mucus: chemistry, Protein Structure, Tertiary, Thermodynamics}, issn = {1542-0086}, doi = {10.1016/j.bpj.2010.09.047}, url = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2998598\&tool=pmcentrez\&rendertype=abstract}, author = {Pawel Gniewek and Andrzej Koli{\'n}ski} }