# A Coarse-Grained MARTINI Model for Mucins

## TL;DR

Researchers developed a new model to simulate mucins, which are important proteins in mucus, making it easier to study their structure and function.

## Contribution

A new coarse-grained model for mucins was developed and validated using the MARTINI 3 framework.

## Key findings

- The MARTINI 3 model accurately reproduces the structural properties of MUC5B observed in atomistic simulations.
- The model captures the bottlebrush structure of MUC5B and the power-law scaling of radius of gyration with molecular weight.
- The model enables efficient simulations of mucins and glycoproteins for applications in food science, drug delivery, and biomaterials.

## Abstract

Highly glycosylated proteins known as mucins are the
principal
components of mucus, the gel-like secretion that protects and lubricates
many tissues in the human body. Molecular dynamics (MD) simulations
are a useful tool to investigate the nanoscale structure and function
of proteins; however, the high molecular weight of mucins makes them
a challenging target for atomistic MD simulations. To enable long-time
MD simulations of large mucins, we develop and validate new coarse-grained
force field parameters within the MARTINI 3 framework for the glycosylated
domains of salivary mucin, MUC5B. We use atomistic MD simulations
of segments of the protein backbone connected to O-glycans with the CHARMM36m force field to parameterize the bonded
parameters. The structural properties of MUC5B from the MD simulations
with MARTINI 3, including the radius of gyration, end-to-end distance,
and solvent accessible surface area, agree well with the atomistic
simulations. Our MARTINI 3 parameters reproduce the bottlebrush structure
of MUC5B observed in atomistic MD simulations and previous experiments.
The power-law scaling of the radius of gyration with molecular weight
is within the range observed in previous experiments of mucins. Accordingly,
the MARTINI 3 parameters developed and validated in this study will
facilitate accurate and efficient MD simulations of mucins and other
glycoproteins for a variety of application areas including food science,
drug delivery, and biomaterials.