2020 Charged glycan residues critically contribute to the adsorption and lubricity of mucins

Authors:
Matthias Marczynski^a, Bizan N.Balzer^bc*, Kun Jiang^d,Theresa M.Lutz^a, Thomas Crouzier^d, Oliver Lieleg^a

Journal:
Colloids and Surfaces B: Biointerfaces, Vol. 187, 03 2020, 110614 ; DOI: 10.1016/j.colsurfb.2019.110614

Institut:

^a Department of Mechanical Engineering and Munich School of Bioengineering, Technical University of Munich, Boltzmannstr. 11, 85748, Garching, Germany

^b Department of Chemistry and Pharmacy, Institute of Physical Chemistry, Albert-Ludwigs-University Freiburg, Albertstr. 23a, 79104, Freiburg, Germany

^c Cluster of Excellence livMatS@FIT, Freiburg Center for Interactive Materials and Bioinspired Technologies, Albrecht-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110, Freiburg, Germany

^d Division of Glycoscience, School of Biotechnology, Royal Institute of Technology, Albanova University Center, 10691, Stockholm, Sweden

Abstract:

In the human body, mucin glycoproteins efficiently reduce friction between tissues and thereby protect the mucosa from mechanical damage. Mucin lubricity is closely related to their molecular structure: it has been demonstrated previously that the hydrophobic termini of mucins critically contribute to their lubricity. If and how intrinsic sources of negative charge in mucins, e.g., sulfated glycans and sialic acid residues, are relevant for the tribological behavior of mucin solutions has, however, not been addressed yet. In this manuscript, we show that the removal of either sialic acid or sulfate groups, which comprise only a minor amount of the total molecular weight, from MUC5B drastically reduces its lubricity. For MUC5AC solutions, however, this effect only occurs once mucin-associated DNA is removed as well. We find that neither the hydration state nor the average conformation of mucins adsorbed onto hydrophilic or hydrophobic surfaces is affected by the removal of anionic sugars. Instead, our data suggests that a loss of anionic sugars mainly influences the dynamic adsorption process of mucins onto both hydrophilic and hydrophobic surfaces.