Influence of Glycosylation on Interfacial Properties of Recombinant Mucins: Adsorption, Surface Forces, and Friction

Abstract

Interfacial properties of two brush-with-anchor mucins, C-P55 and C-PSLex, have been investigated at the aqueous solution/poly(methyl methacrylate) (PMMA) interface. Both are recombinant mucin-type fusion proteins, produced by fusing the glycosylated mucin part of P-selectin glycoprotein ligand-1 (PSLG-1) to the Fc part of a mouse immunoglobulin in two different cells. They are mainly expressed as dimers upon production. Analysis of the O-glycans shows that the C-PSLex mucin has the longer and more branched side chains, but C-P55 has slightly higher sialic acid content. The adsorption of the mucins to PMMA surfaces was studied by quartz crystal microbalance with dissipation. The sensed mass, including the adsorbed mucin and water trapped in the layer, was found to be similar for these two mucin layers. Atomic force microscopy with colloidal probe was employed to study surface and friction forces between mucin-coated PMMA surfaces. Purely repulsive forces of steric origin were observed between mucin layers on compression, whereas a small adhesion was detected between both mucin layers on decompression. This was attributed to chain entanglement. The friction force between C-PSLex-coated PMMA is lower than that between C-P55-coated PMMA at low loads, but vice versa at high loads. We discuss our results in terms of the differences in the glycosylation composition of these two mucins.

Synergies in lubrication

“…The lubricating ability of different types of mucins has been investigated on a range of different surfaces, 28,[53][54][55][56] and the lubrication performance reported is found to vary significantly depending on the mucin used and the nature of the substrate surface. In cases where anchoring is strong and the adsorbed amount is high, low friction forces are observed due to the presence of a high density of strongly hydrated oligosaccharide chains that counteract interpenetration and facilitate hydration lubrication.…”

“…53 It is generally acknowledged that it is the highly hydrated oligosaccharide side chains that facilitate lubrication between mucin layers, but only recently was it attempted to elucidate how the nature of the side-chains affects the lubrication performance between recombinant brush-with-anchor mucins. 56 It was found that the recombinant mucin with longer oligosaccharide side chains performed better at low loads, and this was interpreted as being due to higher hydration. However, at higher loads the reverse was observed and the mucin with shorter oligosaccharide side chains provided more efficient lubrication.…”

Probing the frictional properties of soft materials at the nanoscale

“…With the use of contact mechanics models, the probesample contact area could now be estimated and hence an absolute quantitative frictional force could be determined. At the same time, while measuring friction with commercial AFM tips is limited to the use of silicon or silicon nitride as a material with elastic modulus >10 GPa, colloidal probes offer a greater variety of choice regarding the material chemistry, 25,26 elastic modulus <10 GPa, 27,28 and probe radius of hundreds of nanometers to few micrometers (Fig. 2).…”

“…The left side of the figure illustrates FFM studies using a sharp tip, either silica, [58][59][60][61][62][63][64][65][66][67][68][69][70] or silicon nitride. 32,42,68, On the right side of the figure are shown the FFM studies using a colloidal probe made from: collagen; 96 latex; 97 polyethylene (PE); 25,28,45,98 polyethylene glycol (PEG); 99 poly(methyl methacrylate) PMMA; 26,27,95,100 polystyrene (PS); 33,71,101 cellulose; 31,[102][103][104][105][106][107][108][109] and silica. 35,36,98,[110][111][112][113][114][115][116][117] The volume of the symbol corresponds to the number of studies using the specific syste...…”

Formation of Protein Networks between Mucins: Molecular Dynamics Study Based on the Interaction Energy of the System

“…In this paper, MUC1 was chosen as an example of the mucin structure as it is most widely distributed in humans. There were several recent studies, theoretical [21][22][23], as well as experimental [24], which analyzed the docking/binding and adhesive properties of mucin, which suggest that hydrogen bonds, in particular inter-molecular interactions, play an important role in many biological processes. How mucins cross-link to form networks and which atomic interactions govern this process would seem to be of particular importance also for its frictional attributes.…”