The physicochemical characterisation of pepsin degraded pig gastric mucin

Compositional analysis showed that this mucin contains protein (15%), carbohydrates (55%) of which the constituents are: fucose (4%), galactose (9%), glucosamine (55%), glucosamine (33%) and sialic acid (2%). The latter component gives the mucin polymer a pH-dependant negative charge, with a ζ-potential of −3 mV at pH 1.2 up to −11 mV at pH 7.4. The weight average molar mass was ∼1 × 106 g/mol and intrinsic viscosity was ∼0.42 dL/g although there was a small pH dependency due to the polyelectrolyte behavior of the polymer. The measurements of viscosity versus shear rate showed shear thinning behavior and the critical overlap concentration was determined to be 10-11% w/v indicating a compact structure. Knowledge of these properties is fundamental to the understanding interactions of mucins, with for example, novel drug delivery systems.