Molecular weight distribution analysis by ultracentrifugation: Adaptation of a new approach for mucins

Mucins are the key macromolecular component of mucus, natureʹs natural lubricant, and one of the most important physical properties is their molecular weight distribution. A new approach for polydisperse polymers was recently published based on sedimentation velocity in the analytical ultracentrifuge and converts a distribution of sedimentation coefficient g(s) vs. s plot into a distribution of molecular weight utilising the power-law or scaling relationship between the sedimentation coefficient and molecular weight, s = κ s   M w b where s is the sedimentation coefficient, Mw is the weight average molecular weight and κs and b are characteristic coefficients related to conformation. We investigate the possibility of using a large database of previously published values of s an M to define κs and b for both aqueous solution and aqueous solution supplemented by 6 M guanidine hydrochloride (a solvent which helps to minimise sample degradation). These values are then applied to a study of the molecular weight distributions of preparations of human gastric mucin in the different solvents and at different stages of purification.