A polydisperse linear random coil model for the quaternary structure of pig colonic mucin

The distribution of molecular weights for polymeric colonic mucus glycoprotein or ``mucin' isolated and solubilised in the presence of protease inhibitors from pig colons is shown to be considerably greater than its ``subunit' (thiol reduction product) and papain digested forms using the technique of size-exclusion chromatography coupled to multi-angle laser light scattering, and confirmed by sedimentation equilibrium measurements. The conformation of this mucin is probed by examining the molecular weight – intrinsic viscosity relationship in terms of the Mark-Houwink-Kuhn-Sakurada analysis for its polymeric (or ``whole'), reduced and papain-digested forms: an exponent ``a' of (1.1±0.1) is obtained indicating a linear random coil conformation consistent with other mucins. Size-exclusion chromatography coupled to multi-angle laser light scattering is shown to provide a relatively simple complementary technique to sedimentation equilibrium for the molecular weight distribution analysis of polydisperse materials. Received: 29 November 1996 / Accepted: 2 December 1996