title: Effect of hydration on structural and thermodynamic properties of pig gastric and bovine submaxillary gland mucins.
abstract: One of the essential functions of mucous gel is protection of tissues against dehydration. The effect of hydration on the structural and thermodynamic properties of pig gastric mucin (PGM) and bovine submaxillary gland mucin (BSM) have been studied using atomic force microscopy (AFM), sorption, and differential scanning calorimetry (DSC). The analysis of sorption isotherms shows the higher water sorption capacity of PGM compared to BSM at RH levels lower than about 78%. The value of the hydration enthalpy at zero water content at 25 °C for both biopolymers is about -20 kJ/mol. Glass transitions of BSM and PGM occur at RH levels between 60 and 70% for both mucins. AFM indicates the presence of a dumbbell structure as well as a fiber-like structure in PGM samples. The experimental volume of the dry dumbbell molecule obtained by AFM is 3140 ± 340 nm(3). Using DSC data, the amount of nonfreezing water was calculated to be about 0.51 g/g of PGM. The phase diagram of PGM demonstrates two regions of different Tg: dependent and independent of hydration levels. In particular, at mucin concentrations from 0 to 67 wt %, the glass transition occurs at a constant temperature of about -15 °C. At higher concentrations of mucin, Tg is increasing with increasing mucin concentrations.
authors.affiliation: Biomedical Science, Faculty of Health and Society, Malmö University , SE-205 06 Malmö, Sweden.
authors.forename: Yana
authors.initials: Y
authors.lastname: Znamenskaya
authors.forename: Javier
authors.initials: J
authors.lastname: Sotres
authors.forename: Johan
authors.initials: J
authors.lastname: Engblom
authors.forename: Thomas
authors.initials: T
authors.lastname: Arnebrant
authors.forename: Vitaly
authors.initials: V
authors.lastname: Kocherbitov
mesh_terms: D000818:Animals; D002151:Calorimetry; D002417:Cattle; D018625:Microscopy, Atomic Force; D009077:Mucins / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D013363:Submandibular Gland / Q000737:chemistry* / Q000378:metabolism; D013552:Swine; D013816:Thermodynamics; D014867:Water / Q000737:chemistry / Q000378:metabolism
chemical_list: D009077:Mucins; D014867:Water