Abstract
Some molecular properties of αs1-κ-casein complex, αs1- and κ-casein polymers were examined by gel filtration, ultracentrifugation, and viscometry at pH 7.1. The Stoke's radii of αs1-κ-casein complex, αs1- κ- and casein polymers were 99, 44 and 108 Å, respectively. The molecular weight of the above proteins were approximately 45×104, 10×104 and 80×104, respectively. The stokes radius of αs1-κ-casein complex reduced compared with that of casein polymer and the molecular weight of the complex was about half that of κ-casein polymer. These results suggest that αs1-casein polymer dissociates into 4 smaller particles when αs1-κ-casein complex is formed. The frictional coefficient and Scheraga-Mandelkern constants for each protein suggest that the molecular shape of αs1-casein polymer is globular and that of αs1-κ-casein complex and κ-casein polymer is rod-like.
