Effect of plasma on composition of human enamel and cementum pellicle

Slabs of human enamel and cementum were incubated with plasma alone or with various mixtures of plasma and saliva. Proteins and glycoproteins that adsorbed to the surface of the slabs in 0 to 60 min were labeled by lactoperoxidase-catalyzed 125I-iodination and by mild periodate oxidation followed by NaB3H4 reduction. The labeled components were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and visualized by autoradiography or fluorography. From plasma alone, a 58 and a 66 kDa protein (probably albumin) were adsorbed to the enamel surface in relatively equal amounts, but no 125I-labeled components were detected on the cementum surface in the absence of saliva. Adding 10% saliva to the incubation mixture promoted the adsorption of the 58 and 66 kDa components to cementum. In addition, another set of proteins, including components of 44, 47, 29, and 25 kDa, was adsorbed to both cementum and enamel in the presence of saliva. These six proteins were the major 125I-labeled species in all of the pellicles formed from mixtures of plasma and saliva. The electrophoretic mobility of the major 120 and 140 kDa 3H-labeled sialoglycoproteins adsorbed to both cementum and enamel was similar to that of the low-molecular-weight mucin of submandibular/sublingual saliva.