The adsorption of human submandibular-sublingual salivary proteins by synthesized and commercial hydroxyapatite (author's transl)

Abstract

A hydroxyapatite (HA) with the crystallinity similar to enamel powder of teeth, determined by analyses of X-ray diffraction, was chemically synthesized. Commercial HA (Lot. 30307, Seikagaku-kogyo Co., Tokyo) was lower in the crystallinity (determined by X-ray diffraction) than that of enamel powder and higher than that of dentin powder. It was studied on the adsorption of submandibular-sublingual (SM-SL) salivary proteins by these two types of HA, synthesized HA (S-HA) and commercial HA (C-HA). Fifteen ml of SM-SL saliva was added to 3.4g of S-HA and C-HA, respectively. Eighty-seven percent of salivary proteins added was adsorbed by C-HA, whereas only 58% of those added was adsorbed by S-HA. There were three salivary proteins which adsorbed on to C-HA but not on to S-HA. These subunit molecular weight were estimated by poly a crylamide gel electrophoresis in sodium dodecyl sulfate (SDS) and β-mercaptoethanol to be approximately 70, 000, 60, 000, and 56, 000. These proteins could be eluted from C-HA by a low concentration of phosphate buffer. Two proteins with estimated subunit molecular weight of approximately 120, 000 and 30, 000 were tightly adsorbed by both HA specimens. A salivary glycoprotein with high molecular weight also adsorbed on to both HA specimens. SDS-polyacrylamide gel electrophoresis in the absence and in the presence of β-mercaptoethanol indicated that the glycoprotein is composed of subunits linked by disulfide bridges.