We found that locations of arginine-specific gingipain (RGP) in the cellular fractions in the crude extract, envelope, vesicles, and culture supernatants were 48%, 16%, 17%, and 31%, respectively, and the corresponding values of lysine-specific gingipain (KGP) were 47%, 10%, 7%, and 36%, respectively. Although the molecular mass of RGP in the culture supernatant had been determined as 43 kDa, and that of KGP had been as 48 kDa, molecular masses of both proteinases solubilized from the vesicles were estimated to be over 1,500 kDa, since they eluted in the void volume of the column in the gel filtration on Sephacryl S-300. There was no reduction of molecular size by the following treatment with SDS, high-concentration NaCl, or urea. Interestingly, the occurrence of the macromolecular forms could not observed in other enzymes tested such as monopeptidyl, dipeptidyl, and tripeptidyl peptidases, as well as alkaline phosphatase. Therefore, occurrence of the macromolecular forms may be restricted to the proteinases. When the vesicle and culture supernatants containing free RGP and KGP were mixed and incubated, neither RGP nor KGP seemed to bind to vesicles. RGP bound to the vesicle was found to be more stable to heat treatment than the free form, suggesting that association of RGP with the vesicle caused heat stability of this enzyme.

Prevotella nigrescens, lacking siderophores was found to bind to the hemoproteins. The binding was observed also in the envelope which was prepared by sonication of the cell. The binding occurred in the pH-dependent manner; the binding was observed below neutral pHs of the incubation mixtures but only slightly observed in the neutral and alkaline pHs. Furthermore, hemoglobin bound to the envelope was dissociated at high pHs buffers. Maximum amounts of hemoglobin bound to 1 mg envelope was 51.2 μg. Kd for the reaction at pH 5.0 was 2.1 × 10-10M (210 pM). From the dot blot assay, hemoglobin could bind to a protein solubilized from the envelope by a detergent, referred to as hemoglobin-binding protein (HbBP), then it was purified by the sequential procedures of ion exchange chromatography, affinity chromatography and isoelectric focusing. Molecular weight and isoelectric point of the HbBP were 46 kDa and 6.1, respectively.

We examined the change of HSP70 expression in the mouse dental pulp which was exposed to experimental teeth separation by immunohistochemistry as a model for conservative dental treatment. Eight week-old 18 male ddY mice were used and a wedge was inserted between upper 1 st and 2 nd molars for 3 hours. In the experimental group, HSP70 expression increased in the dental pulp tissues. The expression was the greatest at 24 hours after which it gradually decreased to become similar to the level of the control group at 1 week. These results suggest that when immunohistochemical expression of HSP70 is used as an index, almost no severe damage occurs upon clinical application of a wedge insertion.