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Biomedical subjects

Y Kuboki

Publications and source records attributed to Y Kuboki.

At least 109 records · Page 6Linked to original sources
PubMed1988

Occurrence of three distinct molecular species of chondroitin sulfate proteoglycan in the developing rat brain.

More than 60% of brain chondroitin sulfate proteoglycans were extracted from 10-day-old rat brains by homogenization in ice-cold phosphate-buffered saline containing protease inhibitors. Although the soluble proteoglycan preparation was a mixture of chondroitin sulfate proteoglycans with a different hydrodynamic size as well as a different molecular density, each subfraction of the proteoglycans contained chondroitin sulfate side chains with virtually identical molecular weight (approximately 15,000) and chondroitin sulfate disaccharide composition (high content of 4-sulfate unit). Digestion of the purified proteoglycan preparation with protease-free chondroitinase ABC produced five core proteins with Mr = 250,000 (designated as 250K protein), 220,000 (220K), 150,000 (150K), 130,000 (130K), and 93,000 (93K). All these core proteins were obtained from chondroitin sulfate proteoglycan preparations extracted from various regions of the brain, but their composition varied among different brain regions. Analysis for amino acid composition of these core proteins and two-dimensional mapping of their proteolytic peptides revealed that three major core proteins (250K, 220K, and 150K proteins) were structurally different. These observations indicate that at least three distinct types of chondroitin sulfate proteoglycan occur in the developing rat brain.

Amino Acids↗
PubMed1988

Time-dependent changes of collagen crosslinks in the socket after tooth extraction in rabbits.

Time-dependent changes of the reducible collagen crosslinks in the healing tissue of rabbit tooth extraction wounds were analyzed chromatographically. The ratio of dihydroxylysinonorleucine to hydroxylysinonorleucine in the collagen from normal alveolar bone was 4.4. This value increased about four times, on the 10th day after tooth extraction, coinciding with the phase of active woven bone formation, and then decreased rapidly toward a normal value on the 14th day after tooth extraction. The data suggest that active biosynthesis and fibrillogenesis of bone collagen precede the morphological completion of lamellar bone formation.

Alveolar Process↗
PubMed1988

Increase of dentin phosphophoryn with dentin formation.

Dentin phosphophoryn was quantified on bovine and rabbit dentin at three developmental stages. Phosphophoryn was extracted from teeth with 0.6M HCl, and quantified as optical density on DEAE-cellulose chromatogram or as phosphoserine content. Bovine phosphophoryn showed progressive increase with formation of dentin. Matrix-associated phosphophoryn was also quantified as phosphoserine content in insoluble dentin residue which was extracted with 6 M urea after decalcification. This fraction increased with formation of dentin both in bovine and rabbit dentin. Phosphophoryn is thought to be related to the later stage of dentin formation.

Animals↗
PubMed1987

High production of type VI collagen in multiple fibromatosis with multiple articular dysplasia.

A patient with multiple fibromatosis occurring at the sites of multiple cartilagenous dysplasia was described. Collagen types solubilized with pepsin from the fibromatous tissue were fractionated by a different salt concentration and analyzed by SDS-polyacrylamide gel electrophoresis, which indicated that the tissue produces predominantly "short-chain" collagen. Western blotting of the subunits indicated a cross reaction with antisera of the type VI collagen. The results of rotatory shadowing electron microscopy confirmed the characteristic short-chain structure.

Amino Acids↗
PubMed1987

Effects of dentin phosphophoryn on precipitation of calcium phosphate in gel in vitro.

In vitro precipitation of calcium phosphate was carried out using a one-dimensional double diffusion system in agar gel. Bovine dentin phosphophoryn enhanced the sharpness of the precipitation bands, although it reduced the total amount of the precipitates. Dephosphorylated phosphophoryn had no effect on the pattern of precipitates. Therefore, phosphophoryn is thought to raise the local density of nucleation in spite of its inhibitory activity on apatite formation.

Animals↗
PubMed1987

X-ray photoelectron spectroscopic studies of the adsorption of salivary constituents on enamel.

Time-dependent change of adsorption of salivary components on the outermost surface layer of enamel was studied by x-ray photoelectron spectroscopy. Adsorption of proteinaceous components, as monitored in terms of the relative mass of nitrogen, was detected within 30 min, increased with time, and reached a plateau at 90 min. Thus, the ratio of nitrogen to calcium in the two-hour sample increased to about 240 times that in the control sample. The ratio of carbon to nitrogen on the surface decreased to about one-half of that in the control sample. The data established the time required for equilibrium between the proteinaceous component in saliva and the amount of material adsorbed onto the tooth surface.

Adsorption↗
PubMed1986

New pepsin-solubilized low molecular weight collagenous component possibly unique to periodontal ligament.

Limited pepsin digestion of bovine periodontal ligament releases genetic types I, III, and V collagen and a high cystine containing low molecular weight collagenous component. Salt fractionation and molecular sieve chromatography allowed the isolation of the latter as an apparently pure homogeneous moiety which had an approximate molecular mass of 30 000 daltons. Reduction with mercaptoethanol yielded a single 10 000-dalton band on polyacrylamide gel electrophoresis in sodium dodecyl sulfate. This led us to conclude that the newly isolated low molecular weight collagen fragment consists of three similar molecular weight chains. Unreduced collagen-like glycoprotein (CGP) [Jander, R., Troyer, D., & Rauterberg, J. (1984) Biochemistry 23, 3675-3681] after extraction from tissues with collagen denaturing solvents yields the GP140 glycoprotein upon reduction and does not release any collagen fragment below 90 000 daltons upon mild or vigorous pepsin digestion. The GP140 glycoprotein [Heller-Harrison, R. A., & Carter, W. G. (1984) J. Biol. Chem. 259, 6858-6864] isolated by extraction under reducing and collagen denaturing solvent conditions did not yield a collagen fragment below 40 000 daltons after pepsin treatment. It was clearly shown that both CGP and GP140 yield type VI collagen fragments in the above-cited reports. Since this report demonstrates that the Mr 30 000 collagen fragment is only released by pepsin treatment of nondenaturing solvent treated periodontal ligament and that only very small peptides are found in denaturing solvent treated tissue after pepsin digestion, it is concluded that the newly isolated Mr 30 000 collagen fragment reported here is not derived from type VI collagen.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1986

Further study of hydroxyapatite high-performance liquid chromatography using both proteins and nucleic acids, and a new technique to increase chromatographic efficiency.

Previously developed hydroxyapatite high-performance liquid chromatography columns were tested further by using not only proteins but also nucleic acids. In both cases it was confirmed that the column can, in fact, discriminate subtle structural differences among molecules. Especially for protein mixtures a new technique was introduced to increase the efficiency of chromatography.

Animals↗
PubMed1986

Changes in interaction of bovine dentin phosphophoryn with calcium and hydroxyapatite by chemical modifications.

Dentin phosphophoryn was found to lose its precipitability with calcium ion when dephosphorylated or carboxylate-blocked, whereas precipitation of the intact protein was induced at calcium concentration as low as 2 mM. On the other hand, the adsorption capacity of phosphophoryn onto the hydroxyapatite surface increased when acidic groups were diminished by the above modifications.

Adsorption↗
PubMed1985

In vivo cleavage of dentin phosphophoryn following beta elimination of its phosphoserine residues.

Phosphophoryn, a unique phosphoprotein in dentin, has a polydisperse character. Keto acid was found to be present in this protein by condensation reaction with dinitrophenyl (DNP)-hydrazine and was identified to be pyruvate from the result that [3H]lactate was formed by the reduction of phosphophoryn with [3H]NaBH4. In the case of phosvitin, incorporation of DNP-hydrazine was much less than in phosphophoryn, even after the same treatment as the extraction procedure of phosphophoryn. DNP-hydrazine incorporation was much higher in the phosphophoryn of mature dentin than in dentin of unerupted teeth. From these results, pyruvate was though to be formed time dependently in vivo by beta elimination of phosphoserine residues and subsequent cleavage of the peptide chain, which may contribute to the polydispersity of phosphophoryn.

Animals↗
PubMed1984

Presence of lysinoalanine and histidinoalanine in bovine dentin phosphoprotein.

Trypsin digestion and successive calcium-induced precipitation of the insoluble bovine dentin matrix effectively separated the collagen and phosphoprotein fractions which were firmly associated together in this material. Amino acid analysis by four different systems revealed that the lysinoalanine and histidinoalanine, which had been previously reported to occur in the human dentin collagen, were concentrated in the phosphoprotein fraction but were not present in the collagen fraction. Furthermore, it was found that the free-type phosphoprotein which was isolated from EDTA extract of dentin powder also contained both "cross-linking" amino acids. The results indicated the both "cross-links" distributed within the dentin phosphoprotein and were not likely to contribute the unique stability of dentin collagen.

Animals↗
PubMed1984

Systematic purification of free and matrix-bound phosphophoryns of bovine dentin: presence of matrix-bound phosphophoryn as a distinct molecular entity.

Free and matrix-bound phosphophoryns, both highly phosphorylated proteins in dentin, were prepared from EDTA extract and CNBr-digests of bovine dentin. The two components were purified by DEAE-cellulose, SP-Sephadex, and gel filtration chromatography. The matrix-bound component was eluted as a distinct peak from the free component in the above chromatographic systems. Amino acid composition of the purified matrix-bound component indicated that this component consisted of phosphophoryn and collagen in the ratio of 2:3 based on the number of the residues. The matrix-bound component could not be reconstituted by mixing phosphophoryn with collagen CNBr peptides. Artificial crosslink products of free phosphophoryn and collagen CNBr-peptides by the carbodiimide method showed similar properties to the physiological matrix-bound phosphophoryn. The bond between phosphophoryn and collagen of the matrix-bound component is assumed to be a covalent crosslink.

Amino Acids↗
PubMed1983

Mechanism of differential staining in carious dentin.

The caries detector, 1.0% acid red solution in propylene glycol, failed to stain EDTA-demineralized bovine dentin matrix, but stained the same matrix when treated by lactic acid in a concentration above 0.01 M. Thus, acid of bacterial origin could possibly be responsible for the stainability change of carious dentin in vivo.

Animals↗
PubMed1982

Comparative molecular distribution of cross-link in bone and dentin collagen. Structure-function relationships.

Bone and dentin contain exclusively genetic Type I collagen. These collagens have identical amino acid sequences, cross-link precursors and cross-links yet serve different physiological functions. Complete tryptic digests of the intractable [3H]NaBH4-reduced demineralization collagen from bovine cortical bone and dentin have successfully been obtained. Chromatography of the tryptic peptides on Sephadex G-50 allowed separation of cross-link peptide fractions containing dihydroxylysinonorleucine. Chromatography of peptides of the same molecular weight distribution from each sample, which should contain identical peptides, yielded different chromatographic patterns on phosphocellulose. The phosphocellulose fractions containing the most abundant amounts of dihydroxylysinonorleucine were rechromatographed on DEAE-cellulose and yielded dissimilar profiles. It was concluded that the cross-link, dihydroxylysinonorleucine, has a different molecular distribution in bone and dentin collagen. The results demonstrate that the collagen derived from two different mineralized tissues, possess different micromolecular structures. These structural differences may be related to diverse physiological functions.

Animals↗