PubMed Health⌕ Search

Biomedical subjects

D Fujimoto

Publications and source records attributed to D Fujimoto.

At least 73 records · Page 4Linked to original sources
PubMed1981

Electrochemical behaviour of pyridinoline, a crosslinking amino acid of collagen.

Pyridinoline is a crosslinking amino acid isolated from collagen. Polarographic oxidation and reduction potentials of pyridinoline were measured and compared with those of structurally related compounds, 3-hydroxypyridine, pyridoxine, pyridoxal, and N-methylpyridoxine. Oxidation and reduction potentials of these compounds were found to be near anodic and cathodic limit potentials, respectively, except for pyridoxal. This indicates that a 3-hydroxypyridine ring is very difficult to be reduced or oxidized. The reducibility of pyridinoline with a reducing agent, sodium borohydride, was also studied. It was not reduced by the reagent, however, it was found to be decomposed by light during the treatment. These results indicate that pyridinoline is a so-called "non-reducible" crosslink.

Amino Acids↗
PubMed1981

Synthesis of pyridinoline during in vitro aging of bone collagen.

Pyridinoline is a non-reducible crosslink of collagen. The changes in the content of this crosslink during in vitro aging of bone collagen were studied. The pyridinoline content of bone collagen of 6-week-old chick was very low. When the collagen was incubated with physiological saline in air at 37 degrees C, the pyridinoline content increased markedly. After 6 weeks, the content reached the same level as that of the adult. The synthesis of pyridinoline was inhibited when air was excluded. The in vitro aged collagen was less susceptible to pepsin than the untreated collagen. The results indicate that pyridinoline is one of the mature crosslinks of collagen and plays a role in the stabilization of collagen fibers.

Aging↗
PubMed1981

Increased histone acetylation and deacetylation in rat ascites hepatoma cells.

Rates of histone acetylation and deacetylation in nuclei from fetal, adult, and two kinds of neoplastic rat hepatocytes were examined. Histone acetylation in isolated nuclei was measured in the presence of 6 mM sodium n-butyrate, a potent inhibitor of deacetylase, and in the absence of the inhibitor. The deacetylase activity was estimated from the difference between the rates with or without the inhibitor. Both histone acetylation and deacetylation in nuclei from hepatoma cells (AH 66 cells) occurred two times faster than those of nuclei from fetal and adult livers regardless of alpha-fetoprotein production. This increased acetylation and deacetylation in hepatoma cells may be ascribed to either the increased activities of the enzymes or the increased accessibility of histone to the enzymes in the chromatin. Autoradiographic analysis of acetylated histones showed that all of the internal histones of the nucleosomes were acetylated and that apparent difference was found in the pattern of acetylated fractions between hepatoma nuclei and normal liver cell nuclei.

Acetylation↗
PubMed1979

Crosslink of collagen in hypertrophic scar.

It is conceivable that intramolecular and intermolecular crosslinks of collagen may be involved in the formation of hypertrophic scar, but little is known about the relationship between hypertrophic scar and crosslinks of collagen. We have isolated a new crosslinking amino acid from collagen and have named it pyridinoline. In this investigation, we examined the content of pyridinoline in human normal skin, mature scar and hypertrophic scar. An appreciable amount of pyridinoline was found in collagen of hypertrophic scar, but pyridinoline is virtually absent in collagen of normal skin.

Adolescent↗
PubMed1978

(Lysyl-Glycyl-Glycyl)5 and (Lysyl-Glycyl-Glycyl)10 as models of histone. Interaction with DNA and acetylation by calf thymus enzyme.

Sequential polypeptides (Lys-Gly-Gly)5 and (Lys-Gly-Gly)10 were synthesized as models for the N-terminal region of H4 histone and their interactions with DNA were studied. The ability of (Lys-Gly-Gly)10 to precipitate DNA was found to be much higher than that of (Lys-Gly-Gly)5. For example, at the physiological salt concentration, (Lys-Gly-Gly)10 precipitates DNA but (Lys-Gly-Gly)5 does not. Both peptides could be acetylated by a partially purified histone acetyltransferase preparation derived from calf thymus. epsilon-Amino groups of lysyl residues were the sites of the acetylation. DNA-cellulose chromatography of the products indicated that acetylation weakened the interaction of the peptides with DNA.

Acetylation↗
PubMed1978

Pyridinoline, a non-reducible crosslink of collagen. Quantitative determination, distribution, and isolation of a crosslinked peptide.

Pyridinoline is a crosslink compound isolated from bovine Achilles tendon collagen. It is a 3-hydroxypyridinium derivative with three amino and three carboxyl groups (Fujimoto, D., Akiba, K., & Nakamura, N. (1977) Biochem. Biophys. Res. Commun. 76, 1124-1129). The contents of pyridinoline in collagens from various sources were determined. The pyridinoline content of bovine Achilles tendon was 0.16 residue per 1,000 residues and that of rat Achilles tendon collagen was 0.017 residue per 1,000 residues. Besides Achilles tendon collagens, pyridinoline was found in collagens from costal cartilage, rib and femoral bone of rat. It was not found in collagens from the tail tendon and skin of rat. A crosslinked, triple-chained peptide containing pyridinoline was isolated from bovine Achilles tendon collagen after digestion with pronase. Its amino acid composition suggests that the peptide may be involved in an intermolecular crosslink among a carboxyterminal sequence, a sequence near the aminoterminus and a sequence in the helical region.

Amino Acid Sequence↗
PubMed1978

Age-related changes in the content of the collagen crosslink, pyridinoline.

Pyridinoline is a crosslinking amino acid of collagen fibers. The age-related changes in the content of pyridinoline were followed for collagens from human and rat costal cartilage and Achilles tendon. The pyridinoline content of the collagens in fetal or newborn animals was very low and increased markedly with growth of the animals. In rat tissues, the pyridinoline content continued to increase after the animal had reached maturity. On the other hand, in human tissues, it began to decrease after about 30 years of age. Pyridinoline may serve as an interesting index for the aging of connective tissues.

Aging↗
PubMed1978

Enzymic acetylation of nucleosome histone.

Rat liver chromatin prepared from purified nuclei catalyzed the acetylation of histones in nucleosomes at the same level as that of nuclei. The activity of histone acetyltransferase in chromatin was destroyed by heat treatment at 65 degrees C for 5 min. Histones in exogenously added nucleosomes also served as substrate for the enzyme. The sites of acetylation in the nucleosomes appeared to be in the trypsin-digestable N-terminal regions of histones H4, H3, and H2A, as has been reported in an in vivo system.

Acetyl Coenzyme A↗
PubMed1975

Action of bacterial collagenase on Ascaris cuticle collagen.

The collagen from the cuticle of Ascaris lumbricoides was digested by Clostridium histolyticum collagenase [EC 3.4.24.3] in the presence and absence of CaCl2. About 1.2 mumoles of amino groups per mg collagen was liberated when the digestion was performed in the presence of 5 mM CaCl2, whereas about 0.5 mumole of amino groups per mg collagen was liberated by digestion in the absence of CaCl2. In contrast, CaCl2 influenced the extent of hydrolysis of rat tail tendon collagen only slightly. The results suggest that CaCl2 is necessary for the hydrolysis of certain regions in the molecule of Ascaris collagen and that such structures may not be present in mammalian collagens.

Amino Acids↗