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Biomedical subjects

Y Tanizawa

Publications and source records attributed to Y Tanizawa.

66 records · Page 4Linked to original sources
PubMed1987

Isolation and characterization of two types of cDNA for mitochondrial adenylate kinase and their expression in Escherichia coli.

Two cDNA clones for mitochondrial adenylate kinase were isolated from a cDNA library of bovine liver poly(A)+ RNA by using synthetic oligodeoxynucleotides as probes. The clone containing a 0.9-kilobase insert had the reading frame for a 241-residue protein (AK2A), while the other clone containing a 1.6-kilobase insert had the frame for a 234-residue protein (AK2B). Nucleotide sequences of these two clones were the same in the 5' portion up to the coding sequence for the 233rd residue, but different in the remaining 3' portions. The reported amino acid sequence of mitochondrial adenylate kinase from bovine heart corresponded to AK2A. Neither AK2A nor AK2B had a cleavable NH2-terminal presequence as that found in other imported mitochondrial proteins. RNA blot analysis of poly(A)+ RNAs from bovine liver and heart revealed three species of mRNA with approximate sizes of 0.9, 1.4, and 1.7 kilobases. The 1.7- and 1.4-kilobase species were specific for AK2B, whereas the 0.9-kilobase species was specific for AK2A. In the liver, the 1.7-kilobase mRNA was more abundant, whereas in the heart the 0.9-kilobase mRNA was predominant. The 1.4-kilobase mRNA was present only in the heart. The AK2A- and AK2B-coding sequences were expressed in Escherichia coli cells under the control of trc promoter. Both the products reverted the temperature-sensitive phenotype of the adenylate kinase mutant of E. coli.

Adenylate Kinase↗
PubMed1987

High level expression of chicken muscle adenylate kinase in Escherichia coli.

Chicken muscle adenylate kinase was produced in a large amount in Escherichia coli cells harboring an expression plasmid, pKK-cAKl-1. The plasmid was constructed by placing the cDNA sequence for chicken muscle adenylate kinase after the tac promoter. After induction by isopropyl-beta-D-thiogalactopyranoside, the enzyme protein amounted to about 10% of the bacterial proteins. The enzyme was readily purified in two steps by using phosphocellulose and Sephadex G-100 columns. The apparent molecular weight of the enzyme produced in E. coli was estimated to be 22,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, in agreement with the value deduced from the cDNA sequence. Ten amino acids in the NH2-terminal region were determined, and were identical with the sequence deduced from the cDNA sequence except that the terminal methionine was absent. Michaelis constants for ATP, ADP, and AMP of the enzyme thus synthesized were essentially identical to those determined with the enzyme in crude extracts of chicken skeletal muscle.

Adenylate Kinase↗
PubMed1986

Isolation and characterization of cDNA for chicken muscle adenylate kinase.

A cDNA clone for muscle adenylate kinase was isolated from a cDNA library of chick skeletal muscle poly(A)+ RNA, and the DNA sequence was determined. The cDNA insert had 854 nucleotides, which consisted of the 5'-untranslated sequence of 57 nucleotides, the sequence of 582 nucleotides coding for 194 amino acids, and the 3'-untranslated sequence of 163 nucleotides and the poly(A) tail of 52 nucleotides. The amino acid sequence predicted from the nucleotide sequence was highly homologous with the reported sequences of human, calf, porcine, and rabbit muscle adenylate kinases. RNA blot analysis of poly(A)+ RNA from various chicken tissues revealed a single species of mRNA of approximately 850 nucleotides and its tissue-specific distribution. The induction of muscle adenylate kinase mRNA synthesis during the chick embryogenesis was also demonstrated by the blot analysis. Southern blot analysis indicated a single gene for muscle adenylate kinase in the chicken genome.

Adenylate Kinase↗
PubMed1986

Circadian cycles in VIP content and VIP stimulation of cyclic AMP accumulation in the rat pineal gland.

VIP content in the rat pineal gland and cyclic AMP accumulation in response to VIP in the daily light and dark cycle were examined. VIP content in the pineal varied significantly during the day and night; the content decreased during exposure to light and was lowest at the onset of darkness, 6 p.m. (mean +/- SE, 23 +/- 5 pg/pineal), and increased during the night and was highest at the onset of light, 6 a.m. (72 +/- 12 pg/pineal). Response of cyclic AMP accumulation to VIP varied with a periodicity inversely related to the daily light and dark cycle of VIP content; cyclic AMP accumulation in response to 10(-7) M VIP increased in proportion to periods of exposure to light and peaked at 6 p.m., and decreased with the onset of darkness.

Animals↗
PubMedDate not supplied

Salivary films on hydroxyapatite studied by an in vitro system for investigating the effect of metal ions and by a quartz-crystal microbalance system for monitoring layer-by-layer film formation.

The salivary film or the acquired pellicle is a protein film formed initially on the enamel surface of teeth. Such a film plays an important role in enamel protection, but is also an initial substructure for the formation of plaque and the cosmetically undesirable colored stain. The composition and the structure of the film are still essentially unknown because of the difficulty of its isolation for characterization. The purpose of this study was to investigate the effect of some metal cations on the salivary film or the pellicle formation, and also to clarify the mechanism of development. First, using infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS), the in situ-formed film in the mouth was confirmed to contain selectively adsorbed well-known proteins. Then, in vitro studies have demonstrated that Ca2+ ions enhance film formation at the initial stage in virtue of Ca bridging and, interestingly, that Mg2+ ions oppositely inhibit the formation. Furthermore, the quartz-crystal microbalance (QCM), utilized successfully for the first time to study the salivary film, has shown the possibility of an alternate accumulation mechanism by which the surface charges on the film are effectively reversed by the opposite charged proteins.

Durapatite↗
PubMedDate not supplied

Reaction characteristics of a tooth-bleaching agent containing H2O2 and NaF: in vitro study of crystal structure change in treated hydroxyapatite and chemical states of incorporated fluorine.

This in vitro study was performed to elucidate the reaction mechanism of sodium fluoride (NaF), which is added to tooth-bleaching agents to lessen the adverse effect of hydrogen peroxide (H2O2) on teeth. Both hydroxyapatite (HAP) and dihydrated dicalcium phosphate (DCPD), model substances for dental hard tissues, dissolved easily in a simple H2O2 solution. In the H2O2/NaF solutions, however, fluorine compounds that could not be identified by X-ray diffraction (XRD) due to the smallness of the products were formed on the surface of the HAP. X-ray photoelectron spectroscopy (XPS) studies demonstrated that fluoridated hydroxyapatite (FHAP) was formed on HAP, and that calcium fluoride (CaF2) formation was accelerated by increasing the concentrations of fluorine and H2O2 along with the partial dissolution of HAP. In H2O2/NaF solution, DCPD also transformed easily to FHAP and CaF2, which are favorable to the remineralization process on the tooth surface. Thus, the mechanism of NaF was elucidated, and its use together with H2O2 for tooth bleaching was proved to be effective. Methodologically, the XPS two-dimensional plot made it possible for the first time to directly estimate the ratio of FHAP and CaF2 in the reaction products, in contrast to the conventional wet-analytical method, which is simply based on the difference in solubility of the two components.

Crystallization↗