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Biomedical subjects

H Watari

Publications and source records attributed to H Watari.

At least 127 records · Page 7Linked to original sources
PubMed1983

In vivo 31P NMR studies on experimental cerebral infarction.

Sequential metabolic changes in rat brain were monitored by in vivo measurements of 31P NMR spectra using a topical magnetic resonance (TMR) spectrometer, during the course of experimentally induced cerebral infarction and also during recovery produced by restoration of circulation. The experimental cerebral infarction was rendered by a slightly modified version of the method of Pulsinelli and Brierley (1979). The bilateral coagulation of the vertebral arteries at the level of alar foramina of the first cervical vertebra (preinfarction) did not show any change in NMR spectrum, but the subsequent bilateral ligation of internal carotid arteries produced a decrease in the peaks of ATP and phosphocreatine and a concomitant increase in the peak of inorganic phosphate within a few minutes. Intracellular pH, calculated from the chemical shift of inorganic phosphate, declined. These changes became maximal at approximately 30 min after the infarction. Reinstatement of blood flow to the cerebrum, produced by untying the ligature of internal carotid arteries, resulted in an immediate restoration of the peaks of ATP and phosphocreatine, which was followed by a reduction in the peak of inorganic phosphate within a few minutes. The spectrum recovered to its preinfarction pattern about 30 min after the restoration of the circulation. These experiments demonstrate that phosphorus compounds change very rapidly during infarction, and that these changes were reversible at least during a 30 min period.

Adenosine Triphosphate↗
PubMed1982

A resonance Raman study on the reaction intermediates of D-amino acid oxidase.

Resonance Raman (RR) spectra of two reaction intermediates of D-amino acid oxidase with substrate analogs were obtained. The reaction intermediates studied were (1) the one in the aerobic oxidative reaction of the enzyme with beta-cyano-D-alanine and (2) the other in the reverse reductive reaction of the enzyme with chloropyruvate and ammonium. Both intermediates are characterized with the charge transfer absorption bands in the long wavelength region extending beyond 600 nm. The RR spectra of the two intermediates excited at 488.0 or 514.5 nm are those of oxidized flavin, which is consistent with our previous assumption that oxidized flavin is involved in these reaction intermediates. Relatively simple RR spectra were obtained for these intermediates with excitation at 632.8 nm which is within the region of the charge transfer bands. The resonance enhancement for the Raman lines around 1585 and 1350 cm-1 for either of the intermediates with excitation in the region of the charge transfer bands suggests that the charge transfer interaction involves the N(5)-C(4a) region extending to the C(10a)-N(1)-C(2) region of the isoalloxazine nucleus. The Raman line at 1657 cm-1 for the intermediate with chloropyruvate and ammonium was assigned to C = N of an imino acid from the isotopic frequency shift upon 15N-substitution. The assignment substantiates our previous conclusion that the intermediate involves an imino acid, alpha-imino-beta-chloropropionate.

Aerobiosis↗
PubMed1982

Thermodynamic characterization of hog kidney D-amino acid oxidase apoenzyme in concentrated guanidine hydrochloride solution. Preferential interaction with the solvent components and the molecular weight of the monomeric unit.

This paper describes the physical characterization of the monomeric unit of hog kidney D-amino acid oxidase apoenzyme in 6 M guanidine hydrochloride (GuHCl) solution by means of differential refractometry, densimetry, light scattering, equilibrium sedimentation, and high-speed gel filtration chromatography. In 6 M GuHCl solution, the oxidase interacts preferentially with GuHCl: the values of the preferential interaction parameter are 0.11 +/- 0.03 (S.D.) g/g of protein by densimetry and 0.14 +/- 0.04 g/g of protein by refractometry. The volume change, delta V, of the oxidase on transfer from the native to the denatured state is -350 ml/mol. The molecular weight of the monomeric apoenzyme is 39,600 +/- 1,700 by light scattering and 38,000 +/- 1,200 by high-speed equilibrium sedimentation. The values of the molecular weight estimated by the empirical methods, i.e., sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and high-speed gel filtration chromatography in 6 M GuHCl, agree well with those obtained by the thermodynamic methods mentioned above. These results confirm definitely that the complex of the apoenzyme with SDS normally behaves in the same manner as those of standard proteins in SDS-gel electrophoresis. This is also supported in this study by the analysis of the electrophoretic data at several gel concentrations by Ferguson plots. The molecular weight of quasi-D-amino acid oxidase apoenzyme was also examined by the empirical methods.

Animals↗
PubMed1982

A study of the deformability of red blood cells of a teleost fish, the yellowtail (Seriola quinqueradiata), and a comparison with human erythrocytes.

The blood of a carangid fish, the yellowtail (Seriola quinqueradiata) has been studied with particular reference to the deformability properties of the red blood cells. The rate at which blood flows through a Nuclepore filter containing 5 micrometers pores has been determined under the same conditions that have been used with human blood. Marked differences were found in the flow of yellowtail blood which depended on the particular way in which the blood had been sampled. Such differences seem to be due to a sensitivity of fish red blood cells to their environmental conditions. Blood flow through filters is temperature-dependent, the rate increasing with a rise in temperature. Measurements made at 37 degrees C gave values which were similar to those normally obtained for human red blood cells, in spite of their greater dimensions (10.4 x 6.8 x 3.4 micrometers), and nucleated nature. It was also found that the blood flow rate of human blood was slower than that of yellowtail blood when measured at the normal environmental temperatures (15 degrees C) for these fish.

Animals↗
PubMed1981

Resonance Raman study of D-amino acid oxidase-inhibitor complexes.

The resonance Raman (RR) spectra of the complexes of D-amino acid oxidase (DAO) with benzoate derivatives were measured. The RR spectra of complexes of DAO with benzoate derivatives excited at 514.5 nm are similar to one another and also similar to that of oxidized flavin. In the cases of DAO-o-NH2-benzoate and DAO-o-OH-benzoate complexes, however, the line at 568 or 565 cm-1, derived from the benzoate derivative, was intensified. In the case of DAO-o-NH2-benzoate complex, which has an intense charge-transfer absorption band, the resonance enhancement of the Raman lines at 1583 and 568 cm-1 in the RR spectrum excited at 632.8 nm is striking. The former line is known to involve the vibrational displacements of the N(5) and C(4a) atoms of isoalloxazine and the latter is considered to be derived from a ring deformation mode of o-NH2-benzoate. This suggests that the o-NH2-benzoate molecule lies along the N(5)-C(4a) bond and parallel to the flavin face. A Raman line derived from o-OH-benzoate in the RR spectrum of DAO-o-OH-benzoate complex excited at 514.5 nm was detected. This result supports the view that the complex has a charge-transfer band, as has been pointed out by Massey and Ganther. Also, the spectrum of quasi-DAO-o-OH-benzoate complex is identical with that of the complex of DAO, suggesting that the active sites of these two enzymes have similar structures.

Aminobenzoates↗
PubMed1980

A study of the absorption, circular dichroism and magnetic circular dichroism spectra of a flavin derivative. The pi-electronic structure of 8-amino-8-demethyl-D-riboflavin.

The absorption, CD and MCD spectra of 8-amino-8-demethyl-D-riboflavin, which showed novel spectral properties, were measured in the spectral region from 220 nm to 540 nm and the spectra obtained were analyzed in terms of Gaussian wave number curves (from band I to band X). Semi-empirical calculations of the Pariser-Parr-Pople Hamiltonian were performed to investigate the novel spectral properties and the reactivity at the 5-position. The theoretical results as well as the experimental results showed that the novel spectral properties were a result of amino substitution at the 8-position.

Chemical Phenomena↗
PubMed1980

31P nuclear magnetic resonance study on perfused brain slices of guinea pig.

31P-NMR measurements of brain slices of guinea pig were successfully carried out for the first time with a new perfusion and spinning technique. The 31P-NMR spectrum showed resonance lines of phosphocreatine, fructose-6-phosphate, ATP, and inorganic phosphate. In the time course of the 31P-NMR spectra, the concentrations of phosphocreatine and fructose-6-phosphate, which were estimated from the initial spectrum, were 4.3 and 1.1 mumol/g of fresh tissue, respectively, and the estimates from the following ones showed that the concentration of phosphocreatine decreased to 2.7 mumol/g of fresh tissue while that of fructose-6-phosphate did not change significantly throughout the measurements.

Adenosine Triphosphate↗
PubMed1980

Studies on the reaction of D-amino acid oxidase with beta-cyano-D-alanine. Observation of an intermediary stable charge transfer complex.

The reaction of D-amino acid oxidase [EC 1.4.3.3] (DAO) from porcine kidney with beta-cyano-D-alanine (D-BCNA) was studied. DAO was found to catalyze elimination of the cyano group as well as oxidation of D-BCNA. During the course of the reaction in the presence of excess oxygen, an intermediate was observed which exhibited a characteristic absorption spectrum with a broad charge transfer band in the longer wavelength region. The CD spectrum of this intermediate resembles that of DAO-anthranilate complex. The rate of oxygen consumption in the aerobic reaction decreased with time, suggesting product inhibition due to complex formation between the enzyme and the product. Anaerobic addition of D-BCNA reduced the enzyme to its fully reduced state, the CD spectrum of which closely resembles that of the enzyme reduced by excess D-alanine. When an appropriate amount of D-BCNA was added to the enzyme under air, the charge transfer complex was observed immediately, and underwent a change to the reduced state as the oxygen was consumed. The binding strength in the charge transfer complex was found to be comparable to that in DAO-benzoate complex. The accumulating product in the oxidation of D-BCNA had a strong absorption at 285 nm. The aerobic reaction of beta-cyano-L-alanine (L-BCNA) with snake venom L-amino acid oxidase (LAO) produced the same product with an absorption at 285 nm as the reaction of DAO with D-BCNA. The product obtained in the reaction with LAO was found to form the same charge transfer complex with DAO. We tentatively identified this product as alpha-amino-beta-cyanoacrylate and the charge transfer complex as the complex of alpha-amino-alpha-cyanoacrylate with the oxidized enzyme. A hypothetical reaction pathway based on the present finding is proposed. Addition of L-BCNA to the enzyme produced an absorption spectrum very similar to that of the DAO-benzoate complex without oxidation or elimination. L-BCNA was found to be a competitive inhibitor of the oxidation of D-alanine.

Alanine↗
PubMed1980

Vibrational modes of flavin bound to riboflavin binding protein from egg white. Resonance Raman spectra of lumiflavin and 8-substituted riboflavin.

The resonance Raman (RR) spectra of 8-halogenated-riboflavin, 8-demethyl-riboflavin(8-H-RF), 8-amino-riboflavin(8-NH2-RF), 8-methoxy-riboflavin(8-OCH3-RF), lumiflavin, and 3-methyl-lumiflavin were observed. The Raman lines with the highest frequency are at 1624, 1620, and 1615 cm-1 for 8-chloro-riboflavin, 8-bromo-riboflavin, and 8-iodo-riboflavin, respectively. This systematic shift confirms that the 1631 cm-1 line of riboflavin is derived from the benzene part of isoalloxazine. Substitution at the 8-position by an amino or methoxy group, which has a large influence on the electronic structure of isoalloxazine, changes the RR spectrum markedly in comparison with that of 8-halogenated riboflavin. The 1583 cm-1 line of riboflavin, which involves the vibrational displacement of N(5) and C(4a) atoms of isoalloxazine, is shifted to the low frequency side by substitution at the 8-position with an amino or methoxy group. The corresponding line of 8-H-RF, on the contrary, shifts to the high frequency side. The RR spectrum of lumiflavin is very different from that of riboflavin in the range from 1200 to 1300 cm-1. Although the pi-electronic structure is little affected by the substitution at the 10-position, the Raman spectrum of lumiflavin in this region is very sensitive.

Binding Sites↗