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Biomedical subjects

T Imoto

Publications and source records attributed to T Imoto.

At least 199 records · Page 11Linked to original sources
PubMed1980

Taste relay neurons in the solitary tract nucleus of rats.

Impulse discharges of 82 solitary tract nucleus neurons, in response to natural stimulation of the oral cavity, were recorded. Among these, 52 units responded to taste stimuli and 30 units to mechanical stimuli. When the caudal end of the parabrachial nucleus was stimulated ipsilaterally, 16 taste and 5 mechanoreceptive units were excited antidromically. Response types of rostrally projecting taste neurons were not different from those of the non-projecting ones, and both of them were similar to that of the chorda tympani.

Afferent Pathways↗
PubMed1979

Lingual projections to the dorsal pons of the rat, studied by the field potential analysis.

Electrical stimulation of the chorda tympani (CT) of a rat produced a negative field potential with a peak latency of 8 msec localized in the parabrachial nucleus (PB) which may correspond to the pontine taste area. In contrast, stimulation of the glossopharyngeal nerve (GL) gave rise to no detectable negative field potential around the brachium conjunctivum. Stimulation of the lingual nerve (L) produced a large negative field potential with a similar latency, whose focus was found located just lateral to the focus of the negative potentials produced by CT stimulation.

Animals↗
PubMed1977

Molecular orientation in the stacked dimer form of 5"AMP in aqueous solution. A study by the NMR-desert method.

Molecular orientation of 5"-AMP in its stacked dimeric form in neutral aqueous solutions has been investigated at room temperature through the NMR-DESERT method proposed earlier by Akasaka et al. (J. Magn. Resonance, (1975) 18, 328-343). The effect of deuterium substitution of H8 of the adenine ring on the relaxation rate of H2 has become appreciable with increasing concentration of 5"-AMP, which should be attributed to the intermolecular H2-H8 interaction between adjacent adenine rings in the stacked dimer of 5"-AMP. The reciprocal sixth-power-averaged distance between H8 and H2 of the adjacent adenine rings in the stacked dimeric form obtained from the differential relaxation rate for H2 has been found to be almost constant (3.6 +/- 0.2 A S.D.) in the whole concentration range studied (0.1--1.0 M). The result has presented a direct proof of the existence of trans-stacking with a relatively large proportion (more than 60%) in the stacked dimeric form of 5"-AMP.

Adenosine Monophosphate↗
PubMed1976

A study of the native-denatured (N in equilibrium with D) transition in lysozyme. II. Kinetic analysis of protease digestion.

Kinetic analyses of the protease digestion of several chemical derivatives of lysozyme [EC 3.2.1.17] showed that only the D(denatured) state of the protein is digested and that the reaction velocity is proportional to the equilibrium constant (KD) of the N in equilibrium with D transition of the protein. Alteration of the net charge of lysozyme by acetylation caused a shift of the N in equilibrium with D transition to the right (ten-fold increase in KD compared to that of native enzyme). Both the formation of a lysozyme-inhibitor complex and the introduction of a covalent bond in the lysozyme molecule restricted the transition. The magnitude of the N in equilibrium with D transition is related to the susceptibility of lysozyme to protease digestion and it is estimated that the N in equilibrium with D transition in proteins is generally important in the intracellular catabolism of proteins.

Acetylation↗
PubMed1976

A study of the native-denatured (N in equilibrium with D) transition in lysozyme. III. Effect of alteration of net charge by acetylation.

Measurement of the enzymic activity and fluorescence properties showed that the gross conformation of acetylated lysozyme [EC 3.2.1.17] is very similar to that of the native enzyme. On the other hand, protease digestion, t-butyl hypochloride modification and thermal denaturation experiments performed on native, acetylated, and guanidinated lysozymes showed that acetylation caused a small but significant shift of the N in equilibrium with D transition to the right. Thus it can be concluded that charge balance in a protein plays an important role in maintaining its conformation. The difference between equilibrium and kinetic methods of monitoring protein denaturation was also clarified.

Acetylation↗
PubMed1975

Optical properties of lysozyme. pH and saccharide binding difference spectra.

Difference spectra associated with changes in pH and with binding of saccharides have been recorded for hen egg white (HEW) lysozyme, turkey egg white (TEW) lysozyme, and for the derivatives of the hen protein in which Tre-62 or Trp-108 had been oxidized specifically to oxindolealanine to give the Oxa-62 or Oxa-108-proteins. Identical pH difference spectra were obtained for HEW, TEW, and Oxa-62-lysozymes. Oxidation of Trp-108 is reflected in both the high and low pH (pH 7 versus 5 and pH 2 versus 5) difference spectra. The magnitude of the low pH difference spectrum is enhanced by binding of saccharide for HEW and Oxa-62-lysozymes but not for TEW lysozyme. The shapes and magnitudes of saccharide binding difference spectra are affected by oxidation of residues 62 or 108. These results can be interpreted in terms of the perturbations responsible for the lysozyme difference spectra. The pH 7 versus 5 difference spectrum results from perturbation by Glu-35 of Trp-108 and another tryptophan, probably Trp-63. Perturbation of Trp-108 and one or more other tryptophan residues by several carboxylate groups is responsible for the low pH difference spectra of the unliganded HEW and TEW lysozyme molecules. Perturbation of Trp-108 makes a principal contribution to the saccharide-binding difference spectrum. Perturbation of the Oxa-108 chromophore by ionization of Glu-35 or by saccharide binding produces absorbance changes in the 250 to 265 nm region.

Acetylglucosamine↗