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Hitoshi Suda

Publications and source records attributed to Hitoshi Suda.

10 recordsLinked to original sources
PubMed2006

Evidence for the existence of a soybean resistant protein that captures bile acid and stimulates its fecal excretion.

Feeding HMF, an insoluble "high-molecular-weight fraction" from an industrial enzymatic digest of a soy protein isolate, increased the fecal excretion of bile acid concomitant with increased fecal nitrogen. An amino acid analysis revealed that this increased fecal nitrogen could be explained by an increase in the insoluble protein fraction. This suggests the existence of an indigestible protein or peptide that can be called a "resistant protein" in the feces. The presumed resistant protein was rich in hydrophobic amino acids and bound bile acid by hydrophobic interaction. The residual fraction of HMF obtained after in vitro pepsin and pancreatin digestion, showed higher in vitro bile acid-binding capacity and excreted more bile acid in vivo than HMF. Its amino acid composition was similar to that of the feces of rat fed with HMF. These results suggest that the fecal resistant protein with bile acid-binding ability could be derived from the indigestible fraction of HMF.

Animals↗
PubMed2006

Age-related changes of mitochondrial structure and function in Caenorhabditis elegans.

A number of observations have been made to examine the role that mitochrondrial energetics and superoxide anion production play in the aging of wild-type Caenorhabditis elegans. Ultrastructural analyses reveal the presence of swollen mitochondria, presumably produced by fusion events. Two key mitochondrial functions - the activity of two electron transport chain complexes and oxygen consumption - decreased as animals aged. Carbonylated proteins, one byproduct of oxidative stress, accumulated in mitochondria much more than in the cytoplasm. This is consistent with the notion that mitochondria are the primary source of endogenous reactive oxygen species. However, the level of mitochondrially generated superoxide anion did not change significantly during aging, suggesting that the accumulation of oxidative damage is not due to excessive production of superoxide anion in geriatric animals. In concert, these data support the notion that the mitochondrial function is an important aging determinant in wild-type C. elegans.

Aging↗
PubMed2005

Direct measurement of oxygen consumption rate on the nematode Caenorhabditis elegans by using an optical technique.

It is well known that aging and longevity strongly correlate with energy metabolism. The nematode Caenorhabditis elegans is widely used as an ultimate model of experimental animals. Thus, we developed a novel tool, which is constructed from an optical detector, using an indirect method that can measure simply the energy metabolism of C. elegans. If we measure the oxygen consumption rate using this optical tool, we can easily evaluate the activity of mitochondria as an index in the aging process. However, a direct measurement of the oxygen consumption rate of C. elegans exposed in air is thought to be impossible because of the high concentration of atmospheric oxygen and the small size of the animals. We demonstrate here that we can directly detect the oxygen consumption with a small number of animals (<or=40) and a short accumulation time (<or=30 min) at high precision by using both an optical probe and a small chamber. The metabolic rate of a 4-day-old hermaphrodite animal, for example, was approximately 80 nW. Our method using C. elegans has the potential to become a useful technique for research on aging correlated with energy metabolism.

Aging↗
PubMed2004

2-Ureidoquinoline: a useful molecular element for stabilizing single cytosine and thymine bulges.

We have demonstrated that aromatic heterocycles having hydrogen-bonding surfaces complementary to those of nucleotide bases are effective molecular elements for the binding to single nucleotide bulges and base mismatches. We here report that a new molecule, 2-ureidoquinoline having an alignment of hydrogen-bonding groups in the order of acceptor-donor-donor stabilizes single cytosine and thymine bulges in duplex DNAs. Furthermore, a dimeric form of 2-ureidoquinoline stabilizes cytosine-cytosine and cytosine-thymine mismatches.

Base Pair Mismatch↗
PubMed2004

Force generation by recombinant myosin heads trapped between two functionalized surfaces.

Fluorescence resonance energy transfer measurements have revealed that the lever-arm domain of myosin swings when it hydrolyzes Mg-ATP. It is generally accepted that this swing of the lever arm of myosin is the molecular basis of force generation. On the other hand, the possibility that the force might be generated at the interface between actin and myosin cannot be ignored. However, there is a third possibility, namely, that myosin itself generates force without actin. Thus, using recombinant subfragment 1 molecules of Dictyostelium myosin II that were trapped between two functionalized surfaces of a surface-force apparatus, we determined whether myosin itself could actually generate force. Here, we report that, despite the absence of actin, myosin heads themselves have a capacity to generate a force (at least approximately 0.2 pN/molecule) that is coupled to the structural changes. Although the role of actin should not be neglected because muscle physiologically shortens as a result of the interaction between actin and myosin, in this work the focus is on the question of whether the catalytic domain of myosin has the capacity to generate force.

Adenosine Triphosphate↗
PubMed2004

The SPR sensor detecting cytosine[bond]cytosine mismatches.

We have synthesized the first surface plasmon resonance (SPR) sensor that detects cytosine-cytosine (C[bond]C) mismatches in duplex DNA by immobilizing aminonaphthyridine dimer on the gold surface. The ligand consisting of two 2-aminonaphthyridine chromophores and an alkyl linker connecting them strongly stabilized the C[bond]C mismatches regardless of the flanking sequences. The fully matched duplexes were not stabilized at all under the same conditions. The C[bond]T, C[bond]A, and T[bond]T mismatches were also stabilized with a reduced efficiency. SPR analyses of mismatch-containing 27-mer duplexes were performed with the sensor surface on which the aminonaphthyridine dimer was immobilized. The response for the C[bond]C mismatch in 5'-GCC-3'/3'-CCG-5' was about 83 times stronger than that obtained for the fully matched duplex. The sensor successfully detects the C[bond]C mismatch at the concentration of 10 nM. SPR responses are proportional to the concentration of the C[bond]C mismatch in a range up to 200 nM. Aminonaphthyridine dimer could bind strongly to the C[bond]C mismatches having 10 possible flanking sequences with association constants in the order of 10(6) M(-1). The facile protonation of 2-aminonaphthyridine chromophore at pH 7 producing the hydrogen-bonding surface complementary to that of cytosine was most likely due to the remarkably high selectivity of 1 to the C[bond]C mismatch.

Base Pair Mismatch↗
PubMed2004

Separation of mismatched DNA by using the affinity column immobilizing mismatch-binding ligands.

Mismatch binding ligands (MBL), ND and NA, bind to DNA containing mismatch base pairs. These MBLs were immobilized to NHS-activated affinity column via amine linker. Affinity chromatographic analyses of mismatched DNAs by using the ND-immobilized column showed clear separation of G-G and G-A from other mismatched DNAs. The results of the NA-immobilized column also showed good separation of A-A, G-A, G-G, A-C from other mismatched DNAs. The order of mobility of mismatched duplexes on MBL-immobilized column was in good agreement with that of the binding affinity in a solution phase obtained by the melting temperature measurement.

Base Pair Mismatch↗
PubMed2003

Detection of the C-C mismatched base pair by small ligands.

We synthesized 2-aminonaphthyridine derivatives that specifically bind to cytosine-cytosine (C-C) mismatch. The binding of ligands was verified by observing an increase of melting temperature for 11-mer duplexes containing a mismatch in the presence of ligands. It was found that the aminonaphthyridine dimer stabilized C-C mismatch more strongly than the monomer.

Base Pair Mismatch↗
PubMed2003

2,6-Diaminonaphthyridine derivatives bind to a single nucleotide bulge in DNA.

2,6-Diamino-1,8-naphthyridine derivative (daNpt), which possesses hydrogen bonding groups in an alignment of donor-acceptor-acceptor-donor binds to a single nucleotide bulge in the duplex. The melting temperatures (Tm) of all duplexes containing a bulge were increased, especially for the cytosine (C) and thymine (T) bulges, in the presence of daNpt, whereas only a small increase of Tm was observed for the fully matched duplexes. It was suggested by pH dependency of Tm and UV spectra, that a protonation of daNpt should play an important role for the recognition of C and T bulges.

Base Sequence↗