Solid-state conformations of oligopeptides possessing an -(Aib-ΔZPhe)2- segment

An X-ray crystallographic analysis was carried out for Boc-(Aib-ΔZPhe)2-Aib-OMe 1 and Boc-L-Pro-(Aib-ΔZPhe)2-Aib-OMe 2 (Aib = α-aminoisobutyric acid; ΔZPhe = α,β-dehydrophenylalanine; Boc = tert-butoxycarbonyl; OMe = methoxy) to provide detailed conformational data for oligopeptides possessing an -(Aib-ΔZPhe)2- segment. Both peptides adopted a typical 310-helical conformation characterized by = 52.8°, = 29.3°, and = -173.8° for the average values of the four residues of the -(Aib-ΔZPhe)2- segment in peptide 1, and = 54°, = 27°, and = -175° for those in peptide 2. The preference for a 310-helix in the -(Aib-ΔZPhe)2- segment is ascribed to the presence of Aib and ΔZPhe residues being strong inducers for the formation of a 310-helix. In peptide 2, the N-terminal L-Pro residue adopted a semiextended conformation, leading to a left-handed screw sense for the following achiral segment. This result was also supported by conformational energy calculation, in which the L-Pro residue leading to a left-handed 310-helical segment prefers a semiextended conformation rather than a right-handed helical conformation.journal articl

ニホン シャシン ビジュツ テンランカイ ニ オケル シャシン コウゲイ ブモン ノ ヘンセン ト ソノ イミ

学術論

Involvement of S-nitrosylation of actin in inhibition of neurotransmitter release by nitric oxide

<p>Abstract</p> <p>Background</p> <p>The role of the diffusible messenger nitric oxide (NO) in the regulation of pain transmission is still a debate of matter, pro-nociceptive and/or anti-nociceptive. <it>S</it>-Nitrosylation, the reversible post-translational modification of selective cysteine residues in proteins, has emerged as an important mechanism by which NO acts as a signaling molecule. The occurrence of <it>S</it>-nitrosylation in the spinal cord and its targets that may modulate pain transmission remain unclarified. The "biotin-switch" method and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were employed for identifying <it>S</it>-nitrosylated proteins.</p> <p>Results</p> <p>Here we show that actin was a major protein <it>S</it>-nitrosylated in the spinal cord by the NO donor, <it>S</it>-nitroso-<it>N</it>-acetyl-DL-penicillamine (SNAP). Interestingly, actin was <it>S</it>-nitrosylated, more in the S2 fraction than in the P2 fraction of the spinal homogenate. Treatment of PC12 cells with SNAP caused rapid <it>S</it>-nitrosylation of actin and inhibited dopamine release from the cells. Just like cytochalasin B, which depolymerizes actin, SNAP decreased the amount of filamentous actin cytoskeleton just beneath the membrane. The inhibition of dopamine release was not attenuated by inhibitors of soluble guanylyl cyclase and cGMP-dependent protein kinase.</p> <p>Conclusion</p> <p>The present study demonstrates that actin is a major <it>S</it>-nitrosylated protein in the spinal cord and suggests that NO directly regulates neurotransmitter release by <it>S</it>-nitrosylation in addition to the well-known phosphorylation by cGMP-dependent protein kinase.</p

ネパール ニ オケル トキソプラズマショウ ノ ケッセイ エキガク チョウサ

We studied the seroprevalence of anti-Toxoplasma antibodies among inhabitants of the Kathmandu Valley, Nepal (location of the capital, Kathmandu) and inhabitants of a village area in Lekhnath City, Kaski District (central Kathmandu), epal. A total of 376 serum samples were collected from apparently healthy participants. Toxoplasma antibodies (IgM and IgG) were detected by enzyme- linked fluorescent assay (ELFA). In the Kathmandu Valley, positive rates for Toxoplasma IgM and IgG antibodies were 1.4% (2/146) and 35.6% (52/146) respectively. In Lekhnath City, positive rates were 2.6% (6/230) for IgM antibodies and 60.4% for IgG antibodies, i.e., comparatively higher than those in the Kathmandu Valley. The higher prevalence of these antibodies in the Lekhnath City village area was associated with animal keeping in almost all households, while in the Kathmandu Valley only a few households kept animals. However, the seroprevalence of anti-Toxoplasma antibodies in these areas was relatively high in each case. Environmental conditions may be responsible for the transmission of Toxo- plasma parasites in both areas

ネパール ノ Kaski チク ニ オケル セイカツスイ ノ ビョウゲンセイ ビセイブツ オセン ジッタイ チョウサ

Diarrheal disease is one of the most important causes of morbidity and mortality particularly among children in the developing countries with poor water sanitation. In the rainy season of 2009, a study on enteropathogenic contamination was performed for the water supply in the Kaski District of Nepal. A total of 23 water samples, including 6 from Pokhara City (central city), 7 from Patneri Village (on the plain side), and 10 from Dhital Village (on the hill side) were investigated using a commercially available coliform bacilli kit, MPN Colilert (IDEXX Laboratories, USA). In total, 87% (20/23) water samples were positive for coliform bacilli (Escherichia coli) and 74% (17/23) for fecal coliform bacilli. All samples collected in Pokhara City and Dhital Village were positive for coliform bacilli while only 57% (4/7) of samples collected from Patneri Village were for coliform bacilli. With regard to fecal coliform bacilli, rates of positivity in these three locations were 100% (6/6), 80% (8/10), and 43% (3/7), respectively. Interestingly, water samples collected from schools at Dhital Village and Patneri Village showed both coliform bacilli and fecal coliform bacilli. These findings, particularly of fecal coliform contamination of water at schools, suggest the possibility of outbreaks of waterborne disease among children. We recommend effective sterilization of the water supply and improvement of knowledge of water safety in school children as well as people in general