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  • Glomerulocyte  (2)
  • KR-ET-1  (2)
  • Springer  (4)
  • 1995-1999  (4)
  • 1960-1964
  • 1935-1939
  • 1920-1924
Collection
Keywords
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  • Springer  (4)
Years
  • 1995-1999  (4)
  • 1960-1964
  • 1935-1939
  • 1920-1924
Year
  • 1
    Electronic Resource
    Electronic Resource
    Evidence for the role of the glomerulocyte in cellulose synthesis in the tunicate,Metandrocarpa uedai (1995)
    Springer
    Protoplasma 186 (1995), S. 24-33 
    Details
    ISSN: 1615-6102
    Keywords: Cellulose microfibril ; Electron diffraction ; Glomerulocyte ; Metandrocarpa uedai ; Tunic ; Vacuole-like structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The tunicate,Metandrocarpa uedai, contains a large quantity of cellulose; however, it is not known how and where the cellulose is synthesized. Based on evidence from electron diffraction and conventional thin-sectioning for electron microscopy, this study shows that the glomerulocyte is involved in the synthesis of cellulose. The bundles of microfibrils in the glomerulocyte as well as the tunic were identified as cellulose I using selected area electron diffraction analysis. The diffraction pattern of cellulose in the glomerulocyte was similar to that from the tunic, suggesting that the crystallization of cellulose already is initiated in the glomerulocyte. The diameter of cellulose microfibrils, both in the glomerulocyte and the tunic was the same, about 16 nm. These results suggest that the glomerulocyte is the most probable site for the synthesis of cellulose in the tunic ofM. uedai. Using thin-sectioning techniques, a series of observations showed that individual microfibrils are primarily assembled in structures tentatively identified as vacuole-like structures, then they are bundled by a tapering region within the vacuole-like structures. These bundles of microfibrils are deposited in a continuously circular arrangement. The microtubules are oriented parallel to the bundles of microfibrils at the tapering vacuole-like structure, and they may be involved in the tapering of these structures (perhaps controlling the shape). This study also provides the first account for the involvement of a vacuole-like structure in the synthesis of cellulose microfibrils among living organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276931
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  • 2
    Electronic Resource
    Electronic Resource
    High-resolution electron microscopy on ultrathin sections of cellulose microfibrils generated by glomerulocytes inPolyzoa vesiculiphora (1998)
    Springer
    Protoplasma 203 (1998), S. 84-90 
    Details
    ISSN: 1615-6102
    Keywords: Cellulose microfibril ; Cross-sectional shape ; Lattice image ; Lattice orientation ; Glomerulocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Glomerulocyte cellulosic bundles ofPolyzoa vesiculiphora were investigated by microdiffraction and high-resolution electron microscopy. In each bundle, hundreds of cellulose microfibrils, having a rectangular cross-sectional shape, are packed regularly with their 0.6 nm lattice planes parallel to each other. Lattice images reveal that the 0.6 nm plane is parallel to the longer edge of the cross section which is similar to the lattice organization of cellulose with a squarish cross section inValonia spp. More interestingly, all the microfibrils in a bundle have the same directionality of crystallographic c-axis, which suggests that the biosynthesis of the microfibrils within particular bundle occurs unidirectionally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280590
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  • 3
    Electronic Resource
    Electronic Resource
    Improvement in the oxidative folding of endothelin-1 by a Lys-Arg extension at the amino terminus: Implication of a salt bridge between Arg-1 and Asp8 (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 185-192 
    Details
    ISSN: 1573-3904
    Keywords: α-Helix ; Carboxamide substitution ; Circular dichroism ; Disulfide isomer ; KR-ET-1 ; Prosequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An amino-terminal extension of endothelin-1 by the Lys-Arg dipeptide in the prosequence (KR-ET-1) greatly increased the ratio of native-type to non-native-type disulfide isomer (96/4 versus 71/29) during the oxidative folding reaction. This improvement was completely abolished by substituting Asn for Asp at position 8 (D8N-KR-ET-1), whereas most of it was maintained with similar carboxamide analogues replaced at Glu10 or Asp18. Structure analyses by circular dichroism spectroscopy revealed that (i) in the carboxylate state, the α-helical content of the native-type isomer of KR-ET-1 is higher than that of the native-type isomer of ET-1, while such a variation is not observed in the corresponding non-native-type isomer of KR-ET-1; and (ii) the enhanced α-helicity resulting from the Lys-Arg extension is largely diminished in D8N-KR-ET-1. From these results and our previous findings that the helical structure in KR-ET-1 is stabilized by a particular salt bridge between the extended Arg-1 basic moiety and either the Asp8 or Glu10 acidic side chain in ET-1 [Aumelas, A. et al., Biochemistry, 34 (1995) 4546], we conclude that the formation of a specific salt bridge between the side chains of Arg-1 and Asp8 in KR-ET-1 is critical for the predominant generation of the native-type disulfide isomer, probably because it stabilizes the helical structure of parental ET-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008835323518
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  • 4
    Electronic Resource
    Electronic Resource
    Improvement in the oxidative folding of endothelin-1 by a lys-Arg extension at the amino terminus: Implication of a salt bridge between Arg−1 and Asp8 (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 185-192 
    Details
    ISSN: 1573-3904
    Keywords: α-Helix ; Carboxamide substitution ; Circular dichroism ; Disulfide isomer ; KR-ET-1 ; Prosequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An amino-terminal extension of endothelin-l by the lys-Arg dipeptide in the prosequence (KR-ET-1) greatly increased the ratio of native-type to non-native-type disulfide isomer (96/4 versus 71/29) during the oxidative folding reaction. This improvement was completely abolished by substituting Asn for Asp at position 8 (D8N-KR-ET-1), whereas most of it was maintained with similar carboxamide analogues replaced at Glu10 or Asp18. Structure analyses by circular dichroism spectroscopy revealed that (i) in the carboxylate state, the α-helical content of the native-type isomer of KR-ET-l is higher than that of the native-type isomer of ET-1, while such a variation is not observed in the corresponding non-native-type isomer of KR-ET-l; and (ii) the enhanced α-helicity resulting from the Lys-Arg extension is largely diminished in D8N-KR-ET-l. From these results and our previous findings that the helical structure in KR-ET-l is stabilized by a particular salt bridge between the extended Arg−1 basic moiety and either the Asp8 or Glu10 acidic side chain in Et-1 [Aumelas, A. et al., Biochemistry, 34 (1995) 4546], we conclude that the formation of a specific salt bridge between the side chains of Arg−1 and Asp8 in KR-ET-1 is critical for the predominant generation of the native-type disulfide isomer, probably because it stabilizes the helical structure of parental ET-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443532
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