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  • 1995-1999  (3)
  • 1970-1974
  • EGFR  (1)
  • all parallel helix assemblies  (1)
  • enantiomeric conformations  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 123 (1997), S. 161-166 
    ISSN: 1432-1335
    Keywords: Key words Gestational trophoblastic disease ; EGFR ; Placenta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Gestational trophoblastic disease is an abnormal condition of the placenta, the incidence of which is very high in the State of Kerala, India. The biology of this disease is vague and methods to determine the malignant potential are limited. Placentae of normal (50) and molar pregnancies (95), including 32 showing persistent disease, were used for the study. Epidermal growth factor (EGFR), expression was evaluated by immunohistochemistry using monoclonal antibody, and quantified using the 125I-EGF-binding assay. EGFR was expressed more strongly in molar placentae than in normal placentae of similar gestational age, and was strong in the molar placentae of all gestational ages, whereas expression was mainly restricted to the first and second trimesters in normal placentae. Moles with early presenting symptoms (before 16 weeks) were at a higher risk of developing persistent disease. To conclude, the immunohistochemical study shows high expression of EGFR in early normal placentae and in moles, linking its role to the proliferative and differentiating activity of trophoblasts. Tumours with a histological diagnosis of invasive moles and choriocarcinoma showed very strong binding of EGFR. The present observations also suggest the possibility of mutated EGF receptors being present in persistent trophoblastic disease.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0006-3525
    Keywords: conformational interconversions ; peptide β-turns ; enantiomeric conformations ; chiral perturbations ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of the model tripeptide Boc-Aib-Gly-Leu-OMe (1) reveals two independent molecules in the asymmetric unit that adopt “enantiomeric” type I and type I′ β-turn conformations with the Aib and Gly residues occupying the corner (i + 1 and i + 2) positions. 13C cross polarization and magic angle sample spinning spectra in the solid state also support the coexistence of two conformational species. 13C-nmr in CDCl3 establishes the presence of a single species or rapid exchange between conformations. 400 MHz 1H-nmr provides evidence for conformational exchange involving a major and minor species, with β-turn conformations supported by the low solvent exposure of Leu(3) NH and the observation of NiH ↔ Ni+1H nuclear Overhauser effects. CD bands in the region 190-230 nm are positive, supporting a major population of type I′ β-turns. The isomeric peptide, Boc-Gly-Leu-Aib-OMe (2), adopts an “open” type II′ β-turn conformation in crystals. Solid state and solution nmr support population of a single conformational species. Chiral perturbation introduced outside the folded region of peptides may provide a means of modulating screw sense in achiral sequences. © 1998 John Wiley & Sons, Inc. Biopoly 45: 191-202, 1998
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 106-116 
    ISSN: 1075-2617
    Keywords: all parallel helix assemblies ; helix transition ; 310-/Α-HELICES ; two conformers ; water associated with non-polar helices ; X-ray crystallography ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The role of end groups in determining stereochemistry and packing in hydrophobic helical peptides has been investigated using an α-aminosobutyric acid (Aib) containing model nonapeptide sequence. In contrast to the Boc-analogue, Ac-(Aib-Val-Ala-Leu)2-Aib-OMe crystallizes with two independent molecules in a triclinic cell. The cell parameters are: space group P1, a=10.100(2)Å, b=15.194(4) Å, c=19.948(5) Å, α=63.12(2)°, β=88.03(2)°, γ=88.61(2)°, Z=2, R=7.96% for 5140 data where |Fo|〉3σ(F). The two independent molecules alternate in infinite columns formed by head-to-tail hydrogen bonding. The helices in the two independent molecules are quite similar to each other but one molecule is rotated ≍123° about its helix axis with respect to the other. All the helical columns pack parallel to each other in the crystal. Replacement of the bulky Boc group does not lead to any major changes in conformation. Packing characteristics are also similar to those observed for similar helical peptides.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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