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'Enzyme' in keywords Facet   Publication Year 1979  [X]
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1979[X]
1Author    Ingrid Pilz, K. Arin Goral, FriedrichV D HaarRequires cookie*
 Title    Phenylalanyl-tRNA Synthetase from Baker'Yeast: Structural Organization of the Enzyme and Its Complex with tRNAPhe as Determined by X-Ray Small-Angle Scattering  
 Abstract    The quaternary structure of the phenylalanyl-tRNA synthetase and its complex with tRNAPhe was studied in dilute solutions by small angle X-ray scattering. For the free synthetase the radius of gyration was determ ined as 5.5 nm, the volume 523 nm 3, the maximum diam eter 17.5 nm and the m olecular weight as 260 000 using an isopotential specific volume of 0.735. The overall shape could be best approxim ated by a flat cylinder with dimensions 18.2 n m X l l .5 n m X 4 nm ; the loose structure was approxim ated by building up the cylinder by spheres (diam eter 4.2 n m). The corresponding param eters of the enzyme tRN A complex were the following: radius of gyration 5.9 nm, volume 543 nm 3, maximum diam eter 21 nm and m olecular weight 290 000. These param eters suggest an 1:1 complex, whereby it m ust be assumed that the tRN A m olecule is attached in the extension of the longer axis. From the difference in the distance distribution functions of the free enzyme and the complex it is evident that we have to assume a change of conform ation (contraction) of the enzyme upon the binding of the specific tRNA. 
  Reference    Z. Naturforsch. 34c, 20 (1979); received November 20 1978 
  Published    1979 
  Keywords    X-Ray, Small-Angle, Scattering, Enzyme, Complex 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0020.pdf 
 Identifier    ZNC-1979-34c-0020 
 Volume    34 
2Author    Yun-Fuk Tsang, RagaiK. IbrahimRequires cookie*
 Title    Evidence for the Existence of meta and para Directing O-Methyltransferases in Tobacco Cell Cultures  
 Abstract    The O-methyltransferase of tobacco cell culture was resolved to its meta and para directing forms by chromatography on DEAE-cellulose. Despite similarities in molecular weights and pi values of the two forms, however, evidence from pH optima, SH-group inhibitors, methylation ratios, SDS-acrylamide gels and mixed substrate experiments indicates the existence of two discrete enzymes acting at the meta and para positions of caffeic acid and quercetin, respectively; though the latter enzyme was less substrate specific than its meta counterpart. 
  Reference    Z. Naturforsch. 34c, 46 (1979); received November 17 1978 
  Published    1979 
  Keywords    O-Methyltransferase, Enzyme, meta and para Methylation, Phenols, Tobacco Cell Suspension Culture, Nicotiana tabcaum 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0046.pdf 
 Identifier    ZNC-1979-34c-0046 
 Volume    34