Tryptophanyl-tRNA synthtase de pancreas de buf : Caractristiques des chromophores intrinsques et extrinsques en relation avec le conformation de l'enzyme et de son site actif
Nicole Cittanova; Annette Alfsen
Febs Journal 13(3): 539-547
ISSN/ISBN: 1742-464X DOI: 10.1111/j.1432-1033.1970.tb00958.x
A simple and rapid method of obtaining, from beef pancreas, a homogeneous tryptophanyl-t Rna synthetase without tryptophan, is described. Spectrophotometric and fluorimetric methods have provided new insights into the conformation of the enzyme in absence of substrate. By spectrophotometry, 26 tyrosine groups per mole of enzyme are titrated in the native protein. These chromophores present an abnormally high p K of 11.3 and also have a low accessibility to ethylene glycol and glycerol.