Hydrogen-deuterium exchange random coil structure

Physico-chemical properties. In the fifties and sixties, several studies on the conformation of ACTH in solution were carried out. Among the used techniques were ORD, CD, fluorescence depolarization studies and kinetics of deuterium hydrogen exchange (for a review see ref. 2). The results pointed to a highly flexible random coil in solution however, Eisinger (40) found that the distance between Tyr and Trp [in ACTH-(1-24)] as measured by excitation spectroscopy, was in better agreement with some form of loop or helical structure. In addition. Squire and Bewley noted 11-15% helical content, located in the N-terminal 1-11 part of the molecule, when measuring the ORD of ACTH at pH 8.1 (41) (a random coil was found at neutral and acidic pH values, 2). 

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