Fast reaction techniques conformational changes

Previous investigations of helix-coil transition kinetics, which used a variety of fast relaxation methods (electric field jump, ultrasonic absorption, dielectric relaxation and temperature jump), encountered many difficulties (12). The systems studied were long homopolymers (>200 residues) that often had hydrolyzable side chains. Controversial results have been reported, depending on the experimental technique employed, because unwanted side chain reactions or molecular reorientation were often difficult to distinguish from the helix-coil conformational change. However, as observed here, a maximum in the relaxation times was detected for these experiments ranging from 15 ps to 20 ns and was attributed to the helix-coil transition. 

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