TEMPERATURE-JUMP-INDUCED REFOLDING OF RIBONUCLEASE-A - A TIME-RESOLVED FTIR SPECTROSCOPIC STUDY

FTIR difference spectroscopy has been used for the first time to inves tigate the kinetics of secondary structure formation during refolding, The refolding process of ribonuclease A (RNase A) as a model system w as induced by applying a temperature-jump of 60 degrees. The temperatu re-jump was triggered by rapidly injecting a small volume of the therm ally unfolded protein solution at 80 degrees C into a special cuvette system kept at 20 degrees C. The dead-time of the injection and the ti me resolution of the FTIR spectrometer permitted the observation of re folding processes in a time window ranging from 170 ms to several minu tes. Specifically, the formation of beta-structures and the disappeara nce of irregular conformations could be observed in this time interval .