Deuterium oxide stabilizes conformation of tubulin: A biophysical and biochemical study

Abstract

The present study was aimed to elucidate the mechanism of stabilization of tubulin by deuterium oxide (D2O). Rate of decrease of tryptophan fluorescence during aging of tubulin at 4 degrees C and 37 degrees C was significantly lower in D2O than in H2O. Circular dichroism spectra of tubulin after incubation at 4 degrees C, suggested that complete stabilization of the secondary structure in D2O during the first 24 hours of incubation. The number of available cysteine measured by DTNB reaction was decreased to a lesser extent in D2O than in H2O. During the increase in temperature of tubulin, the rate of decrease of fluorescence at 335 nm and change of CID value at 222 nm was lesser in D2O. Differential Scanning calorimetric experiments showed that the T-m values for tubulin unfolding in D2O were 58.6 degrees C and 62.17 degrees C, and in H2O those values were 55.4 degrees C and 59.35 degrees C.