Effects Of Polyols On The Stability Of Cellulase Under Adverse Environment

This paper by measuring the residual activity of cellulase in adverse environment, investigated the polyols on the stability of cellulose, and used the kinetic of thermal inactivation, the deactivation of cellulase thermodynamics and the spectroscopy in discussing the action mechanism of cellulase under adverse environment.The results proved that polyol has protective effect on the activity of cellulose, different polyols have different protection effects on cellulose to the same condition, the same kinds of polyol has different protection effects to different conditions.The effects of freeze drying conditions, in order:sorbitol> mannitol> glycerol> trehalose.Freeze drying can cause α--helix and β--pleated sheet of cellulase increased and randomcoil reduced, this kind of change can be prevented by adding polyols.Under the condition of high temperature, in the protective effect of sorbitol> mannitol> glycerol> trehalose.thermal disposal led to the thermal inactivation rate constant of cellulase rised and half-life reduced, it can be changed by adding polyols. In the meantime, The parameters of cellulase thermodynamics△U*、△H*、△G*increased,△S*remain the same, it Show that there is no change in the chaos of system with adding polyols, △H*always represents of hydrogen bonding, so hydrogen bonding probably increased both inside and outside of cellulose molecule with adding sorbitol, mannitol, glycerin or inositol, its good for space structure of cellulose remain and thermostability of cellucase increasing.Fluorescence spectrum analysis Indicated that zymorotein got redshift after thermal disposal, Tryptophan and tyrosine inside turned nonpolar to polar environment, this was due to protein tertiary structure changed into disorder, polypeptidechain lost their structure and unfoldingExtreme pH polyols on enzyme activity, in the protective effect of protective effect for: glycerol> sorbitol>> inositol mannitol.UV scanning showed that acid destructed aromaticaminoacid, add a polyols prevented this kind of behavior. But alkali did not,the structure is speculated has not damaged, the reason of deactivation of cellulase is that actve center was attacked by hydrion.Polyols for freeze drying and high temperature protected cellulase activity through maintained the conformation of protein, this caused by energy in essence, for extreme pH environment, hydrion and hydroxylion is different from energy, the protection mechanism of cellulase is that polyols prevent hydrion or hydroxylion entered into and attacked activity center for extreme pH under the condition.