The Effect Of Amphiphiles On Structure And Function Of CBH1

Naturally, cellulose degradation is the restrictive step that determines the overall degradation of lignocellulose.To elucidate the relationship between the structure and function of cellulase is great significant to improve cellulose degradation efficiency. A surfactant has a polar head and a hydrophobic tail. Protein shows the characteristics of amphoteric electrolyte in different pH solutions. We will study the interaction between them.Trichoderma reesei can use cellulose, and the yield of CBH1reached60%of the exocytosis cellulose. CBH1has excellent potential application.I use two solutions:20mmol/L pH3.0citrate acid-Na2HPO4and50mmol/L pH5.0acetate buffers. In this experienment,0.5mg/mL CBH1in corresponding buffer was added into gradient concentration surfactants until the CBH1of enzymatic activity remained stable under a special concentration at30℃,. Then CBH1was treated by the same concentration surfactants for one hour (the chosen time). Circular dichromatism spectrum and fluorescent spectrum of CBH1were detected and Ultraviolet-visible spectrum of CBH1was applied within2h after surfactants’adding to immediately.Experimental results indicate that activity of CBH1is greatly related with its structural changes by surfactants. Remarkable deactivations appeared when anionic surfactant SDS affected with CBH1under pH3.0. There exists strong static electricity, enzymatic activity loss, secondary structures changes, intensity increases. After removing SDS by dialysis in pH5.0buffer, enzyme activity recovered a little. But after removing SDS in pH3.0buffer, enzyme activity can not recover. When SDS reacts with CBH1under pH5.0, there is no strong static electrictity, Enzyme activity drops slightly by SDS hydrophobic interaction. SOS with shorter hydrocarbon chain is anionic surface active agent. The results indicate that hydrophobic interaction of SOS is very weak, and the activity of CBH1changes slightly. The electrictity is the main interaction in pH3.0buffer. When SOS’s concentration is very high, the activity of CBH1decreases a little. But SOS does not destruct the activity of CBH1. The result of removing SOS is the same with that of SOS added. Contrarily, cationic surfactant CTAB has different effects. CBH1has a static charge in pH3.0buffer, and no effects on enzyme activity with adding CTAB. CBH1has a negative charge in pH5.0buffer. CTAB causes the superficial enzymatic activity decrease rather than total loss. There is no change with ultraviolet-visible spectrum scans. All above indicates that hydrophobic tails of CTAB penetrate into the inner structure of CBH1, hence leading to the decomposition of its tertiary and secondary strutures. Endogensis flurescent amino acids expose and locate in a new ionic environment. But the activity of CBH1can recover after removing CTAB by dialysis.